JP2003305838A - Image recorder and method of recording image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress lowering of image quality due to color variation created by difference in orders of ejection of ink which is caused by performing high speed recording of an image by moving a recording head in both ways of inward and outward journeys in a scanning direction, the recording head having nozzles for different colors arranged in the scanning direction. <P>SOLUTION: When an image in a predetermined region in the scanning direction is recorded according to image data, an amount of each ink necessary for recording the image is counted, and then a gradation of achromatic color in the predetermined region is calculated. In accordance with the gradation of achromatic color, only the outward journey is used as the scanning direction when an image in an intermediate gradation is recorded and both of the outward and inward journeys are used when an image in the gradation except the intermediate gradation is recorded, thereby performing the printing of a high quality image at a high speed. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus, an image recording method, a control program, and a computer-readable storage medium, and more particularly, a recording head having a plurality of recording elements arranged in a predetermined direction intersects with the arrangement direction. The present invention relates to an image recording apparatus, an image recording method, a control program, and a computer-readable storage medium, which can prevent deterioration of image quality caused by the scanning direction when an image is recorded while reciprocally scanning on a recording medium in a predetermined direction.

[0002]

2. Description of the Related Art For example, as an information output device in a word processor, a personal computer, a facsimile, etc., there is an image recording device for recording desired information such as characters and images on a sheet-shaped recording medium such as paper or film.

Although various methods are known as recording methods for image recording apparatuses, they are capable of non-contact recording on a recording medium such as paper, easy colorization, and quietness. Inkjet systems have been receiving a great deal of attention in recent years, and as a configuration thereof, a recording head that ejects ink according to desired recording information is mounted and reciprocating scanning is performed in a direction perpendicular to the feeding direction of a recording medium such as paper. The serial recording method for recording is generally widely used because it is inexpensive and easily miniaturized.

In the serial system, an operation is performed in which a recording head (specifically, a carriage on which the recording head is mounted) is moved on a recording medium in a scanning motion to eject ink to record one line.
This is a method of forming an image by repeating an operation of transporting a recording medium in a direction orthogonal to the scanning direction (main scanning direction) of the carriage (conveying direction, sub-scanning direction) by a line width.

This ink jet recording method is one in which ink is ejected onto a recording sheet in accordance with a recording signal to perform recording, and it is widely used as a quiet recording method with low running cost. Also, in recent years, many products using a plurality of color inks and applied to a color recording apparatus have been put into practical use.

When the ink jet recording method is applied to a color image recording apparatus, the structure of the recording head is roughly classified into the following two types.

As shown in FIG. 13, the first type recording head has a large number of nozzles for ejecting ink, which are arranged linearly in the sub-scanning direction.

The recording head 100 shown in FIG. 13 (a) has nozzles 100y, 100m, for ejecting color inks of yellow, magenta, cyan and black.
FIG. 13 shows a case where 100c and 100k are arranged in one line in the sub-scanning direction so that the respective colors do not overlap each other.
As a modification of FIG. 13A, the recording head 101 of FIG. 13B has nozzles 101y, 101m and 101c for ejecting color ink arranged in a line in the sub-scanning direction, and a nozzle 101k for ejecting black ink separately. It is a thing.

FIG. 15 shows an explanation of image recording using the recording head 100 of FIG. 13 (a). FIG. 15 shows print results (first to fifth scans) at each scan when the print head 100 is used to print an image using forward and backward passes in the main scanning direction (forward scan and sub-scan). It is a thing. That is, in the image recording of FIG. 15, after a predetermined amount of paper is conveyed in the sub-scanning direction after the image is recorded in the forward path (first scan) in the main scanning direction (recording result of the first scan), the return path in the main scanning direction is performed. The process of recording the image (recording result of the second scan) is repeated in (second scan),
By performing four scans, the inks of yellow (y), magenta (m), cyan (c), and black (k) are sequentially printed in the order of y → m → c → k. It shows that the completed image portion 100a shown in FIG. 15 is obtained. When printing is performed using the print head 100 in the forward and backward passes in the main scanning direction, FIG.
The ink sequence of the completed image portion 100a shown in (4) is always recorded in the order of y → m → c → k.

That is, as is clear from FIG. 15, for yellow, magenta, and cyan, one of the recording heads is used.
Since the images of the respective colors are formed at different positions on the recording paper in the main scanning once, when the so-called secondary colors of blue, red and green are formed, the order of the color superposition is irrespective of the scanning direction of the recording head. It will be constant. For example, when forming a blue image, cyan is first printed, and then magenta is printed over it. Therefore, if the print head 100 is used, high-quality images can be obtained because color unevenness does not occur even when printing is performed in the forward scan and the backward scan of the print head. The same applies to recording using the recording head 101.

However, when the recording head having the recording element orientation as shown in FIG. 13 is used, it is necessary to increase the number of nozzles of each color in order to increase the image recording speed. If the number of nozzles is increased, the length of the recording head becomes long, the image recording apparatus becomes large, and the method of holding down the recording medium in the recording section becomes complicated, so that the cost of the recording head and the image recording apparatus increases. Causes the problem.

The second type of recording head is, for example, as shown in FIG.
5, the recording head 102k for ejecting black ink, cyan ink, magenta ink, and yellow ink,
102c, 102m, and 102y are arranged in the main scanning direction. This recording head is suitable for increasing the image recording speed because the length of the recording head does not change even if the number of nozzles for each color is increased.

FIG. 16 shows an explanation of image recording using the recording head of FIG.

FIG. 16 shows the print results (first to fourth scans) at each scan when an image is printed using the print head 102 in the forward and backward passes (forward scan and sub-scan) in the main scanning direction. ) Is shown. That is,
In the image recording of FIG. 15, after a predetermined amount of paper is conveyed in the sub-scanning direction after the image is recorded in the forward path (first scan) in the main scanning direction (recording result of the first scan), the return path in the main scanning direction (2 By repeating the process of recording an image in the (scanning) (printing result of the second scanning) and printing once in the outward path in the main scanning direction, yellow (y), magenta (m), cyan (c) And black (k) ink is k → c
It is shown that the completed image portion 102a shown in FIG. 15 is obtained by sequentially recording the images in the order of → m → y. Similarly, by performing printing once on the secondary path in the main scanning direction, yellow (y), magenta (m), cyan (c), and black (k) inks are changed from k to m.
It is shown that the completed image portion 102b shown in FIG. 15 can be obtained by sequentially overlapping and recording in the order of → c → k.

When printing is performed using the print head 102 in the forward and backward passes (forward and backward scans) in the main scanning direction, as shown in FIG. 15, the ink of the image portion 102a completed by the forward scan is used. Is always k → c → m →
In contrast to the sequential printing in the order of y, the ink of the image portion 102a completed by the backward scanning is always printed in the order of y → m → c → k.

That is, when an image is formed by alternately repeating forward scanning and backward scanning for speeding up, for example, when a so-called secondary color of blue, red and green is formed, the order of color superposition is The forward scanning and the backward scanning of the recording head 102 are different from each other, and as a result, the hue (hue) is different between the forward scanning and the backward scanning, which causes unevenness in color and greatly deteriorates the image quality. .

As described above, there are two types of recording head configurations suitable for color recording. What is suitable for speeding up the image recording apparatus is that the nozzles of each color are arranged in the scanning direction of the recording head. It is a second type recording head. However, as described above, there is a problem that color unevenness occurs in each scan due to the difference in the color superposition order between the forward scan and the backward scan of the print head.

To solve this problem, Japanese Patent Publication No. 3-54
508 discloses a method of differentiating the color processing method between the forward scan and the backward scan of the print head. However,
This method requires two types of color processing tables for forward scanning and backward scanning. Also, when recording with a normal printer, color processing is performed by the printer driver on the host computer, the image data after color processing is sent to the printer body, and the printer body receives the received image data to the recording head. The data is processed and processed together and recorded, but it is necessary to understand in advance how the image data being processed will be recorded on the printer side when performing color processing with the printer driver on the host computer. It is necessary to perform color processing with. That is, it is necessary for the host computer side to know whether the print is performed by the forward scan or the backward scan of the print head. However, in order to satisfy this requirement, a printer driver on the host computer and a recording system including the printer body are required.
The system becomes very complex.

Further, when image recording is performed by using forward and backward passes (forward scan and backward scan) in the scanning direction to increase the speed of the recording head, the color reproduction range (hue) is usually deviated, so the forward scan is performed. When the color processing is changed so that the same color reproduction range is used for the scanning and the backward scanning, the color reproduction range is narrowed, which may lead to deterioration in image quality.

[0020]

SUMMARY OF THE INVENTION The present invention has been made as a starting point to solve the above-mentioned problems of the prior art, and an object thereof is recording in which nozzles of respective colors are arranged in the scanning direction. When performing high-speed image recording using both forward scanning and backward scanning in order to improve the recording speed of the image recording that uses only one of the forward and backward movements (forward scanning or backward scanning) in the scanning direction using the head. (EN) An image recording apparatus and an image recording method capable of reducing deterioration in image quality (color unevenness) due to the ink ejection order.

[0021]

An image recording apparatus according to an embodiment of the present invention for achieving the above object has the following configuration. That is, a recording head having a plurality of recording elements arranged in a predetermined direction corresponding to inks of different tones is scanned on a recording medium in a direction intersecting the arrangement direction, and an image is formed based on image data. An image recording apparatus for recording, based on the image data,
Ink amount counting means for respectively counting the ink amounts of the different color tones required when recording the predetermined region to be scanned, and an achromatic component of the predetermined region is formed based on the respective counted ink amounts. An achromatic color component amount calculation means for calculating the ink amount, and based on the calculated achromatic color component ink amount, determines the scanning direction when recording the predetermined area using the ink of the different color tones. And a scanning direction determining means.

Here, for example, the scanning direction determining means records the predetermined area by using both the forward path and the backward path of the scanning based on the calculated gradation of the achromatic color, or Either the forward or return of scanning 1
It is preferable to determine that the predetermined area is recorded using a path.

Here, for example, it is preferable that the inks of different tones include black ink and color inks that are mixed to form an achromatic component.

Here, for example, in the color ink,
It is preferable to include three color inks of yellow ink, magenta ink, and cyan ink.

Here, for example, it is preferable that the ink amount counting means counts the number of dots of ink required for recording the image of the predetermined area for each of the inks of different tones.

Here, for example, the achromatic color gradation calculating means may calculate the amount of the first achromatic color component formed from the black ink and the second achromatic color component formed by mixing the color inks. It is preferable to determine the gradation of the achromatic color based on the amount.

Here, for example, the achromatic color gradation calculating means sets the amount of ink having the smallest amount of ink for recording the predetermined area among the plurality of inks included in the color ink to the second achromatic color. It is preferable to set the amount of the component.

Here, for example, when the amount of the first achromatic color component is larger than the first predetermined value and the amount of the second achromatic color component is larger than the second predetermined value, the scanning direction determining means In addition, it is preferable to limit the scanning direction when recording the predetermined area to one of the forward path and the backward path.

Here, for example, the predetermined area is formed by a plurality of small areas having a predetermined size, and the ink amount counting means includes the first area necessary for recording each of the small areas. The amount of the achromatic color component of 1 is counted, and then the number of the small areas whose counted value exceeds the third predetermined value is counted.
When the value exceeds the predetermined value, it is preferable that the scanning direction when printing the predetermined region using the inks of different colors is one of the forward path and the backward path of the scan.

Here, for example, when the received image data is multi-valued data, the ink amount counting means
It is preferable to count the number of dots required to record the image in the predetermined area based on the number of dots assigned in advance corresponding to the multi-valued data.

Here, for example, the color ink preferably has a recording medium penetration characteristic different from that of the black ink.

Here, for example, it is preferable that the black ink and the color ink have a function of reducing the bleeding between inks by aggregating by a chemical reaction with each other.

Here, for example, the black ink preferably contains a pigment component in the coloring material.

Here, for example, it is preferable that the recording element generates thermal energy, and the thermal energy causes a state change in the ink to eject the ink.

An image recording method according to an embodiment of the present invention for achieving the above object has the following configuration. That is, a recording head having a plurality of recording elements arranged in a predetermined direction corresponding to inks of different tones,
Scan on the recording medium in a direction intersecting the arrangement direction,
An image recording method for recording an image based on image data, the ink amount counting step of counting, based on the image data, the ink amounts of the different color tones required when recording the predetermined area to be scanned. Based on each of the counted ink amount, an achromatic color component amount calculation step of calculating the ink amount forming the achromatic color component of the predetermined region, based on the ink amount of the calculated achromatic color component, And a scanning direction determining step of determining a scanning direction when recording the predetermined area using the inks of different colors.

A control program for controlling the image recording method according to one embodiment of the present invention for achieving the above object is:
It has the following configuration. That is, a recording head having a plurality of recording elements arranged in a predetermined direction corresponding to inks of different tones is scanned on a recording medium in a direction intersecting the arrangement direction, and an image is formed based on image data. A control program for controlling an image recording method for recording, wherein the control program counts ink amounts of the different color tones required when recording the predetermined area to be scanned, based on the image data. A code of an amount counting step, a code of an achromatic color component amount calculating step of calculating an ink amount forming an achromatic color component of the predetermined area based on the respective counted ink amounts, and the calculated achromatic color component Of the scanning direction determining step for determining the scanning direction when recording the predetermined region using the inks of different colors based on the ink amount of And having a over de, a.

A computer-readable storage medium storing a control program for controlling an image recording method according to an embodiment of the present invention for achieving the above object has the following configuration. That is, a recording head having a plurality of recording elements arranged in a predetermined direction corresponding to inks of different tones is scanned on a recording medium in a direction intersecting the arrangement direction, and an image is formed based on image data. A computer-readable storage medium storing a control program for controlling an image recording method for recording, wherein the control program has the different color tone required when recording the predetermined area to be scanned based on the image data. A code of an ink amount counting step of counting the ink amounts respectively, and a code of an achromatic color component amount calculating step of calculating an ink amount forming an achromatic color component of the predetermined area based on the counted ink amounts, Based on the calculated ink amount of the achromatic component, the scanning when recording the predetermined area using the ink of the different color tone And having a code scanning direction determining step of determining the direction.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] An image recording apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

In the following description, an ink jet printer will be described as an example of the image recording apparatus, but the scope of the present invention is not limited to the described examples.

In this specification, "recording" (sometimes referred to as "printing") means not only the formation of significant information such as characters and figures, but also significant insensitivity and human visual perception. Regardless of whether or not it is actualized so as to be possible, it also represents a case where an image, a pattern, a pattern, etc. is widely formed on a recording medium or the medium is processed.

Further, the "recording medium" is not limited to paper used in a general recording apparatus, but is widely applicable to ink such as cloth, plastic film, metal plate, glass, ceramics, wood and leather. Things shall also be represented.

Further, "ink" (which may be referred to as "liquid") should be broadly construed in the same way as the definition of "recording (printing)", and when applied to a recording medium, A liquid that can be used for forming an image, a pattern, a pattern, or the like, processing a recording medium, or treating an ink (for example, solidifying or insolubilizing a coloring agent in the ink applied to the recording medium).

[Cause of color unevenness and method for reducing color unevenness:
FIG. 1] First, the cause of color unevenness and a method of reducing the color unevenness will be described.

FIG. 1 shows the gradation level of the achromatic component (InputLe
vel) yellow, magenta,
Process black obtained by mixing three colors of cyan (P
True black (TrueB) which is a black ink capable of expressing an achromatic color by one color with the CBk) component (second achromatic color component)
7 is a graph showing an example of gradation levels of an achromatic color obtained from the component k) (first achromatic color component) and process black and true black.

As shown in FIG. 1, generally in the ink jet recording, the gradation level of the low achromatic component is PCB.
k is used to form an image, the halftone area level of the achromatic color component is an image formed using both the inks of TrueBk and PCBk, and the high gradation level of the achromatic color component is True.
An image is formed only with Bk.

The method of mixing these two kinds of ink is carried out in order to carry out an optimum method of forming a black component according to a photographic image or a character image. In a photographic image, graininess is more important than sharpness, and in black characters, density and sharpness are more important than graininess. Therefore, the graininess is reduced by using PCBk for an image such as a photographic image in which low gradation is frequently used. On the other hand, in the case of high gradation such as a black character image, TrueBk is used to create an achromatic component formation curve.

FIG. 2 shows the recording head (black ink, cyan ink, magenta ink in which the nozzles 101k, 101c, 101m and 101y are arranged in the scanning direction) shown in FIG. 1B.
The following describes the color unevenness obtained when performing the forward pass and the backward pass (forward scan and sub-scan) in the main scanning direction in order to print the gradation pattern of the achromatic color component for ejecting (yellow ink).

2A to 2D show the forward scan and the forward scan using the combination of two kinds of ink (TrueBk and PCBk) at each point (a) to (d) of the gradation level of the achromatic color component shown in FIG. It shows whether or not color unevenness occurs when printing is performed by sub-scanning.

That is, FIG. 2A shows the case where the gradation level of the achromatic color component is low, and the process black (PC
Bk) shows a case where printing is performed in the forward scanning and the sub-scanning at a relatively low printing duty with a mixture ratio of three colors of yellow, magenta, and cyan being 5%, respectively.
No color unevenness occurs between the printing in the forward scan and the printing in the sub-scan.

On the other hand, FIG. 2B shows the case where the gradation level of the achromatic color component is the intermediate level, and the process black (PCB
k) shows a case where recording is performed in the forward scanning and the sub-scanning at a relatively high recording duty with a mixture ratio of the three colors of yellow, magenta, and cyan being 15%, respectively.
Color irregularity occurs between the prints of the forward scan and the sub-scan.

FIG. 2C shows another case in which the gradation level of the achromatic color component is an intermediate level, and the process black (PC
Bk) has a relatively high recording duty ratio of the three colors of yellow, magenta, and cyan of 30%, and further has a recording duty ratio of 10% for black (TrueBk) and two inks (TrueBk and PCB).
This shows a case where printing is performed in forward scanning and sub-scanning using k), and color unevenness occurs between printing in the forward scanning and sub-scanning.

On the other hand, FIG. 2D shows the case where the gradation level of the achromatic color component is high, and the case where TrueBk is used alone to perform printing in forward scanning and sub-scanning, and printing in forward scanning and sub-scanning is performed. No color unevenness has occurred between them.

Color unevenness does not occur in FIGS. 2A and 2D,
The cause of the color unevenness in FIGS. 2B and 2C is due to the difference in color superposition. That is, as described with reference to FIG. 15, when printing is performed using the print head 102 in the forward and backward passes (forward and backward scans) in the main scanning direction, the ink sequence of the image portion 102a completed using forward scan. Is always overlapped and printed in the order of k → c → m → y, whereas the image portion 102a completed by using the backward scan is recorded.
This is because the ink is always printed in the order of y → m → c → k. That is, if the order of color superimposition differs between the forward scan and the backward scan of the print head 102, the hue (hue) differs between the forward scan and the backward scan, which causes color unevenness and greatly deteriorates the image quality. The problem arises that

Further, in general, the black ink is improved in density and sharpness by lowering the permeation property of the color ink with respect to the recording medium. In addition, an ink that chemically reacts may be used for the purpose of preventing bleeding in the boundary area between the black image and the color image. As described above, the difference in the permeation characteristics and the chemical reaction between the inks may extremely aggravate the color unevenness for each scanning width in the reciprocal recording using the forward scanning and the sub-scanning. This is because when a highly penetrative color ink is recorded first, it penetrates into the paper before it reacts with the black ink that is recorded later, so the density does not rise relatively, but on the contrary, black ink is It is thought that if the color ink is recorded after recording, the color ink will be recorded with the black ink remaining on the paper surface, and the dye will be chemically reacted on the paper surface to leave an agglomerated dye, resulting in an extremely high density. To be

As described above, when printing is performed using both forward and backward scans of the print head in order to speed up image printing, the print duty of the PCBk that forms an achromatic component and TrueBk. There are cases where color unevenness occurs and cases where color unevenness does not occur depending on the composition ratio of the print duty.

The present application utilizes this characteristic to reduce color unevenness that occurs when image recording is speeded up by using both forward scanning and backward scanning of the recording head. That is, the number of print dots of ink of each color tone forming an achromatic component is calculated from the image data corresponding to the scan area for printing, and if it is determined that color unevenness is unlikely to occur, forward scan and backward scan are performed. Printing is performed on both sides, and conversely, if it is determined that color unevenness is likely to occur, printing is performed only on the forward scan or the backward scan. As the achromatic color component, it is preferable to use a first achromatic color component obtained from the number of black ink dots to be printed in a predetermined area and a second achromatic color component obtained from the number of yellow, magenta, and cyan dots in a predetermined area.

In the following embodiments, a heating element will be described as an example of a recording element for generating energy for ejecting ink, but the present invention is not limited to this, and a piezoelectric element may be used. Further, the heating element is not limited to the heating resistor, but may be any element capable of generating heat and ejecting ink.

[Inkjet printer: FIG. 3] Next,
FIG. 3 shows the appearance of the inkjet printer used in this embodiment.

A carriage 11 for mounting an ink jet cartridge, a carriage motor 12 for moving the carriage relative to a recording medium in the main scanning direction,
A flexible cable 13 for sending an electric signal from an unillustrated control unit of the inkjet device to the inkjet cartridge, a recovery unit 14 for performing recovery processing of the recording head, and a paper feed tray 1 for storing recording media in a stacked state.
5 and an optical position sensor 16 for optically reading the position of the carriage. In the inkjet device having such a configuration, the carriage 11 is serially scanned to perform printing with a width corresponding to the ejection openings (the number of nozzles) of the inkjet head, while at the time of non-recording, the recording medium is moved in a direction intersecting the main scanning direction. A predetermined amount is intermittently conveyed.

Reference numeral 141, which is a further enlargement of 14, is a suction and leaving cap, 142 is a discharge receiver for receiving the discharged processing liquid at the time of discharge recovery, 143 is a discharge receiver for receiving the discharged ink at discharge recovery, and 144 is a face. Wiping the surface Wiping the face with the wiper blade while moving in the direction of the arrow.

[Inkjet Printer Electric Control System: FIG. 4] FIG. 4 is a block diagram showing a configuration example of an electric control system of the ink jet printer shown in FIG.

Reference numeral 301 denotes a system controller for controlling the entire apparatus. Inside, a microprocessor and a storage element (ROM) as a storage medium for storing a control program are arranged. 302 is
This is a driver for driving the recording head in the main scanning direction. 304 and 305 are drivers 302, respectively
And 303 corresponding to the motor, and receives information such as speed and moving distance from the driver to operate.

Reference numeral 306 is a host computer, which is an apparatus having a transmission means for transferring information to be recorded to the recording apparatus of the present invention. The form thereof may be a computer as an information processing device, or may be a form such as an image reader. A buffer 307 is a buffer for temporarily storing data from the host computer 306.
The received data is stored until the reading of data is performed.

308 (308k, 308c, 308m,
Reference numeral 308y) is a frame memory for expanding the data to be recorded into image data, and has a memory size required for recording for each color. Here, a frame memory capable of recording one recording sheet will be described, but it goes without saying that the present invention is not limited to the size of the frame memory. 309 (309k, 309c,
309m, 309y) are buffers (storage elements) for temporarily storing the data to be printed, and the printing capacity changes according to the number of nozzles of the printing head.

Reference numeral 310 is a recording control section for appropriately controlling the recording head in response to a command from the system controller 301, and for controlling the recording speed, the number of recording data, and the like. Reference numeral 311 denotes recording heads 17k, 17c, 17m for ejecting ink, and 1
7y is a driver for driving the recording control unit 31
It is controlled by the signal from 0.

In the above configuration, the image data supplied from the host computer 306 is received by the reception buffer 30.
7, is temporarily stored, and is expanded in the frame memory for each color. Next, the expanded image data is read by the system controller 301 and expanded in the buffer 309. The print control unit 310 uses the print heads 17k,
It controls the operation of 17c, 17m, and 17y.

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

[Print Head: FIG. 5] FIG. 5 is a view of the print head used in the present embodiment as seen from the ejection port side. The print head 17k ejects black ink for each ink having a different color tone, and cyan. A recording head 17c that ejects ink, a recording head 17m that ejects magenta ink, and a recording head 17y that ejects yellow ink are arranged separately in the scanning direction of the recording head. Here, the recording head 17k that ejects black ink is 600 per inch.
Each head 17c, 17m, 17y for ejecting color ink has an ejection port array in which 1280 nozzles are arranged at a density of 1200 per inch.

An ink liquid path is provided corresponding to each ejection port, and a recording element for generating energy for ejecting ink is provided corresponding to each ejection port.

The ejection amount of the ink ejected from the ejection port is about 30 pl for black ink and about 4 pl for the other inks. Here, the ejection amount of the black ink is increased in order to achieve high density. The recording resolution in the scanning direction is 600 dpi for black ink and 1200 dpi for color ink.

[Color unevenness detection method: FIG. 6] Next, when an image is printed by alternately repeating forward and backward scans of the print head, it is detected whether or not color unevenness occurs for each scan. The method will be described.

FIG. 6A and FIG. 6B show scanning width × nozzle width (color head: 1280 dots, black head: 640 dots) of the color heads 17c, 17m, 17y and the black head 17k to be printed. It shows a method of calculating the number of recording dots in the image area.

Vertically in the data area recorded by the color head.
56 x 256 dots horizontally (/ 1200 x 1200 dpi)
The window 61 having the size of is set. Then, a window 62 having a size of 128 dots vertically × 128 dots horizontally (/ 600 × 6000 dpi) is set in the data area recorded by the black head.

The number of dots in these windows is counted by the recording control section using the image data stored in the buffer 309.

As a window scanning method, a scanning method in which the number of dots is counted by shifting the recording head in the scanning direction (the length direction of the band) in units of one line, or the length of each window in the length direction of the band is used. Every (black: 256 dots in the horizontal direction, color: 128 in this embodiment)
It is also possible to use a scanning method in which the number of recorded dots is counted by shifting to (dots).

The number of dots in the window recorded by the recording head for each color is the number of recorded dots Csd for a cyan image, the number of recorded dots Msd for a magenta image, the number Ysd of recorded dots for a yellow image, and the number Ksd of recorded dots for a black image. Is counted as. Then, True-Bk recorded with true black ink as the first achromatic component is set to Ksd. Also, color 3 is used as the second achromatic component.
The PCBk formed by the color has the lowest value of Csd, Msd, and Ysd.

Further, in the present embodiment, as an example, the threshold value A for the first achromatic color component (new black) is 1638 dots, and the threshold value B for the second achromatic color component (process black) is 6553 dots. This means that black ink is printed with a print duty of about 10% (= 128 × 128 × 0.1), and each color ink is printed with about 10% (= 256 × 256 × 0.1). It means to record at the recording duty.

The number of recording dots for the first achromatic color component and the number of recording dots for the second achromatic color component are counted at all positions of the recording area where recording is to be performed from now on. Only when the value exceeds B, the printing is performed by either the forward scanning or the backward scanning which is designated in advance to reduce the print unevenness, and when not, the forward scanning is performed.
The printing speed is increased by printing in both directions of the backward scan.

[Color irregularity detection and recording direction (reciprocal recording / one-sided recording) determination process: FIG. 7] FIG. 7 is a flowchart of the above operation.

In this embodiment, the normal printing operation is bidirectional printing in which printing is performed in both forward scanning and backward scanning, and it is determined whether or not one-way printing should be performed by interrupt processing before scanning, and if necessary, Sets a flag and executes one-way recording in a direction designated in advance.

First, in step S1, a counter for continuously determining whether or not a condition is satisfied is initialized.

Succeedingly, in a step S2, the number of dots of each color in the window is counted.

Next, in step S3, the number of black dots Ksd is set in TrueBk as the first achromatic component.

In step S4, TrueBk is the threshold value A.
= 1638 is determined. Step S4
If TrueBk is equal to or less than the threshold value A, the process proceeds to step S8 to initialize the counter, and then proceeds to step S11.

In step S11, it is determined whether or not the processing for one band has been completed. When the processing for one band is completed, the process proceeds to step S12, the interrupt processing before scanning is completed, and bidirectional printing which is a normal printing operation is performed. If the processing for one band is not completed in step S11, the process returns to step S2 and the above-described processing is repeated.

On the other hand, if the threshold value A is exceeded in step S4, the process proceeds to step S5 and the second
From MIN (C, M, Y) to PCBk as achromatic component of
After calculating, the process proceeds to step S6. Where MIN
(C, M, Y) is the minimum value of Csd, Msd, and Ysd.

In step S6, the second achromatic color component PC
It is determined whether Bk is larger than the threshold value B = 6553.
If the threshold value B is less than or equal to 6553, the process proceeds to step S8 to initialize the counter, and further, in step S11, it is determined whether or not the processing for one band is completed. If it is determined in step S11 that the processing for one band is completed, the process proceeds to step S12, the interrupt processing before scanning is completed, and bidirectional printing which is a normal printing operation is performed. If it is determined in step S11 that the processing for one band has not been completed, the process returns to step S2 and the above-described processing is repeated.

On the other hand, in step S6, the threshold value B = 6
If it exceeds 553, the process proceeds to step S7, the number of times the threshold A and the threshold B are successively exceeded is incremented, and then the process proceeds to step S9.

In step S9, it is determined whether the threshold values A and B have been exceeded four times in a row. If it is determined that the count is exceeded (Count is 4 or more), the process proceeds to step S10, and the one-way print flag is set. And
In step S12, the pre-scan interrupt process is terminated, and printing is performed in the direction designated in advance.

On the other hand, in step S9, Count
If is less than 4, the process proceeds to step S11 and the process of step S11 described above is performed.

The above operation is repeated until all recording is completed.

[Image Recording in Black Character Image Area and Gray Photo Image Area: FIG. 8] FIG. 8 shows a case where the present embodiment is applied to an image including a black character image area and a gray photo image area.
It is a figure which shows the dot number and recording direction of one achromatic component.

From the first scan to the fourth scan, since it is the black character image area, the first achromatic component TrueBk
The number of dots of the number of dots exceeds the threshold A. However,
The number of dots of PCBk, which is the second achromatic component, is zero. Therefore, since the black character image area is an area in which color unevenness does not occur, printing can be performed using the forward path and the backward path (forward scan and sub-scan) of the print head in the main scanning direction, and thus high-speed printing is possible.

The 5th to 7th scans are gray photographic image areas, and the first achromatic component Tr
The number of dots of ueBk exceeds the threshold value A, and the number of dots of PCBk, which is the second achromatic component, also exceeds the threshold value B. Therefore, since the gray photographic image area is an area where color unevenness occurs, color unevenness can be obtained by printing in either one of the forward and backward paths in the main scanning direction of the print head, for example, in the backward path (sub-scanning). It can record high quality images.

As described above, according to this embodiment, the number of print dots of the two achromatic color components in the predetermined area within the scan to be printed is calculated, and if either one is low, the reciprocal print is performed. However, since the recording in one direction is performed only when both exceed the threshold value, it is possible to record an image with less noticeable color unevenness at high speed.

[Second Embodiment] As shown in the first embodiment, as a background of black characters, there is a region including a relatively low density gray halftone as shown in FIGS. 2B and 2C. In the case of an image, color unevenness occurs when an image is printed using both the forward and backward passes of the printhead, so printing is performed on either the forward or backward pass in the main scan direction. This is because the number of PCBk dots and TrueBk are set in a predetermined window size as shown in FIG.
It occurs to count the number of dots.

However, if a plurality of relatively small windows are provided within the predetermined window size shown in FIG. 6 and TrueBk is locally present, or T is averaged.
If the change is made so as to determine whether or not rueBk exists, an image centered on black characters in which color unevenness does not occur, for example, as shown in FIG.
In the case of D, since reciprocal recording can be performed, high-speed recording becomes possible.

In the present embodiment, an example is shown in which an image in which a region including a halftone of relatively low density gray is present on the background of such black characters and a pure photographic image are accurately discriminated.

[Method for Calculating Number of Printed Dots in Predetermined Area Corresponding to Black Data: FIG. 9] FIG. 9 shows an image in the image area of the scan width of the print head × the number of nozzles corresponding to black data to be printed. It shows a method of calculating the number of recording dots in a predetermined area of data. here,
The window 62a has vertical 16 x horizontal 16 dots (/ 600d
It is assumed that there are 64 child windows 62ac each having a size of pi).

To determine a black character, a threshold value C (= 200) is set in the child window 62ac, and the number of child windows whose dot number exceeds the threshold value C is determined. Since dots are dispersed evenly in the photo image, the threshold C is not exceeded in any of the 16 × 16 relatively small child windows. On the other hand, since black characters have dots locally, child windows that exceed the threshold value occur in places. The dot count values of the 64 child windows are Ksd1 to Ksd64.

[Recording Direction (Reciprocal Recording / One-sided Recording) Determination Processing: FIG. 10] FIG. 10 is a flowchart of this embodiment.

Note that, in FIG. 10, the flow of a large process is the same as that of the first embodiment. Therefore, the same processes as those described in FIG. 7 are designated by the same reference numerals, and the overlapping description will be omitted. Only points different from 7 will be described.

In step S101, the threshold value is set, then the process proceeds to step S2, the process of step S2 described in FIG. 7 is performed, and then the process proceeds to step S3.
After performing the process of step S2 described in FIG. 7, the process proceeds to step S4.

If TrueBk is larger than the threshold value A in step S4, steps S102 to S102 are executed.
By performing the processing of 104, it is determined whether the black dots locally exist or the dispersed black dots.

In step S102, the dot numbers Ksd1 to Ksd64 of the 64 child windows 62ac shown in FIG. 9 are counted. Subsequently, in step S103, the number SWCount of child windows whose dot count value exceeds the threshold value C = 200 is counted, and then step S10.
Go to 4.

In step S104, if the SWCount is less than the threshold value D = 8, the process proceeds to step S5, and if the threshold value D = 8 or more, the process proceeds to step S8.

The processing from step S5 and step S8 to step S12 has been described with reference to FIG.

When the SWCount is larger than the threshold value D and there is a region where the number of black dots is locally large, it is determined that the image is an image centered on the black character image, and when the interrupt process before scanning is completed, both To perform high speed recording.

As described above, according to the present embodiment, it is possible to accurately distinguish a gray halftone image having a relatively low degree of contrast and a photographic tone image on the background of black characters. Therefore, an image with less noticeable color unevenness can be recorded at high speed.

[Third Embodiment] In this embodiment, a case of processing multi-valued data will be described. Processing with higher resolution is required to realize higher quality recording. However, as the resolution becomes higher, the amount of data to be processed inside the printer becomes very large, which causes an increase in cost due to the increase in memory capacity. Therefore, a method of improving the image quality without increasing the amount of data to be processed by increasing the number of gradations is used.

[Example of processing multi-valued data: FIG. 11] For example,
If the minimum resolution of the printhead is 1200 x 1200 dpi, the resolution to be processed on the host is 600 x 60
The data amount is set to 1 by setting 4 values (2 bits) of 0 dpi.
1/2, and the binary value of 1200 × 1200 dpi (1 bi
The same image quality as in t) is obtained.

The received data of 2 bits of 600 × 600 dpi is developed and recorded in the data of the dot arrangement as shown in FIG. This expansion processing may be performed in units of one band scan, but it is also possible to reduce the required memory capacity by adopting a configuration in which expansion is performed in real time each time one column is recorded.

A case where this embodiment is applied to a device similar to the recording device used in the first embodiment will be described.

The recording resolution is Bk 6 as in the first embodiment.
00 × 600 dpi, color 1200 × 1200 dpi
i, and the data received by the printer engine unit is 600 × 600 dpi for both black and color. However, with respect to the number of gradations, Bk is binary (1 bit), while color is quaternary (2b).
it).

In order to make the window size equivalent to that of the first embodiment, Bk is 128 dots vertically × 12 pixels horizontally in this embodiment.
8 dots (/ 600 dpi) with a color of 128 vertical x 1 horizontal
The window has a size of 28 dots (/ 600 dpi). Each color pixel is processed by adding the number of dots corresponding to FIG. 11 according to the received 2-bit data.

At this time, the number of dots in the case of the reception data "11" is set to 4, but it may be changed according to the ink ejection amount. The other processing is the same as that of the first embodiment, and thus the description thereof is omitted.

As described above, with the configuration capable of counting the number of dots corresponding to multi-valued data, the amount of data to be processed can be reduced, and an image without density unevenness can be recorded at high speed.

[0118]

Other Embodiments In the first to third embodiments, FIG.
The application to the print system including the host computer and the printer including the printer engine control unit as shown in FIG.

In particular, a mode has been described in which binary or multi-valued raster data is received from the host computer and the engine control unit processes the data for one scan band.

The present invention may further be a print system configured to generate an intermediate language on the host and process it into raster data by an image processing controller section provided on the printer side, as shown in FIG. 12B. .

Although the embodiments have been described in detail above, the present invention may be applied to a system composed of a plurality of devices or may be applied to an apparatus composed of a single device.

The present invention supplies a software program (in this embodiment, a program corresponding to the flowcharts shown in FIGS. 7 and 10) for realizing the functions of the above-described embodiment directly or remotely to a system or apparatus. However, the case where it is also achieved by the computer of the system or the apparatus reading and executing the supplied program code is included. In that case, the form need not be a program as long as it has the functions of the program.

Therefore, the program code itself installed in the computer to implement the functional processing of the present invention by the computer also implements the present invention. That is, the claims of the present invention include the computer program itself for realizing the functional processing of the present invention.

In this case, the program may take any form such as an object code, a program executed by an interpreter, or script data supplied to an OS as long as it has the function of the program.

A recording medium for supplying the program is, for example, a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, an MO, a CD.
-ROM, CD-R, CD-RW, magnetic tape, non-volatile memory card, ROM, DVD (DVD-ROM,
DVD-R).

In addition, as a method of supplying the program,
It can also be supplied by connecting to a homepage on the Internet using a browser of a client computer, and downloading the computer program itself of the present invention or a compressed file having an automatic installation function from the homepage to a recording medium such as a hard disk. It can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from different homepages. That is, a WWW server that allows a plurality of users to download a program file for implementing the functional processing of the present invention on a computer is also included in the claims of the present invention.

Also, by encrypting the program of the present invention, C
By storing the information in a storage medium such as a D-ROM and distributing it to the user, and having the user who satisfies the predetermined conditions download the key information for decrypting the encryption from the home page via the Internet, and by using the key information It is also possible to execute the encrypted program and install the program in a computer to realize it.

Further, the computer executes the read program to realize the functions of the above-described embodiments, and the OS and the like running on the computer execute the actual processing based on the instructions of the program. The function of the above-described embodiment can be realized also by performing a part or all of the above.

Further, after the program read from the recording medium is written in the memory provided in the function expansion board inserted in the computer or the function expansion unit connected to the computer, based on the instruction of the program,
CPU provided on the function expansion board or function expansion unit
Performs a part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

As described above, according to the present invention, in the recording apparatus in which the recording heads ejecting the respective color inks are arranged in the scanning direction, the number of recording dots of each color is counted from the image data of the predetermined area and the recording direction is determined. In order to determine the,
When it is determined that color unevenness is unlikely to occur, reciprocal recording is performed to enable high-speed recording. In addition, when it is determined that color unevenness is likely to occur, it is possible to perform one-way recording and minimize a decrease in recording speed.

When recording an image in a predetermined area in the scanning direction based on the image data, the ink amounts necessary for recording the image are counted, respectively, and the achromatic color of the predetermined area is calculated based on the counted ink amount. Tones are calculated, and in accordance with the obtained achromatic color gradation, only the forward path is used as the scanning direction when recording an image in the case of intermediate gradation, and the image is recorded in cases other than intermediate gradation. By using both the forward path and the backward path as the scanning direction at that time, a high-speed and high-quality image is recorded.

[0132]

As described above, according to the present invention,
In order to improve the recording speed of image recording using only one of the forward path or the backward path (forward scan or backward scan) in the scanning direction by using the print head in which the nozzles of each color are arranged in the scan direction, It is possible to provide an image recording apparatus and an image recording method that can reduce image quality deterioration (color unevenness) due to the ink ejection order that occurs when high-speed image recording is performed using both of them.

[Brief description of drawings]

FIG. 1 shows PCBk and T with respect to the gradation level of an achromatic color component.
It is a figure showing an example of the compounding ratio of rueBk.

FIG. 2A is a diagram illustrating an example in which color unevenness does not occur in a low-density area when reciprocal recording is performed by a horizontally aligned head.

FIG. 2B is a diagram illustrating an example in which color unevenness occurs in an intermediate density region when reciprocal recording is performed by a horizontally aligned head.

FIG. 2C is a diagram illustrating another example in which color unevenness occurs in a low-density area when reciprocal recording is performed by a horizontally aligned head.

FIG. 2D is a diagram illustrating an example in which color unevenness does not occur in a high-density area when reciprocal recording is performed by a horizontally aligned head.

FIG. 3 is a diagram showing an overview of an inkjet printer according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration example of an electric control system of the inkjet printer.

FIG. 5 is a diagram of a recording head according to an embodiment of the invention as viewed from an ejection port side.

FIG. 6 is a diagram illustrating a method of counting the number of print dots required for printing a predetermined area in an image area of one band.

FIG. 7 is a flowchart of a process for determining whether to use both forward and backward scanning directions in the scanning direction or only one of them in the first embodiment.

FIG. 8 is a diagram illustrating a recording operation when recording a predetermined image and a type of a colorless component used.

FIG. 9 is a diagram illustrating a method of dividing a predetermined area in a one-band image area into smaller areas and counting the number of recording dots for each of the smaller areas in the second embodiment.

FIG. 10 is a flowchart of a process for determining whether to use both forward and backward scanning directions in the scanning direction or only one of them in the second embodiment.

FIG. 11 is a diagram showing a development pattern of multi-valued data in the third embodiment.

FIG. 12 is a diagram showing a printing system to which the present invention can be applied.

FIG. 13 is a diagram illustrating a configuration of a recording head of an inkjet printer.

FIG. 14 is a diagram illustrating the configuration of another recording head of the inkjet printer.

FIG. 15 is a diagram illustrating an image recording method using a recording head.

FIG. 16 is a diagram illustrating an image recording method using another recording head.

[Explanation of symbols]

1 ... Current determination unit 2, 102 ... Constant current control IC 3, 103 ... Switch MOS transistor 4 ... Inductor 5: Free wheeling diode 6 ... Output capacitor 7: Input capacitor 8: voltage dividing resistor 1 9: voltage dividing resistor 2 10 ... Wave shaping section 11 ... Pulse counting section

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takumi Kaneko             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 2C056 EA04 EA05 EA11 EB49 EC11                       EC75 EE03 EE10 EE14 FA03                       FA11

Claims (17)

[Claims] 1. A recording head, which has a plurality of recording elements arranged in a predetermined direction corresponding to inks of different tones, is made to scan on a recording medium in a direction intersecting with the arrangement direction, and based on image data. An image recording apparatus for recording an image by means of an ink amount counting means for respectively counting the ink amounts of the different color tones required when recording the predetermined area to be scanned, based on the image data, Based on the counted ink amount, an achromatic color component amount calculation means for calculating the ink amount forming the achromatic color component of the predetermined region, and based on the calculated achromatic color component ink amount, the different color tone An image recording apparatus comprising: a scanning direction determining unit that determines a scanning direction when recording the predetermined area using ink. 2. The scanning direction determining means records the predetermined area by using both the forward path and the backward path of the scan based on the calculated gradation of the achromatic color, or the forward path of the scan. The image recording apparatus according to claim 1, wherein it is determined that the predetermined area is recorded by using one of the returning paths. 3. The image recording apparatus according to claim 1, wherein the different color tones include a black ink and a color ink mixed to form an achromatic component. 4. The image recording apparatus according to claim 3, wherein the color inks include three color inks of yellow ink, magenta ink, and cyan ink. 5. The ink amount counting means counts the number of dots of ink required to record an image of the predetermined area for each of the inks of different tones. The image recording apparatus according to claim 4. 6. The achromatic color component amount calculation means is based on an amount of a first achromatic color component formed from the black ink and an amount of a second achromatic color component formed by mixing the color inks. The image recording apparatus according to claim 3, wherein the gradation of the achromatic color is determined. 7. The achromatic color component amount calculating means determines the amount of ink having the smallest amount of ink for recording the predetermined area among the plurality of inks included in the color ink as the amount of the second achromatic color component. The image recording apparatus according to claim 6, wherein: 8. The scanning direction determining means, when the amount of the first achromatic color component is larger than a first predetermined value and the amount of the second achromatic color component is larger than a second predetermined value. 7. The image recording apparatus according to claim 6, wherein the scanning direction when recording the predetermined area is limited to one of the forward path and the backward path. 9. The predetermined area is formed by a plurality of small areas having a predetermined size, and the ink amount counting means is provided with the first blank area required for recording of each of the small areas. The amount of the coloring component is counted, and then the number of the small areas whose counted value exceeds the third predetermined value is counted, and the scanning direction determining means determines the different color tone when the number exceeds the fourth predetermined value. 7. The direction of the scanning when recording the predetermined area using the ink of claim 1 is one of the forward path and the backward path of the scanning.
The image recording device described in 1. 10. The ink amount counting means, when the received image data is multi-valued data, calculates the image of the predetermined area based on the number of dots pre-allocated corresponding to the multi-valued data. The image recording apparatus according to claim 5, wherein the number of dots required for recording is counted. 11. The image recording apparatus according to claim 3, wherein the color ink has a recording medium penetration characteristic different from that of the black ink. 12. The image recording apparatus according to claim 3, wherein the black ink and the color ink have a function of reducing the bleeding between inks by aggregating due to a chemical reaction with each other. 13. The image recording apparatus according to claim 3, wherein the black ink contains a pigment component as a coloring material. 14. The recording element generates thermal energy, and the thermal energy causes a state change in the ink to eject the ink. Image recording device. 15. A recording head having a plurality of recording elements arranged in a predetermined direction corresponding to inks of different tones is scanned on a recording medium in a direction intersecting with the arrangement direction, and based on image data. An image recording method for recording an image, wherein, based on the image data, an ink amount counting step of counting the ink amounts of the different color tones required when recording the predetermined area to be scanned, respectively. Based on the counted ink amount, an achromatic color component amount calculation step of calculating the ink amount forming the achromatic color component of the predetermined region, based on the calculated achromatic color component ink amount, of the different color tones And a scanning direction determining step of determining a scanning direction when recording the predetermined area using ink. 16. A recording head, which has a plurality of recording elements arranged in a predetermined direction corresponding to inks of different colors, is made to scan on a recording medium in a direction intersecting with the arrangement direction, and based on image data. Is a control program for controlling an image recording method for recording an image, wherein the control program, based on the image data, the ink amount of the different color tones required when recording the predetermined area to be scanned, respectively. A code of an ink amount counting step of counting, a code of an achromatic color component amount calculating step of calculating an ink amount forming an achromatic color component of the predetermined area, based on the respectively counted ink amount, and the calculated A scanning direction determination that determines the scanning direction when recording the predetermined area using the inks of different colors based on the amount of ink of the achromatic component. Control program for controlling an image recording method and having a code step. 17. A recording head having a plurality of recording elements arrayed in a predetermined direction corresponding to inks of different tones is scanned on a recording medium in a direction intersecting the array direction, and based on image data. A computer-readable storage medium storing a control program for controlling an image recording method for recording an image, wherein the control program is necessary when recording the predetermined area to be scanned based on the image data. A code of an ink amount counting step of counting ink amounts of different color tones, and an achromatic color component amount calculating step of calculating an ink amount forming the achromatic color component of the predetermined area based on the counted ink amounts. When recording the predetermined area by using the ink of the different color tones based on the code and the calculated ink amount of the achromatic component Computer readable storage medium storing a control program for controlling an image recording method characterized in that it comprises a code scanning direction determining step of determining the direction of the serial scanning.