JP2003341065A - Inkjet head, imaging apparatus and imaging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an inkjet head having a tie ring line head, an imaging apparatus and an imaging method ensuring imaging with high color reproduction characteristics. <P>SOLUTION: In the imaging apparatus where a liquid drop of ink is formed and ejected by driving an inkjet head 1 having the tie ring line head 6 formed by arranging a plurality of head chips of a narrow print width and an image is formed on a recording medium 21, the inkjet head 1 comprises a means 30 for storing individual ink ejection characteristic information of the plurality of head chips or a corresponding color conversion table, and an image processing means 31 for reading out the ink ejection characteristics information or the corresponding color conversion table from the storage means 30 of the inkjet head 1, color converting the RGB image data into image data for printing depending on the ink ejection characteristics of each head chip and generating the driving signal of the inkjet head 1. <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 ink jet head having a tiling line head formed by arranging a plurality of head chips having a narrow printing width, an image forming apparatus, and an image forming method, and more particularly, to high color reproduction characteristics. The present invention relates to an inkjet head, a print forming apparatus, and a print forming method capable of forming an image with less unevenness between chips.

[0002]

2. Description of the Related Art Generally, in an input device such as a digital camera or an image scanner, an input image is converted into R (red) and G
Data is obtained by color-separating into three components of (green) and B (blue), and image data is expressed using three parameters of R, G, and B even in a display device such as a CRT or LCD. On the other hand, in a printer or printing machine, since an image is formed using inks such as C (cyan), M (magenta), Y (yellow), and K (black), R
It is necessary to convert the GB image data into CMYK image data for printing, and the color conversion algorithm determines the color reproduction characteristics of the printer or the like.

The simplest of these color conversion algorithms is a color conversion system using a so-called linear first-order polynomial. Although this method has an advantage that it requires less resources, it is not suitable for a printer having a strong non-linearity such as an inkjet printer, because the variable that can be adjusted is limited. Therefore, as a color conversion algorithm with higher reproducibility, a color conversion method using a lookup table (hereinafter abbreviated as “LUT”) method is used. What is the color conversion method by the LUT method?
Experimentally or theoretically obtain the correspondence between the input value and the output value, and describe the correspondence,
It is a method of obtaining an output value for a certain input value by referring to it.

In the color conversion by the LUT method, it is possible to improve the accuracy of the color reproduction characteristic, but it is necessary to hold the data corresponding to the gradation of the input image data. For example, RGB constituting the input image data can be held. When each color has a gradation of 8 bits, it is necessary to hold approximately 16.7 million pieces of data, and actually measuring such a large amount of data is very time-consuming and is actually performed. Absent. In general, as shown in FIG. 6, the gradations of the RGB colors forming the image data are thinned out at appropriate intervals and, for example, 9 × 9 × 9 correspondences between input values and output values are sampled 3 Dimension LUT (hereinafter referred to as "3D-LUT")
Is generated and an output value for a certain input value is obtained by referring to this 3D-LUT.

When an input value P included in the RGB image data is not located on the grid point of the 3D-LUT shown in FIG. 6, the input value P is dealt with by an interpolation method such as a cubic interpolation method. Output value. As the procedure, first, an input value P included in RGB image data
Is included in the small unit cube divided in the 3D-LUT. Input value P here
Is, for example, as shown in FIG. 7, grid points P ₁ , P ₂ , ..., P
It is assumed to be contained inside the unit cube surrounded by ₈ .
Next, the unit cube containing the input value P is divided into _eight rectangular parallelepipeds V _{1 to} V ₈ by the input value P, and the weighted average is obtained. Thereby, the output value with respect to the arbitrary input value P can be calculated. Then, the RGB image data can be color-converted into CMYK image data by performing the same calculation on all the input values P included in the RGB image data. So with less resources,
It is possible to obtain CMYK image data for printing to be directly converted as an output value for an arbitrary input value P.

In the above description, the 3D-L shown in FIG.
The UT has been described as a color conversion table created so as to directly convert an output value with respect to an arbitrary input value P, but there are other examples in which it is applied. For example, C, M,
Assuming that the gradation characteristics of Y and K colors are straight lines with respect to a visually uniform scale, a 3D-LUT for converting RGB image data into CMYK image data is created, and the 3D-LUT is created.
After conversion using the D-LUT, a table is prepared separately for conversion so as to match the actual gradation characteristics of each of C, M, Y, and K, and the output value to be actually converted is obtained using this table. Good. In this case, the gradation of each color of C, M, Y, K is 8
Even in the case of bits, it is sufficient to prepare 1024 pieces of data for four colors, and even if the gradation characteristic of the output device is non-linear, it can be tabulated faithfully. Therefore, if a LUT and various parameters for performing color conversion from RGB image data to CMYK image data are prepared for each printing mode and type of recording paper, a printer with strong non-linearity such as an inkjet printer can also be used. It is possible to faithfully express gradation.

[0007]

However, such a conventional image forming method using a color conversion algorithm is compatible with an inkjet head having a so-called tiling line head and an image forming apparatus which have been developed in recent years. It wasn't something. As shown in FIG. 8, the tiling line head is formed by arranging a plurality of head chips having a narrow print width so as to correspond to inks of respective colors Y, M, C, and K. There are slight differences in the ink ejection characteristics, such as the size of the nozzles that eject the ink and the direction in which the ink is ejected, and they are not uniform as a whole. Therefore, when an image forming method using a conventional color conversion algorithm is applied, uneven density or the like may occur depending on the printing area of the printing paper. For example,
As shown in FIG. 8, in a certain print area A2, the print area A1
May be printed lighter than the other printing area A3, may be printed darker than the printing area A1 in the other printing area A3, and color fog may occur due to specific ink in the other printing area A4.
There is a problem that the color reproduction characteristics of the printing result are not good.

In view of the above, the present invention addresses such a problem, and in an ink jet head having a tiling line head formed by arranging a plurality of head chips having a narrow printing width, the color reproduction characteristic is high and the unevenness between the chips is high. It is an object of the present invention to provide an inkjet head, a print forming apparatus, and a print forming method capable of forming an image with less image.

[0009]

In order to achieve the above object, an inkjet head according to the present invention comprises a tiling line head having a wide printing width formed by arranging a plurality of head chips having a narrow printing width, and the tiling. An ink jet head comprising: a drive circuit for driving a plurality of head chips forming a line head to control ink ejection; and an ink ejection characteristic information of each of the plurality of head chips or a color conversion table corresponding thereto. And a storage means for storing.

With this configuration, the storage means
Ink ejection characteristic information of each of a plurality of head chips or a color conversion table corresponding thereto is stored.

Further, the image forming apparatus according to the present invention drives an ink jet head having a tiling line head having a wide printing width, which is formed by arranging a plurality of head chips having a narrow printing width, and makes ink droplets from its nozzles. In an image forming apparatus that ejects and forms an image on a recording medium, the inkjet head includes a storage unit that stores ink ejection characteristic information of each of a plurality of head chips or a color conversion table corresponding thereto. Ink ejection characteristic information or a color conversion table corresponding thereto is read from the storage means, the RGB image data is color-converted into image data for printing in accordance with the ink ejection characteristic information of each head chip, and the drive signal of the inkjet head is obtained. It is provided with an image processing means for generating.

With such a configuration, the image processing means reads out the ink ejection characteristic information of each of a plurality of head chips stored in the storage means of the ink jet head or the color conversion table corresponding to the information, and the head chip of each head chip is read. The RGB image data is color-converted into image data for printing in accordance with the ink ejection characteristic information, and a drive signal for the inkjet head is generated. As a result, variations in printing results due to the tiling line head formed by arranging a plurality of head chips having a narrow printing width are reduced, and an image having high color reproduction characteristics can be formed.

Further, in the image forming method according to the present invention, an ink jet head having a tiling line head having a wide printing width, which is formed by arranging a plurality of head chips having a narrow printing width, is driven to form ink droplets from the nozzle. In an image forming method of ejecting and forming an image on a recording medium, ink discharge characteristic information of each of a plurality of head chips is stored in a storage unit provided in the inkjet head, and the stored ink discharge characteristic information is stored. Is read from the storage means, and the RGB image data is color-converted into printing image data for each head chip by referring to a look-up table corresponding to the ink ejection characteristic information.

By carrying out such a method, the RGB image data is color-converted into image data for printing in accordance with the ink ejection characteristic information of each of the plurality of head chips. As a result, variations in printing results due to the tiling line head formed by arranging a plurality of head chips having a narrow printing width are reduced, and an image having high color reproduction characteristics can be formed.

An image forming method according to another embodiment of the present invention drives an ink jet head having a tiling line head having a wide printing width, which is formed by arranging a plurality of head chips having a narrow printing width, and ejects ink from the nozzles. In an image forming method for forming an image on a recording medium by forming droplets and ejecting, a color conversion table according to ink ejection characteristic information of each of a plurality of head chips is stored in a storage unit provided in the inkjet head. Then, the stored color conversion table is read from the storage means, and the RGB image data is color-converted into image data for printing for each head chip by using this color conversion table as a lookup table.

By carrying out such a method, the RGB image data is color-converted into image data for printing in accordance with the ink ejection characteristic information of each of the plurality of head chips. As a result, variations in printing results due to the tiling line head formed by arranging a plurality of head chips having a narrow printing width are reduced, and an image having high color reproduction characteristics can be formed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an inkjet head 1 according to the present invention and the inkjet head 1.
FIG. 3 is a perspective view showing an embodiment of a printer 2 in which is mounted. FIG. 1 shows a type in which the inkjet head 1 has an independent form and is directly attached to the printer 2. Then, the inkjet head 1 is housed as shown by an arrow H and set in the printer 2 in a fixed state to form an image forming apparatus, for example, an inkjet printer.

The ink jet head 1 forms a liquid ink into fine droplets by, for example, an electrothermal conversion type or an electromechanical conversion type and ejects the ink to form ink dots on a recording medium such as recording paper. Cartridge 3 and
A print head 4, a drive circuit 5 (see FIG. 3), and a storage means 30 (see FIG. 4).

The ink cartridge 3 contains a plurality of colors of ink inside, and its casing is elongated in the width direction of the printer 2 over the entire width. Inside the ink cartridge 3, there are, for example, four ink storage chambers filled with four color inks, for example, Y (yellow), M (magenta), C (cyan), and K (black). There is. The ink cartridge 3 is made of hard resin or the like.

A print head 4 is provided on the bottom surface of the ink cartridge 3. This print head 4
2 is for making ink supplied from the ink cartridge 3 into fine liquid droplets and ejecting them, and a so-called tiling line head 6 is formed as shown in FIG. As shown in FIG. 2, the tiling line head 6 is a line head having a wide printing width formed by arranging a plurality of head chips 7, 7, ... Having a narrow printing width. Further, the head chips 7 constituting the tiling head 6 are arranged in a row on the dry film 9 made of carbon-based resin having a predetermined shape so as to correspond to the inks of the respective colors YMCK.

On the lower surface of the dry film 9, a sheet-shaped orifice plate 1 made of, for example, carbon resin is used.
No. 0 is provided, and a nozzle 8 (see FIG. 3) for ejecting ink is formed on the orifice plate 10. As shown in FIG. 2, such a tiling line head 6 is attached to the metal plate member 11 formed with an ink flow path 15 (not shown) (see FIG. 3), and the ink shown in FIG. It is connected to the lower surface of the cartridge 3.

The drive circuit 5 drives a plurality of head chips 7, 7, ... Which constitute the tiling line head 6 to control ink ejection. As shown in FIG.
The heating of the heater 12 is controlled so as to eject ink droplets from the nozzles 8 formed on the orifice plate 10, and is formed on the silicon substrate 13 that constitutes the head chip 7, for example. The dry film 9 that is sandwiched between the head chip 7 and the orifice plate 10 and separates them has a comb-shaped shape that serves as a partition wall of the heaters 12 formed side by side on the silicon substrate 13. Ink liquid chamber 1 around 12
4 is formed. An ink flow path 15 is formed on the side of the head chip 7 on the side where the ink liquid chamber 14 is open, and each ink liquid chamber 1 is formed.
Ink is led to the nozzle 4. This allows
When the heating of the heater 12 is drive-controlled by the drive circuit 5, ink droplets can be ejected from the nozzle 8. A flexible wiring board 16 having pads is connected to the drive circuit 5.

Further, in the printer 2 shown in FIG. 1, ink is made into fine droplets and ejected from the nozzles 8 (see FIG. 3) formed in the ink jet head 1 configured as described above, and the recording paper 21 or the like is ejected. This is an image forming apparatus that forms an image by spraying ink onto the recording medium, and the inkjet head 1 is driven based on the image data for printing that has been color-converted from the RGB image data.
The printer 2 is entirely housed in a rectangular parallelepiped-shaped casing 20, and the recording paper 21 can be fed by mounting a paper tray 22 storing the recording paper 21 from a tray entrance formed in the front of the printer 2. It is like this.

When the paper tray 22 is thus mounted on the printer 2 through the tray entrance / exit, the recording paper 21 is pressed against the paper feed roller 23 by a predetermined mechanism, and the rotation of the paper feed roller 23 causes the arrow A to move. As shown in, the recording paper 21 is sent out from the paper tray 22 toward the back side. A reversing roller 24 is arranged on the paper feeding side of the printer 2, and the reversing roller 2
4 is rotated and the like, as shown by arrow B, the recording paper 21
The feed direction of is switched to the front direction.

The printer 2 is provided with a spur roller 25 and the like, and the recording paper 21 whose paper feed direction is thus switched is conveyed so as to traverse below the print head 4 of the ink jet head 1. . At this time, the inkjet head 1 forms an image on the recording paper 21, and as shown by an arrow C, the image is ejected from the ejection port on the front side of the printer 2. In addition,
The printer 2 is configured such that the inkjet head 1 can be replaced, as shown by an arrow H.

Here, in the present invention, as shown in FIG. 4, the storage unit 30 is provided in the ink jet head 1 having the tiling line head 6. The storage unit 30 serves as a storage unit that stores the individual ink ejection characteristic information of the plurality of head chips 7, 7, ... Which constitute the tiling line head 6 shown in FIG. It is possible to discriminate the liquid amount of ink droplets ejected from the nozzle 8 (see FIG. 3) or the density itself at the time of solid printing, or the level of individual difference such as large, medium, small, or 1 to 3 with respect to such information in multiple stages Stored as a value.

Here, the ink ejection characteristic information stored in the storage unit 30 is stored for each of the plurality of head chips 7, 7, ... Which constitute the tiling line head 6 shown in FIG. In addition, the ink ejection characteristic information includes Y, M, and
It may be stored for each color of C and K. Further, the ink ejection characteristic information may be stored for each of the print areas 1 to 4 of the head chip 7 that constitutes the tiling line head 6.

In addition, the storage unit 30 stores a gradation characteristic correction table (hereinafter referred to as "1D") as ink ejection characteristic information.
A plurality of “-LUT”) may be stored. This one
The D-LUT means the plurality of head chips 7, 7, ...
The gradation characteristic of the image data for printing is corrected for each color according to the individual ink ejection characteristic information (see FIG. 5). Specifically, the printing is performed by color conversion of RGB image data. Gradation characteristics of CMYK image data for
The correction is made for each color of C, M, Y and K. A plurality of 1D-LUTs are prepared for each ink ejection characteristic of each head chip 7 and for each printing mode and type of recording paper. However, one 1D-LUT is created with a data capacity of about 256 bytes. The storage capacity of the storage unit 30 can be smaller than that in the case of storing a color conversion table (3D-LUT) described later.

Further, according to the ink jet head 1 according to another example, a plurality of head chips 7 constituting the tiling line head 6 shown in FIG.
.. are stored in advance in accordance with the individual ink ejection characteristic information. The color conversion table stored in the storage unit 30 is a CM for printing RGB image data.
It is composed of a 3D-LUT for converting into YK image data, a 1D-LUT for correcting the gradation characteristic of CMYK image data for printing for each of C, M, Y and K colors.

The printer 2 shown in FIG.
An image processing unit 31 shown in is provided. The image processing unit 31 reads out the ink ejection characteristic information stored in the storage unit 30 of the inkjet head 1 or the color conversion table corresponding to the information, and the plurality of head chips 7, 7 ,.
It is an image processing unit that color-converts RGB image data into CMYK image data for printing according to individual ink ejection characteristic information and generates a drive signal for controlling the drive circuit 5 of the inkjet head 1. It includes a table holding unit 32, a signal conversion unit 33, and an output conversion unit 34.

Look-up table holding unit (hereinafter referred to as "LU
The “T holding unit” 32 reads out the ink ejection characteristic information or the color conversion table corresponding thereto from the storage unit 30 of the inkjet head 1 to look up a lookup table (LU).
T) as a table holding means for holding,
3D-LUT for converting GB image data into CMYK image data for printing, and 1D-for correcting gradation characteristics of CMYK image data for printing for each color of C, M, Y and K.
It holds an LUT and the like. And LU
The T-holding unit 32 has a 3D-LUT or 1D-LUT corresponding to the printing mode or the type of the recording paper 21, or a plurality of head chips 7 constituting the tiling line head 6.
1D-LU according to the ink ejection characteristic information (see FIG. 2)
T is held.

The signal conversion unit 33 refers to the LUT according to the individual ink ejection characteristic information of the plurality of head chips 7, 7, ... (See FIG. 5), and converts the RGB image data into image data for printing. The signal conversion means for conversion is shown in FIG.
When the RGB image data is received, print information such as the set printing mode and the type of printing paper 21,
, And the ink of each head chip 7, 7, ... From the LUT holding unit 32 based on the ink ejection characteristic information of the plurality of head chips 7, 7, ... (See FIG. 5) read from the storage unit 30 of the inkjet head 1. L according to the discharge characteristic information
The UT is pulled out, and the color conversion is performed by referring to the UT into CMYK image data for printing. The print information such as the print mode and the type of the print paper 21 may be added to the header of the image data, or may be directly supplied from an input panel (not shown) provided in the printer 2 shown in FIG. It may be done. In addition, these print information,
If nothing is newly given, the same value as the previous setting or the value set as the default is used.

The output conversion section 34 serves as an output conversion means for converting the CMYK image data for printing, which has been color-converted by the signal conversion section 33, into a drive signal of the drive circuit 5 of the ink jet head 1, and is shown in FIG. The CMYK image data in which the RGB image data shown is color-converted is converted into multivalued data of the number of levels according to the performance of the printing apparatus by using a halftoning means such as an error diffusion method, and then the inkjet head 1 is actually driven. It is adapted to be converted into ON and OFF signals for driving the circuit 5.

The image processing section 31 is further provided with a LUT creating section 35. This LUT creation unit 3
Reference numeral 5 is a table creating means for creating a new color conversion table based on the color conversion table, and is a 1D-LUT stored in the storage unit 30 of the inkjet head 1,
Alternatively, a new LUT is created based on the 1D-LUT held in the LUT holding unit 32.
For example, by performing data interpolation processing or by multiplying by an appropriate coefficient, based on the 1D-LUT corresponding to the specific printing mode or the type of the recording paper 21,
It can be created in a 1D-LUT corresponding to another printing mode or recording paper. Therefore, the data capacity stored in the storage unit 30 of the inkjet head 1 can be reduced, and the cost can be reduced.

Next, an image forming method by the ink jet head and the image forming apparatus thus constructed will be described. First, in FIG. 1, the inkjet head 1 configured as described above is housed as indicated by an arrow H and set in the printer 2 in a fixed state. Here, it is assumed that the storage unit 30 of the inkjet head 1 stores the ink ejection characteristic information of each of the plurality of head chips 7, 7, ... (See FIG. 5) that constitute the tiling line head 6.

At this time, the image processing unit 31 shown in FIG. 4 reads the color conversion table stored in the storage unit 30 of the ink jet head 1 and holds it in the LUT holding unit 32 as an LUT. When the RGB image data is input to the signal conversion unit 33 in this state, the image processing unit 31 causes the image processing unit 31 to store a plurality of head chips 7, 7, ... Ink ejection characteristic information stored in the storage unit 30 of the inkjet head 1. Read out, refer to the LUT corresponding to this ink ejection characteristic information,
The RGB image data can be color-converted into CMYK image data for printing for each of the head chips 7, 7, ....

That is, the signal conversion unit 33 refers to the LUT held in the LUT holding unit 32, and color-converts the RGB image data into CMYK image data for printing in accordance with the ink ejection characteristic information of each head chip 7. At this time, the signal conversion unit 33, based on the ink ejection characteristic information stored in the storage unit 30, responds to the plurality of head chips 7, 7, ... The color conversion is performed for each switching portion of the head chip 7. For example, for each of the plurality of head chips 7, 7, ... Constituting the tiling line head 6 shown in FIG.
Alternatively, for each color of Y, M, C, K of the head chip 7, or for each of the print areas 1 to 4 of the head chip 7, a 1D-LUT corresponding to the head chip 7 is provided in the LUT holding unit 32.
It is possible to convert the RGB image data into CMYK image data for printing with reference to the selected image data. At this time, the color conversion may be performed by referring to the color conversion table newly created by the LUT creating unit 35 shown in FIG. 4 as the LUT.

By carrying out such a method, a plurality of head chips 7 constituting the tiling line head 6,
7, ..., RGB depending on the ink ejection characteristic information.
Image data can be color-converted into CMYK image data for printing. As a result, as shown in FIG. 5, the densities of all the print areas 1 to 4 are equalized, the occurrence of color cast due to a specific ink can be suppressed, and the ink ejection of each head chip 7, 7 ,. It is possible to eliminate density unevenness due to slight differences in characteristics. Therefore, it is possible to reduce variations in printing results due to individual differences among the plurality of head chips 7, 7, ..., And it is possible to form an image with high color reproduction characteristics.

Here, among the LUTs which are pulled out from the LUT holding unit 32 and referred to, a plurality of head chips 7, 7,
The 3D-LUT may be used as the table to be exchanged according to the individual ink ejection characteristics, but only the 1D-LUT may be used. For example, a 3D-LUT has 17 × 17 × 1.
Sampling the correspondence between 7 input values and output values, and assuming that each sampled value has a gradation of 8 bits, the data capacity becomes about 20 KB, and the printing mode and printing paper are Depending on the number of 3D-LUTs
If it is prepared, it will be several hundred KB alone, and the capacity of the storage means (memory) required to hold it will be enormous. Moreover, the work of creating the 3D-LUT is very time-consuming. On the other hand, if only the 1D-LUT is replaced according to the ink ejection characteristic information of each head chip 7, the storage capacity of the storage unit 30 can be reduced.
Further, there is an advantage that the work of creating the 1D-LUT does not take much time.

Next, an image forming method according to another example will be described. Here, the inkjet head 1 shown in FIG.
The storage unit 30 of the tiling line head 6 shown in FIG.
It is assumed that a plurality of head chips 7, 7, ... That constitute the color conversion table according to individual ink ejection characteristic information are stored in advance. When such an inkjet head 1 is fixedly set on the printer 2 (see FIG. 1),
The image processing unit 31 shown in FIG. 3 reads out a color conversion table according to each of the plurality of head chips 7, 7, ... Ink ejection characteristic information stored in the storage unit 30, and uses the color conversion table as an LUT to print the head. The RGB image data can be color-converted into CMYK image data for printing for each of the chips 7, 7, .... As a result, as shown in FIG. 5, it is possible to reduce variations in printing results due to differences in the plurality of head chips 7, and it is possible to form an image with high color reproduction characteristics.

In the above description, the color conversion by the LUT method is shown, but the present invention is not limited to this, and the color conversion method by the linear first-order polynomial or the color conversion by the non-linear matrix calculation may be used. In this case, parameters corresponding to the printing mode, the type of recording paper, and the ink ejection characteristic information of each head chip 7 are pulled out from the LUT holding unit 32 and referred to. Although the image processing unit 31 shown in FIG. 4 is described as being provided in the printer 2, the present invention is not limited to this, and when an image forming apparatus such as a printer is connected to a personal computer or the like, The personal computer may have all or some of the same functions as the image processing unit 31. Further, the color conversion table stored in the storage means 31 of the inkjet head 1 is the entire color conversion table, but the present invention is not limited to this, and only a part or a difference thereof may be stored.

Further, the ink jet head 1 shown in FIG.
Is stored as indicated by an arrow H and set in the printer 2 in a fixed state, the image processing unit 31 causes the inkjet head 1 to move.
The ink ejection characteristic information stored in the storage unit 30 or the color conversion table corresponding thereto is read and held in the LUT holding unit 32. However, the present invention is not limited to this, and the storage unit of the inkjet head 1 is not limited to this. The ink ejection characteristic information or the color conversion table corresponding thereto may be received from 31 only when the inkjet head 1 is attached, or when printing. Only when the inkjet head 1 is attached, the information is stored in the LU.
It will be stored in the T holding unit 32. Furthermore, RG
The image data for printing that color-converts the B image data is CM
Although described as YK image data, the present invention is not limited to this, and in the case of the inkjet head 1 filled with ink of other colors such as light cyan and light magenta, their gradation characteristics are corrected for each color. 1D-LUT
May be stored and used for color conversion.

[0043]

Since the present invention is constructed as described above,
According to the ink jet head of the first aspect, the ink jet characteristic information of each of the plurality of head chips is added to the ink jet head having the tiling line head having a wide print width formed by arranging a plurality of head chips having a narrow print width. By including the storage means for storing, the storage means stores the ink ejection characteristic information of each of the plurality of head chips. By utilizing these, it is possible to perform appropriate color conversion according to the ink ejection characteristic information of each head chip of the print head, and reduce the variation in the printing result for each head chip.

According to the ink jet head of the second aspect, the gradation characteristic of the image data for printing is stored for each color in the storage means of the ink jet head according to the ink ejection characteristic information of each of the plurality of head chips. Since the gradation characteristic correction table to be corrected is stored, the storage capacity of the storage unit required for storing the gradation characteristic correction table can be reduced. Further, the gradation characteristic correction table stored in the storage means can be easily created.
It is possible to save the trouble of creating a plurality of D-LUTs.

According to the third aspect of the present invention, the ink ejection characteristic information stored in the storage means of the ink jet head is recorded for each of a plurality of head chips or each color of a plurality of head chips. Alternatively, by being stored for each print area of a plurality of head chips, appropriate color conversion is performed according to the ink ejection characteristics of each of the plurality of head chips.

Further, according to the ink jet head of the sixth aspect, in the ink jet head having the tiling line head having a wide printing width formed by arranging a plurality of head chips having a narrow printing width, each of the plurality of head chips is provided. By including the storage means for storing the color conversion table according to the ink ejection characteristic information of
A color conversion table is stored. By utilizing these, it is possible to perform appropriate color conversion according to the ink ejection characteristic information of each head chip of the print head, and reduce the variation in the printing result for each head chip.

Further, according to the ink jet head of the seventh aspect, the color conversion table stored in the storage means is a gradation characteristic correction table for correcting the gradation characteristic of the image data for printing for each color. By using these, it is possible to perform appropriate color conversion according to the gradation characteristics of the print head. Further, the gradation characteristic correction table stored in the storage means can be easily created, and the labor of creating a plurality of 3D-LUTs can be omitted.

Further, according to the image forming apparatus of the eighth and ninth aspects, a plurality of heads are provided in an ink jet head having a tiling line head having a wide printing width formed by arranging a plurality of head chips having a narrow printing width. Ink ejection characteristic information for each chip or a color conversion table corresponding thereto is provided, and the ink ejection characteristic information or the color conversion table corresponding to the ink ejection characteristic information is read out from the storage means of the inkjet head, and the ink ejection characteristics of each head chip By including the image processing means for converting the RGB image data into the image data for printing according to the information and generating the drive signal of the inkjet head, the image processing means stores the image data in the storage means of the inkjet head. Ink ejection characteristic information of each of the plural head chips that have been formed It reads the color conversion table, color conversion to image data for printing an RGB image data in accordance with the ink ejection characteristic information of each of the head chips can generate a drive signal of the ink jet head. This allows
It is possible to reduce variations in the printing result by the tiling line head formed by arranging a plurality of head chips having a narrow printing width, and to form an image with high color reproduction characteristics.

Further, according to the image forming apparatus of the tenth aspect, the image processing means is provided with the table creating means for creating a new color conversion table based on the color conversion table. It is possible to create an LUT corresponding to another printing mode or recording paper based on the LUT corresponding to the type of recording paper. Therefore, it is possible to reduce the amount of data stored in the storage unit of the inkjet head, and it is possible to reduce the cost.

Further, according to the image forming method of the eleventh and twelfth aspects, a memory provided in an ink jet head having a tiling line head with a wide printing width, which is formed by arranging a plurality of head chips with a narrow printing width. Means for storing ink ejection characteristic information of each of a plurality of head chips, read the stored ink ejection characteristic information from the storage means, and refer to a look-up table according to the ink ejection characteristic information for each head chip. By converting RGB image data into image data for printing,
The RGB image data can be color-converted into image data for printing according to the ink ejection characteristic information of each of the plurality of head chips. As a result, variations in printing results due to the tiling line head formed by arranging a plurality of head chips having a narrow printing width are reduced, and an image having high color reproduction characteristics can be formed.

According to the image forming method of the thirteenth to fifteenth aspects, the storage means provided in the ink jet head having the wide tiling line head formed by arranging a plurality of head chips having a narrow printing width. In addition, a color conversion table corresponding to the ink ejection characteristic information of each of a plurality of head chips is stored, the stored color conversion table is read from the storage means, and this color conversion table is used as a lookup table for each head chip. To RGB
By color-converting the image data into the image data for printing, the RGB image data can be color-converted into the image data for printing in accordance with the ink ejection characteristic information of each of the plurality of head chips. As a result, variations in printing results due to the tiling line head formed by arranging a plurality of head chips having a narrow printing width are reduced, and an image having high color reproduction characteristics can be formed.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of an inkjet head and a printer equipped with the inkjet head according to the present invention.

FIG. 2 is an exploded perspective view of a tiling line head forming a print head of the inkjet head shown in FIG.

FIG. 3 is a perspective view showing a structure of a head chip and its surroundings that constitute the tiling line head.

FIG. 4 is a block diagram showing a configuration of the inkjet head and an image processing unit.

FIG. 5 is an explanatory diagram showing color reproduction characteristics of an image formed on a recording sheet by the inkjet head.

FIG. 6 is a 3D image used in color conversion by the LUT method.
It is explanatory drawing which shows the concept of LUT.

FIG. 7 is a diagram illustrating a cubic interpolation method for interpolating an input value that is not located at a grid point of the 3D-LUT.

FIG. 8 is an explanatory diagram showing color reproduction characteristics of an image formed on a recording sheet by a conventional inkjet head.

[Explanation of symbols]

1 ... Inkjet head 2 ... Printer 4 ... Print head 5 ... Drive circuit 6 ... Tiling line head 7 ... Head chip 8 ... Nozzle 30 ... Storage unit 31 ... Image processing unit 32 ... LUT holding unit 33 ... Signal converter 34 ... Output converter 35 ... LUT creation section

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Claims (15)

[Claims] 1. A tiling line head having a wide printing width formed by arranging a plurality of head chips having a narrow printing width, and a plurality of head chips constituting the tiling line head are driven to control ink ejection. An ink jet head comprising a drive circuit, wherein the ink jet head is provided with storage means for storing ink ejection characteristic information of each of the plurality of head chips. 2. The storage means stores a gradation characteristic correction table for correcting the gradation characteristic of image data for printing for each color according to the ink ejection characteristic information of each of the plurality of head chips. The inkjet head according to claim 1, wherein: 3. The ink jet head according to claim 1, wherein the ink ejection characteristic information is stored for each of the plurality of head chips. 4. The ink jet head according to claim 1, wherein the ink ejection characteristic information is stored for each color of the plurality of head chips. 5. The ink jet head according to claim 1, wherein the ink ejection characteristic information is stored for each printing area of the plurality of head chips. 6. A tiling line head having a wide printing width formed by arranging a plurality of head chips having a narrow printing width, and a plurality of head chips forming the tiling line head are driven to control ink ejection. An inkjet head comprising a drive circuit, comprising: a storage unit that stores a color conversion table according to ink ejection characteristic information of each of the plurality of head chips. 7. The ink jet recording apparatus according to claim 6, wherein the color conversion table stored in the storage means is a gradation characteristic correction table for correcting the gradation characteristic of image data for printing for each color. head. 8. An ink jet head having a tiling line head having a wide print width formed by arranging a plurality of head chips having a narrow print width is driven, and ink is formed into droplets from the nozzle to eject the ink, thereby forming an image on a recording medium. In the image forming apparatus for forming, the ink jet head is provided with a storage unit for storing ink ejection characteristic information of each of a plurality of head chips or a color conversion table corresponding thereto, and the ink ejection characteristic information is stored from the storage unit of the ink jet head. Alternatively, there is provided an image processing means for reading a color conversion table corresponding thereto, color-converting the RGB image data into image data for printing in accordance with the ink ejection characteristic information of each head chip, and generating a drive signal for the inkjet head. An image forming apparatus characterized by the above. 9. The image processing means reads out the ink ejection characteristic information or a color conversion table corresponding thereto from the storage means of the ink jet head and holds it as a look-up table, and a plurality of head chips individually. Signal conversion means for color-converting RGB image data into image data for printing by referring to a look-up table according to the ink ejection characteristic information, and output conversion for converting the image data for printing into a drive signal of an inkjet head. 9. An image forming apparatus according to claim 8, further comprising means. 10. The image forming apparatus according to claim 9, wherein the image processing means comprises a table creating means for creating a new color conversion table based on the color conversion table. 11. An image is formed on a recording medium by driving an ink jet head having a tiling line head having a wide printing width formed by arranging a plurality of head chips having a narrow printing width and ejecting the ink as droplets from the nozzle. In an image forming method for forming an ink, ink storage characteristic information of each of a plurality of head chips is stored in a storage unit provided in the inkjet head, and the stored ink discharge characteristic information is read from the storage unit. An image forming method characterized in that RGB image data is color-converted into image data for printing for each head chip by referring to a look-up table corresponding to ejection characteristic information. 12. The color conversion is performed by correcting the gradation characteristic of image data for printing for each color according to the ink ejection characteristic information of each of the plurality of head chips. The image forming method described. 13. An ink jet head having a tiling line head having a wide printing width formed by arranging a plurality of head chips having a narrow printing width is driven, and ink is formed into droplets from the nozzles and ejected to form an image on a recording medium. In an image forming method for forming, a color conversion table corresponding to ink ejection characteristic information of each of a plurality of head chips is stored in a storage unit provided in the inkjet head, and the stored color conversion table is stored in the storage unit. Read from,
An image forming method, wherein RGB image data is color-converted into image data for printing for each head chip by using this color conversion table as a lookup table. 14. The image forming method according to claim 13, wherein the color conversion is performed by correcting gradation characteristics of image data for printing for each color. 15. The color conversion is performed by using a new color conversion table created based on the color conversion table as a lookup table.
Or the image forming method described in 14.