JPH10119362A - Recorder and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent striped irregularities and to record an image having good gradation by a method wherein two recording heads that are scanned in a paper width direction for recording are disposed away from each other at a predetermined distance in a paper conveying direction and the recording heads are cooperatively controlled to be driven. SOLUTION: This device comprises a paper supplying section 36 and a paper discharge roller 37 as conveying means for conveying a recording medium 35 by each predetermined length and first and second recording heads 31A, 31B having two or more kinds of recording agents having different concentrations in each similar color and being scanning in a direction perpendicular to the conveying direction of the recording medium 35. The recording heads 31A, 31B are disposed away from each other in the conveying direction at a distance which is not integral multiples of the predetermined length. The recording agent which is obtained by combining one or more agent is determined based on a pixel as the agent used for the recording of the pixel of an image having gradation and the paper supplying and recording by the recording heads 31A, 31B are controlled in accordance with the inputted image data and determined recording agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a recording apparatus for forming ink dots by discharging ink droplets and recording an image using the ink dots, and a control method of the apparatus. More specifically, the present invention relates to a printing apparatus for printing a gradation image using a plurality of inks having different densities for similar colors, and a control method of the apparatus.

[0002]

2. Description of the Related Art With the spread of information processing devices such as copying machines, word processors, computers, and communication devices, a recording head of an ink jet system is used as one of image forming (recording) devices of those devices. Those that perform digital image recording are rapidly spreading. Also,
Along with the high quality and colorization of visual information in the information processing equipment and the communication equipment, demands for high quality and colorization of recording apparatuses are increasing.

[0003] In such a printing apparatus, a plurality of printing elements are integrated and arranged in order to miniaturize pixels and the like (hereinafter, also referred to as a multi-head). In general, a plurality of multi-heads are used, for example, a plurality of multi-heads corresponding to each ink of cyan, magenta, yellow, and black for colorization.

When recording is performed using this recording head, for example, the following method is available. Now, recording elements of a predetermined width arranged in the recording head are arranged in a recording medium conveyance direction (this direction is called a sub-scanning direction), and a direction perpendicular to the sub-scanning direction (this direction is referred to as a main scanning direction). When the recording head is scanned, a recording area in which a recording element having a predetermined width is recordable in one scan is recorded, and each time recording is completed, the recording medium is moved by a predetermined feed width (predetermined width) in the sub-scanning direction. (One-pass printing). Also, a houndstooth mask is applied to an image to be output, and a mask portion (for example, a half width of a predetermined width) is used in the first scan.
After the recording medium is fed in the sub-scanning direction by half the predetermined width in the sub-scanning direction (predetermined width = predetermined width / 2), 2
There is a method in which the mask portion of the inverted zigzag lattice is printed in the second scan, and the printing medium is sent in the sub-scanning direction by a half of the predetermined width in the sub-scanning direction and is sequentially printed. In a similar procedure, for example, a method of completing printing for a predetermined width by performing scanning of a print head four times and transporting a printing medium with a feed width of 1/4 of a predetermined width (multi-pass printing), etc. Is used.

[0005] However, there is a certain limit to the high-density integration of the ink discharge ports and liquid paths, and therefore, there is also a certain limit to the miniaturization of pixels. For this reason, the dots forming each pixel become relatively large, giving a granular feeling to an image highlight portion having a low density or the like, which may cause a problem in improving the quality of the image. On the other hand, instead of increasing the integration density of the ink ejection ports and liquid paths, that is, instead of reducing the size of one pixel, the size of the ink dots to be ejected is reduced,
A so-called multi-drop method in which one pixel is formed with a number of inks corresponding to the recording density is known. In the multi-drop system, the diameter of the ink dots recorded on the recording paper can be made relatively small, so that the granularity in a low density portion such as a highlight portion can be improved. However, there is a certain limit in miniaturization of ink in consideration of the stabilization of ejection when ejecting small ink droplets, and there is also a limit in improving image quality by itself. Further, in this method, the higher the density, the more the number of inks to be ejected to one pixel increases. Therefore, a reduction in the recording speed causes a contradictory relationship between higher image quality and the recording speed.

As another method for improving the image quality without increasing the discharge port integration density, there is known a light and dark recording method using light and dark inks of similar colors having different ink densities. In this light / dark recording method, highlight portions and the like are recorded with low-density light ink, so that the granularity due to ink dots is not noticeable, and recording is performed with high-density portions with dark ink. Therefore, by increasing the number of inks to be ejected as in the multi-drop method, a high-density portion can be generated without generating a high-density portion, and a reduction in printing speed can be suppressed. In this density recording method, the ink for expressing the output image density signal level corresponding to the input image density signal is determined using, for example, a density distribution table shown in FIG.

FIG. 14 is a diagram showing an example of a shading distribution table when inks of four colors (K, C, M, and Y) are used and three types of inks (dark ink, medium ink, and light ink) are used. It is. As shown in the figure, the shading distribution table indicates the type of ink for expressing the output image density signal level corresponding to the input image density signal level. Then, when performing the recording operation, the input image is developed in accordance with the ink for expressing the output image density signal level corresponding to the input image density signal level, using the density distribution table. The density distribution table is set according to the ratio of the dye density so that the input image density signal value and the reflection density value after printing have a proportional relationship.

When the type of ink representing the output image density signal level is determined by the density distribution table,
The output image density signal level is subjected to binarization processing by a binarization circuit. For example, image signals Kconc., Kmed., Kdill., Cconc., Cmed.
Cdill., Mconc., Mmed., Mdill., Yconc., Yme
d. and Ydill. are generated.

In an image recorded by the above-described configuration, a low density area such as an image highlight portion is recorded with light ink to make ink dots inconspicuous, and a high density portion has medium ink and dark ink. Recorded in. Thereby, image quality can be improved as compared with the multi-drop method. Further, as a pseudo halftone processing method by the above-mentioned binarization processing, a dither method, an error diffusion method, an average density storage method, and the like are known.

The dither method binarizes the data of each pixel according to a threshold value for each pixel determined by a dither matrix. The error diffusion method is described in, for example, R. FLOYD & L. STEINBERG,
“AN ADAPTIVE ALGORITHM FO
R SPETUAL GRAY SCALE ”, SID
75 DIGEST, PP 36 to 37, the multi-valued image data of the target pixel is binarized (converted to the highest level or the lowest level) and the binarized level and the level before binarization are converted. The error is calculated, distributed to other pixels, and added.

The average density preservation method is, for example, as described in Japanese Patent Application Laid-Open No. 2-210962, in which already binarized binary data in the vicinity of a target pixel or a target pixel is set to black or white. A threshold value is obtained based on the binarized data, and the threshold value is used to binarize the image data of the target pixel.

[0012]

However, the conventional method described above still has some problems. For example, even in a gray-scale printing method using the same color dark and light ink having different ink densities, there is a problem that streak-like unevenness (joint streak) is easily observed at a line feed position of the print head due to a problem such as feed accuracy of the print head. there were.

Further, when a transmission image such as a medical X-ray film is to be output, the visual resolution with respect to the density is increased because of the transmission image. As a result, even when the dark and light inks are used, the density difference for each pixel is recognized, giving the impression that the image is coarse. That is,
It has become necessary to further increase the number of gradations for each pixel.

However, in order to further increase the number of gradations for each pixel, the above-described method requires an increase in the number of types of dark and light inks and a correspondingly large number of recording heads corresponding to the number of inks. That is, the cost is greatly increased. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides a recording apparatus and a control method of the apparatus which can reduce streak-like unevenness and record a good gradation image without significantly increasing cost. The purpose is to provide.

[0015]

The recording apparatus according to the present invention for achieving the above object has the following arrangement. That is, a recording apparatus that records an image on a recording medium based on input image data, a conveying unit that conveys the recording medium by a predetermined feed width, and a scanning unit that scans in a direction perpendicular to the conveying direction of the recording medium. A first recording unit that records a recording area having a predetermined width, and a first recording unit that is disposed at a position apart from the position where the first recording unit is disposed by a predetermined distance that is not an integral multiple of the predetermined feed width in the transport direction, and Second recording means for scanning and recording in a direction perpendicular to the transport direction, and control for controlling transport by the transport means and recording by the first recording means and the second recording means based on the input image data. Means.

Preferably, the first recording means and the second recording means are ink jet recording heads which perform recording by discharging ink. Preferably, the first recording unit and the second recording unit are recording heads that discharge ink using thermal energy, and include a thermal energy converter that gives the ink.

A recording apparatus according to the present invention for achieving the above object has the following configuration. That is, a recording apparatus for recording a gradation image on a recording medium based on input image data, comprising: a conveying unit for conveying the recording medium by a predetermined feed width; First recording means for recording a recording area having a predetermined width by scanning in a direction perpendicular to the conveying direction of the recording medium, the recording medium having an agent,
The recording medium is provided at a position that is not an integral multiple of the predetermined feed width in the transport direction from a position where the first recording unit is disposed, and includes a plurality of recording materials having different densities of two or more types of similar colors. A second recording unit that scans and records in a direction perpendicular to the transport direction, and a recording agent that is used for recording pixels of a gradation image to be recorded on the recording medium, based on the pixels, the first recording unit and the first recording unit. Determining means for determining a recording material obtained by combining one or more recording materials included in each of the second recording means; and transporting by the transporting means based on the input image data and the recording material determined by the determining means; A first recording unit and a control unit that controls recording by the second recording unit.

Preferably, the determining means comprises a density level which can be expressed by combining at least one of the recording materials of the first recording means and the second recording means, and a recording material which expresses the density level. Storage means for storing information relating to combinations of the above, and a multi-value conversion means for converting the input image data into multi-values based on a density level stored in the storage means, wherein a gradation image to be recorded on the recording medium is provided. The combination of the recording material expressing the density level of the pixel of the input image data multi-valued by the multi-value conversion means is obtained from the storage means to determine the recording material to be used for recording the pixel.

Preferably, the first recording means and the second recording means are ink jet recording heads which perform recording by discharging ink. Preferably, the first recording unit and the second recording unit are recording heads that discharge ink using thermal energy, and include a thermal energy converter that gives the ink.

A method for controlling a recording apparatus according to the present invention for achieving the above object has the following arrangement. That is, a method of controlling a recording apparatus that records an image on a recording medium based on input image data, wherein the transporting step transports the recording medium by a predetermined feed width, and the transport direction of the recording medium is perpendicular to the transporting direction. A first recording step of recording a recording area of a predetermined width by the first recording means for scanning, and a position separated from the position where the first recording means is installed by a predetermined distance which is not an integral multiple of the predetermined feeding width in the transport direction. And a second recording step of recording by a second recording unit which is installed and scans in a direction perpendicular to the conveying direction of the recording medium.

A control method of a recording apparatus according to the present invention for achieving the above object has the following configuration. That is, a method of controlling a printing apparatus that prints a gradation image on a printing medium based on input image data, comprising: a conveying step of conveying the printing medium by a predetermined feed width; A first recording step of having a plurality of recording agents and recording a recording area of a predetermined width by a first recording unit that scans in a direction perpendicular to the conveying direction of the recording medium; and wherein the first recording unit is provided. From the position in the transport direction to a position that is not an integral multiple of the predetermined feed width, and 2
A second recording step of recording a plurality of recording agents having different densities of at least one kind by a second recording unit that scans in a direction perpendicular to the conveying direction of the recording medium, and a gradation image recorded on the recording medium. Determining a recording material used for recording of the pixel based on the pixel by combining one or more recording materials included in each of the first recording unit and the second recording unit.

Preferably, in the determining step, a density level that can be expressed by combining at least one of the recording agents included in the first recording unit and the second recording unit, and a recording agent that expresses the density level A storage step of storing information on a combination of the two in a storage medium, and a multi-level conversion step of multi-leveling the input image data based on a density level stored in the storage medium in the storage step; The recording agent used to record the pixels of the gradation image to be recorded in the storage step is a combination of the recording agents expressing the density levels of the pixels of the input image data multi-valued in the multi-value conversion step. Obtained from the storage medium and determined.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. [Embodiment 1] First, the outline of the present invention will be briefly described. According to the present invention, by selecting two or more and 2n or less inks containing the same density ink from n kinds of different density inks to form each pixel, multi-valued pixels, that is, a process of each pixel is performed. The number of tones (the number of tones of pixels: m) is increased. Then, based on the number of gradations of the pixel, multi-value processing of the input image data, for example, multi-valued error diffusion method, m-valued average density storage method, m-valued dither matrix method, sub-matrix method, etc. A value conversion process is performed to output a gradation image. In order to realize this, two ejection means (print heads) are provided for each density ink.

Further, two recording heads provided with n ink cartridges for each concentration of ink (the number of inks n) are arranged in series in the sub-scanning direction (each recording head is composed of recording heads A and B). ), So that at least two or more ink dots formed for each pixel are ejected from the recording heads A and B by at least one dot or more, and the line feed positions of the recording heads A and B are different from each other. The control cancels and reduces streak-like unevenness (joint streaks) caused by problems such as the scanning accuracy of the print head.

For example, as a specific method of forming at least two and at most four ink dots for one pixel by using n kinds of inks and converting them into m-values, the following method is used.
A combination of selecting three inks (nC2 + nC1 ways) and a combination of selecting three inks from n kinds of inks (nC3 + n
C1 × n-1C1), a combination of selecting four inks from n types (nC4 + nC1 × n-1C2 + nC2), and a total of nC2 + nC1 + nC3 + nC1 × n-1C1 + nC4 + n without ink
This can be realized by selecting desired m combinations from C1 × n-1C2 + nC2 + 1.

In the first embodiment described below, the maximum number of ink dots for one pixel is described as four. However, the number is not limited to four and may be arbitrarily selected from 2 to 2n. it can. In addition, in the m combinations selected in this way, at least 2 except for “no ink”.
Since two inks are used, at least one of the two or more inks is distributed to each of the print heads A and B, and these print heads A and B are different from each other so that the line feed positions of the print heads A and B are different from each other. By controlling the arrangement of the lines, it is possible to reduce the connecting streaks. For this reason, the interval d between the two recording heads A and B is d = n × dcr ++ α (n: any positive number, α: 0 <α <dcr, where dcr is a predetermined width for conveying the recording medium. Any number).

In the present invention, a transmission image requiring a high density resolution will be described as an example. However, the present invention is not limited to a transmission image, and it is naturally applicable to a reflection image. . Next, the configuration of an inkjet recording apparatus that performs recording by the inkjet method according to the first embodiment of the present invention will be described with reference to FIGS.

The recording method by the ink jet method used in the present invention may be any of the conventionally known ink jet recording methods in which small ink droplets are ejected from nozzles using various driving principles to perform recording. Is also applicable. As a typical example, in a method described in Japanese Patent Application Laid-Open No. 54-59936, the ink subjected to the action of thermal energy causes a sudden change in volume, and the ink is ejected from the nozzle by the action force due to this state change. And an ink-jet method.

FIGS. 1 to 3 are views showing an example of the configuration of a head which is a main part of the ink jet recording apparatus according to the first embodiment of the present invention. The head 13 is formed by bonding a glass, ceramic or plastic plate having a groove 14 through which ink passes to a heating head 15 (a head is shown in the figure, but is not limited to this) used for thermal recording. Is obtained. The heating head 15 includes a protective film 16 made of silicon oxide or the like, and aluminum electrodes 17-1 and 17.
-2, a heating resistor layer 18 made of nichrome or the like, a heat storage layer 19, and a substrate 20 having good heat dissipation such as alumina.

The ink 21 has a discharge orifice (fine hole) 2
2, and the meniscus 23 is formed by the pressure P. Now, when an electric signal is applied to the electrodes 17-1 and 17-2, the area indicated by n of the heating head 15 generates heat rapidly, and bubbles are generated in the ink 21 in contact with the area. Protrudes, the ink 21 is discharged,
From the orifice 22, a recording droplet 24 is formed, and a recording medium 25 is formed.
Fly towards. FIG. 3 shows an external view of a multi-head (recording head) in which many heads shown in FIG. 1 are arranged. The multi-head (recording head) is manufactured by closely attaching a glass plate 13 having a plurality of grooves 14 and a heating head 15 similar to that described with reference to FIG.

FIG. 2 is a cross-sectional view of the head 13 along the ink flow path, in particular, a cross-sectional view taken along line AB in FIG. The configuration of the recording head used in the present invention is the same as the configuration of a recording head generally used in a conventional inkjet recording apparatus. Next, an example of an ink jet recording apparatus equipped with the above recording head will be described with reference to FIG.

FIG. 4 is a view showing an example of the ink jet recording apparatus according to the first embodiment of the present invention. In FIG.
Reference numeral 41 denotes a blade as a wiping member, one end of which is held by a blade holding member to become a fixed end, and takes the form of a cantilever. The blade 41 is disposed adjacent to the recording area by the recording head, and in the case of the present invention, is held in a form protruding into the movement path of the recording head. Reference numeral 42 denotes a cap, which is disposed at a home position adjacent to the blade 41, moves in a direction perpendicular to the moving direction of the recording head, and comes into contact with the ink ejection port surface,
A structure for performing capping is provided. Further, reference numeral 43 denotes an ink absorber provided adjacent to the blade 41, and is held in a form protruding into the movement path of the recording head, similarly to the blade 41. The blade 41, the cap 42, and the ink absorber 43 constitute an ink ejection recovery unit 44,
The blade 41 and the ink absorber 43 remove water, dust, and the like from the ink ejection port surface.

Reference numerals 31A and 31B denote recording heads which have ejection energy generating means and perform recording by discharging ink onto a recording medium opposed to an ink ejection port surface provided with ink ejection ports. Each of the recording heads 31A and 31B is composed of one multi-head group having multiple heads by the number of types of dark and light inks to be used. The recording heads 31A and 31B are slidably engaged with the guide shafts 32, respectively, and are connected (not shown) to a belt 34 driven by a motor 33. Thereby, the recording heads 31A and 31B can move along the respective guide shafts 32, and the recording heads 31A and 31B can move the recording area and the adjacent area. Each of the recording heads 31A and 31B is provided with a plurality of ink cartridge groups 38 for supplying a plurality of types of ink.

A paper feed unit 35 for inserting a recording medium is provided.
36 is a paper feed roller driven by a motor (not shown). With these configurations, the recording heads 31A, 31A
B, the recording medium is fed to a position facing each ink ejection port surface, and as the recording progresses, the discharge rollers 37
Is discharged to the paper discharge unit where. In the above configuration, when the recording heads 31A and 31B return to the home position at the end of recording or the like, the cap 42 of the ink discharge recovery unit 44 is retracted from the moving path of each of the recording heads 31A and 31B. Protruding inside. As a result, the ink ejection port surfaces of the recording heads 31A and 31B are wiped. When capping is performed while the cap 42 is in contact with the ink ejection port surfaces of the recording heads 31A and 31B, the cap 42 moves so as to protrude into the movement path of the recording heads 31A and 31B.

When the recording heads 31A and 31B move from the home position to the recording start position, the cap 42 and the blade 41 are at the same positions as the positions at the time of wiping described above. As a result, even in this movement, the ink ejection port surfaces of the recording heads 31A and 31B are wiped.
The above-described movement of the recording heads 31A and 31B to the home position is performed not only at the end of recording or at the time of ink ejection recovery, but also at predetermined intervals while the recording heads 31A and 31B move through the recording area for recording. To the home position adjacent to the wiping, and the wiping is performed in accordance with this movement.

In the present invention, the recording heads 31A, 31
In each of B, the multi-head group is arranged in series in the sub-scanning direction. Further, the two recording heads 31A and 31B do not need to be completely synchronized, and the recording may be performed while the recording medium is conveyed intermittently. In the case of color conversion, a multi-head group containing black, cyan, magenta, and yellow dark and light inks is arranged in four colors. Further, the ink may be three colors of cyan, magenta and yellow instead of four colors.

Next, a control configuration for executing the printing control of the above-described ink jet printing apparatus will be described with reference to FIG. FIG. 5 is a block diagram illustrating a control circuit of the inkjet recording apparatus according to the first embodiment of the present invention. 5, reference numeral 1700 denotes an interface for inputting a recording signal from the data transmission path 210, 1701 denotes an MPU, 17
Reference numeral 02 denotes a ROM for storing a printer control program executed by the MPU 1701, and reference numeral 1703 denotes a DRAM for storing various data (such as the print signal and print data supplied to the print heads 31A and 31B). A gate array (GA) 1704 controls supply of print data to the print heads 31A and 31B, and also controls data transfer between the interface 1700, the MPU 1701, and the RAM 1703. With the above configuration, a controller unit 1720 for controlling the device is configured.

Reference numeral 1710A denotes a carrier motor for conveying the recording head A, 1710B denotes a carrier motor for conveying the recording head B, and 1709 denotes a conveyance motor for conveying the recording medium. 1705A is the recording head 31A
1705B is a recording driver for driving the recording head 3.
1B is a head driver for driving 1B. 1706, 17
Reference numerals 07A and 1707B denote motor drivers for driving the transport motor 1709, the carrier motor 1710A, and the carrier motor 1710B, respectively. Reference numeral 1711 denotes an operation panel provided with keys for performing various setting instructions and registration instructions, an LCD for displaying messages, an LED lamp for displaying the status of the apparatus, and the like.

The operation of the control circuit will be described. For example, when a recording signal enters the interface 1700 from the host computer via the data transmission line 210, the recording signal is converted into recording data for printing between the gate array 1704 and the MPU 1701. Is converted. Then, the motor drivers 1706, 1707A, and 1707B are driven, and the recording heads 31A and 31B are driven according to the recording data sent to the head drivers 1705A and 1705B, thereby performing a recording operation.

The MPU 1701 is connected to the interface 17
The communication processing with the host computer can be performed via the 00 and the host computer can be notified of memory information and resource data related to the DRAM 1703 and host computer record information in the ROM 1702. In addition, the ink tanks that supply ink to the recording heads 31A and 31B run out of ink, and the recording heads 31A and 31B.
1B, even when an abnormality occurs in the motor or the like, these events can be notified to the host computer.

The following is an example of a case in which a medical X-ray transmission image of 256 gray levels is output using six types of black and dark inks and discharging two to four ink dots for one pixel. Will be explained. First, a functional configuration of recording control in the inkjet recording apparatus according to the first embodiment will be described with reference to FIG.

FIG. 6 is a block diagram showing a functional configuration of recording control in the ink jet recording apparatus according to the first embodiment of the present invention. In the first embodiment, the functional configuration described below is realized by the processing of the MPU 1701. However, dedicated hardware may be provided in the controller 1720. Alternatively, the host computer may execute processing as shown in FIG. 9 to generate multi-valued data, and transmit this to the inkjet recording apparatus.

In FIG. 6, reference numeral 1 denotes an ink density data / combination data portion, which is a combination data indicating a combination of ink types (for example, six types in the first embodiment) used in the recording heads 31A and 31B, and Are stored. Note that the ink density data / combination data section 1 is formed in the DRAM 1703. Reference numeral 2 denotes a multi-level error diffusion processing unit that performs multi-level error diffusion processing on input image data (256 gradations) based on the ink density data stored in the ink density data / combination data unit 1. In the first embodiment, a case where input image data is converted into 49 values will be described as an example. However, a desired multi-level error diffusion process can be performed according to the number of gradations that can be expressed by the inkjet recording apparatus. The details of the multi-level error diffusion process will be described later with reference to the flowchart of FIG.

Reference numeral 3 denotes a data distribution unit which generates ink ejection control data indicating the type of ink to be distributed to the recording heads 31A and 31B based on the result of the multi-level error diffusion processing unit 2. A recording head / paper feed control unit 4 controls the driving of the recording heads 31A and 31B and the conveyance of the recording medium based on the ink ejection control data generated by the data distribution unit.

Here, the recording head 31A of the first embodiment,
Table 1 below shows the inks used for 31B.
As shown in Table 1, six types of inks are used,
A, b, c, d, e, and f in order from the highest density.
At the same time, the dye concentration (%) and the transmission density (OD) of each of the inks a to f are shown. Each ink is composed of a dye and a solvent, and the solvent contains various additives such as a surfactant and a humectant. These additives control the ejection characteristics from the recording head and the absorption characteristics on the recording medium.

[0046]

[Table 1] If these inks are used and the type of ink to be applied to the same pixel is up to four, then 6C2 + 6C1 + 6C3 + 6C1 ×
There are 162 combinations of 6-1C1 + 6C4 + 6C1.times.6-1C2 + 1 = 162. Considering overlapping densities among them, the number of gradations that can be represented by one pixel is 100. In the first embodiment, four of these gradation numbers are used.
An image is output using nine gradations. That is, as described above, the input image data (256 gradations) is converted into a 49-value image and an image is output. FIG. 7 shows the types and combinations of inks for expressing each gradation (49 gradations) at that time. In the figure, the column of No. indicates each gradation. In the columns of the inks a to f, A indicates that the ink is ejected from the recording head 31A, and B indicates that the ink is ejected from the recording head 31B. In addition, x indicates that the ink is not ejected. Dye amount, number of layers, O.D.
D. Columns indicate the amount of dye expressing each gradation, the number of ink dots to be superimposed on one pixel, and the O.D. D. Is shown. Also, dl
The column of [i] (i = 0 to 48: integer) indicates the ink density level expressing each gradation. Also, th [i] (i
= 1 to 48: integer) indicates a threshold value for determining the input image data to any one of 49 tones.
Note that the threshold is usually determined as an ink density level at a middle point between the ink density levels dl [k-1] and dl [k].

Here, a combination of ink types indicating each gradation is combination data, and an ink density level determined based on the combination data is ink density data. Subsequently, the dye amount of the ink discharged onto the recording medium and the O.D. D. FIG. 8 shows the relationship with (transmission density). As shown in FIG. 8, as the amount of dye increases, the amount of dye and O.D. D. (Transmission density) is no longer proportional. Therefore, in the first embodiment, the above-described ink density level dl [i] is considered in the high-density portion in consideration of human visual characteristics in the high-density portion (the density resolution decreases from around OD> 2).
Is set to be wider.

In the first embodiment, multi-valued data is obtained by using the 49-value ink density levels (dl [0] to dl [48]) and the 48-value threshold values (th [1] to th [48]). The error diffusion processor 2 converts the input image data (256 gradations) into 49
A multi-valued error diffusion process for converting into a value is performed. As described above, in the multi-level error diffusion processing according to the first embodiment, there are a plurality of thresholds for multi-leveling the input image data, here 48 levels, and this point is significantly different from the normal error diffusion processing. In the first embodiment, the input image data is multi-valued by using the multi-value error diffusion process. However, the present invention is not limited to this. For example, the input image data may be multi-valued using another multi-value conversion method such as a multi-value average density storage method, a multi-value dither matrix method, or a sub-matrix method.

Next, the procedure of the recording control of the ink jet recording apparatus of the first embodiment will be described with reference to the flowchart of FIG. FIG. 9 is a flowchart illustrating a procedure of recording control of the inkjet recording apparatus according to the first embodiment of the present invention. First, in step S1, data relating to ink used in the recording heads 31A and 31B including ink density data and combination data is stored in the ink density data / combination data unit 1.

Next, in step S2, input image data is input, and multi-level error diffusion processing is performed for each pixel indicated by the input image data. Here, details of the multi-level error diffusion processing will be described with reference to FIG. FIG. 10 is a schematic diagram showing the arrangement of input image data and 49-valued image data obtained after multi-value error diffusion processing according to the first embodiment of the present invention. That is, 256 pixels for each pixel indicated by the input image data
It is a figure which shows a part of arrangement | positioning of the pixel in density data (0 {black} -255 {transparent}).

In FIG. 10A, f (i, j) has a 256 density data level of the target pixel (i, j) to be multi-valued (49-valued). The pixels f (i−2, j−1) to (i−1, j) above the broken line have already been subjected to the multi-level (49-level) processing, and B (i, j)
Are the density data (“0”, “18.1”,..., “251.8”,
49 values of "255"). Also,
After the target pixel (i, j) is multi-valued (49-valued), f
(I, j + 1), f (i, j + 2),...

First, the 256 density data level f (i, j) of the pixel of interest (i, j) is compared with a threshold value th [k]. th [k] ≦ f (i, j) <th [k + 1] (1) B (i, j) = dl [k] (2) Then, k that satisfies the above equation (1) is obtained, and (2) ), The density data B (i, j) of the target pixel (i, j) after multi-level conversion (49-level conversion) is determined.

Subsequently, using the error diffusion matrix shown in FIG. 10B, the density data B (i, j) determined by the above-mentioned multi-value processing and the 256 density data level before the multi-value processing are obtained. An error err generated between f (i, j) is calculated by the following equation (3). err = f (i, j) -dl [k] (3) Then, the calculated error err is diffused to other pixels according to the following equation (4).

F ′ (x, y) = f (x, y) + err × M (xi, y−j) ÷ 31 (4) As described above, the error err is calculated as shown in FIG. In accordance with the distribution of the error diffusion matrix as shown in the figure, the value is diffused to each pixel, and thereafter, the value f '(i, i,
Similarly, a multi-level (49-level) process is performed using j).

In step S3, in the data distribution unit 3, based on the above-mentioned combination data shown in FIG. 7 corresponding to the density data B (i, j) obtained by the multi-level (49-level) processing. Recording head 31A, 31B
Is generated. For example, when the density data B (i, j) is 111.7, the ink ejection is performed such that the ink b is ejected from the recording heads 31A and 31B, the ink e is ejected from the recording head 31B, and the ink f is ejected from the recording head 31A. Generate control data.

In step S4, the recording head / paper feed control unit 4 controls the driving of the recording heads 31A and 31B and the conveyance of the recording medium in accordance with the ink ejection control data to form a gradation image.
In the first embodiment, a combination of six ink jet heads equivalent to 360 dpi (64-nozzle multi-head, 40 ng of ink ejection amount per dot) is used as the recording heads 31A and 31B, respectively, and the medical gradation image ( Output). Further, each recording head 31
A and 31B are printed by two-pass printing, and the distance d between the two print heads 31A and 31B in the sub-scanning direction is set.
= N × dcr + α, α = (64 nozzle width / 2)
/ 2.

Under the above conditions, the recording head 31
A specific control example of the driving of A and 31B and the conveyance of the recording medium will be described. First, the recording medium is conveyed to the recording start position of the recording head 31A. Then, two-pass printing is performed by the print head 31A using the ink ejection control data corresponding to the print head 31A until the print medium reaches the print start position of the print head 31B. That is, the print head 31B is on standby until the print medium reaches the print start position of the print head 31B, and the ink discharge control data corresponding to the print head 31B during the standby is recorded on the print head 31B. It is delayed until the recording medium reaches the start position. When the recording medium reaches the recording start position of the recording head 31B, the recording heads 31A, 31B
The ink ejection control data corresponding to
1A and 31B, and two-pass printing is performed by each of the print heads 31A and 31B. As described above, by controlling the supply of the ink ejection control data corresponding to each of the print heads 31A and 31B, two-pass printing by the print heads 31A and 31B having a characteristic configuration of the present invention is realized.

As described above, according to the first embodiment, the two recording heads 31A and 31B capable of discharging a plurality of types of dark and light inks in the recording medium transport direction (sub-scanning direction).
When an image is formed, at least one ink dot forming a pixel is formed from each of the recording heads 31A and 31B.
By discharging one or more lines and making the line feed positions of the recording heads 31A and 31B different from each other, it is possible to offset and reduce the streak-like unevenness that occurs in the recorded image due to problems such as the conveyance accuracy of the recording medium.

Further, in order to increase the number of gradations of an image to be recorded, for example, without newly creating a recording head capable of ejecting many types of ink to one recording head,
It is possible to increase the number of gradations of an image to be recorded simply by mounting two recording heads similar to the conventional recording head in the ink jet recording apparatus in the above-described configuration. That is, it is possible to obtain a good gradation image with many gradations without at least adding a large cost for creating a new recording head. [Second Embodiment] In the second embodiment, a medical X-ray transmission image of 4096 black and white gradations is formed using 6 types of black and dark inks in the same manner as in the first embodiment, and two to six black and white inks are used for one pixel. An example in which ink dots are ejected and output will be described. The inks used in the recording heads 31A and 31B according to the second embodiment are shown in Table 2 below.

[0060]

[Table 2] If these inks are used and the type of ink to be applied to the same pixel is up to six, then 6C2 + 6C1 + 6C3 + 6C1 ×
6-1C1 + 6C4 + 6C1 × 6-1C2 + 6C2 + 6C5 + 6C1 × 6-1
C3 + 6C2 × 6-2C1 + 6C6 + 6C1 × 6-1C4 + 6C2 × 6-2C
There are 429 combinations of 2 + 6C3 + 1 = 429. Among them, the number of gradations that can be represented by one pixel is 321
Becomes In the second embodiment, an image is output using 134 gradations among these gradation numbers. That is, the input image data (256 gradations) is converted into 134 values and an image is output. FIGS. 11 to 13 show the types and combinations of inks for expressing each gradation (134 gradations) at that time.
Each column in the figure is the same as that in FIG. 7, and the description is omitted here.

Under the above conditions, FIG.
The image is output in the same procedure as the flowchart shown in FIG. The recording procedure in the second embodiment is the same as the recording procedure except that multi-level error diffusion processing for converting input image data into 134 values is performed.
Since it is the same as the first embodiment, the details are omitted.
In the second embodiment, as in the first embodiment, 360 dp
A combination of six i-type inkjet heads (64-nozzle multi-head, discharge amount per dot 40 ng) was used as recording heads 31A and 31B, respectively, and a medical gradation image (transmission) was output. In addition, printing is performed by four-pass printing, and two print heads 31A and 31B are used.
Is set to α = (64 nozzle width / 4) / 2 at an interval d = n × dcr + α in the sub-scanning direction.

As described above, according to the second embodiment, the two recording heads 31A and 31B capable of ejecting a plurality of types of dark and light inks in the recording medium conveyance direction (sub-scanning direction).
When an image is formed, at least one ink dot forming a pixel is formed from each of the recording heads 31A and 31B.
By discharging one or more lines and making the line feed positions of the recording heads 31A and 31B different from each other, it is possible to offset and reduce the streak-like unevenness that occurs in the recorded image due to problems such as the conveyance accuracy of the recording medium.

Further, in order to increase the number of gradations of an image to be recorded, for example, a new recording head capable of ejecting many kinds of inks to one recording head can be prepared without newly forming the recording head.
It is possible to increase the number of gradations of an image to be recorded simply by mounting two recording heads similar to the conventional recording head in the ink jet recording apparatus in the above-described configuration. That is, it is possible to obtain a good gradation image with many gradations without at least adding a large cost for creating a new recording head.

Next, a feature of the present invention is that "two recording heads capable of discharging a plurality of types of dark and light inks in the recording medium transport direction (sub-scanning direction) are provided, and when forming an image,
In order to clarify the effect obtained by the configuration in which at least one or more ink dots forming pixels are ejected from each recording head and the line feed positions of each recording head are different from each other, the following comparative example will be described. Comparative Example 1 An image was formed using one recording head capable of using six types of dark and light inks in the same manner as in Embodiment 1.
In this case, only one ink is applied to one pixel, that is, using (6 + 1) gradations per pixel,
Multi-level error diffusion processing was performed, and a medical X-ray transmission image of 256 gray scales was output.

In this case, compared to the first embodiment, the dots were more conspicuous, and stripe-like unevenness occurred at the line feed position of the recording head. Comparative Example 2 An image was formed by using two recording heads capable of using six types of dark and light inks as in the first embodiment, and forming a new line at the same line feed position of each recording head (d = 2).
× dcr). In this case, an image having 49 gradations per pixel can be output with six types of dark and light inks as in the first embodiment, but a stripe-shaped unevenness occurs at the line feed position of the recording head as compared with the first embodiment. .

As described above, as shown in Comparative Examples 1 and 2 with respect to Embodiments 1 and 2, the present invention can discharge a plurality of types of dark and light inks in the recording medium conveyance direction (sub-scanning direction).
When one print head is provided and an image is formed, at least one ink dot forming a pixel is formed from each print head.
By discharging one or more lines and making the line feed positions of the recording heads different from each other, it is possible to offset and reduce streak-like unevenness that occurs in a recorded image due to problems such as accuracy in transporting a recording medium.

Further, in order to increase the number of gradations of an image to be recorded, for example, a new recording head capable of ejecting many kinds of inks to one recording head can be prepared without using a new recording head.
It is possible to increase the number of gradations of an image to be recorded simply by mounting two recording heads similar to the conventional recording head in the ink jet recording apparatus in the above-described configuration. That is, it is possible to obtain a good gradation image with many gradations without at least adding a large cost for creating a new recording head.

The present embodiment is particularly provided with a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for performing ink ejection even in an ink jet recording system. By using a method that causes the state of ink to change due to energy,
Higher recording density and higher definition can be achieved. For the representative configuration and principle, see, for example, US Pat.
It is preferable to use the basic principle disclosed in Japanese Patent No. 29,4740796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). Applying at least one drive signal corresponding to the recording information and providing a rapid temperature rise exceeding film boiling to the electrothermal transducer, thereby causing the electrothermal transducer to generate thermal energy, and This is effective because it causes film boiling on the heat-acting surface, and as a result, bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis can be formed. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When this drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are immediately and appropriately performed, and therefore, the ejection of liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed. As a configuration of the recording head, in addition to the combination of the ejection port, the liquid path, and the electrothermal converter (a linear liquid flow path or a right-angled liquid flow path) as disclosed in the above-mentioned respective specifications, a heat acting surface A configuration using U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose a configuration in which a is bent, is also included in the present invention. In addition, Japanese Patent Laid-Open Publication No. Sho 5 discloses a configuration in which a common slot is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters.
Japanese Unexamined Patent Publication No. 9-123670 discloses a structure in which an opening for absorbing a pressure wave of thermal energy corresponds to a discharge portion.
A configuration based on JP-A-9-138461 may be adopted.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is determined by combining a plurality of recording heads as disclosed in the above-mentioned specification. This may be either a configuration satisfying the above requirements or a configuration as a single recording head formed integrally. In addition, a replaceable chip-type recording head that can be electrically connected to the device main body and supplied with ink from the device main body by being attached to the device main body, or ink that is integrated with the recording head itself A cartridge type recording head provided with a tank may be used.

In order to further stabilize the recording operation of the recording head, it is preferable to add a preliminary auxiliary means or the like provided as a configuration of the recording apparatus of the present embodiment. Specific examples thereof include a means for pressurizing or suctioning the recording head, a preheating means using an electrothermal converter, a separate heating element or a combination thereof. It is also effective to provide a preliminary ejection mode in which ejection is performed separately from printing, in order to perform stable printing.

Further, the recording mode of the recording apparatus is not limited to a recording mode of only a mainstream color such as black, but may be a recording head integrally formed or a combination of a plurality of recording heads. Alternatively, the apparatus may be provided with at least one of full colors by color mixture. As described above, the present embodiment has been described on the assumption that the ink is a liquid. However, even if the ink solidifies at room temperature or lower, an ink that softens or liquefies at room temperature is used. Or, in the inkjet method, generally, the temperature of the ink itself is adjusted within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. It is sufficient that the ink is in a liquid state when the use recording signal is applied.

In addition, in order to positively prevent the temperature rise due to thermal energy by using the energy of the state change of the ink from the solid state to the liquid state, or to prevent the ink from evaporating, the ink is solidified in a standing state. Alternatively, ink that liquefies by heating may be used. In any case, the application of heat energy causes the ink to be liquefied by application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start to solidify when reaching the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used. In such a case, as described in JP-A-54-56847 or JP-A-60-71260, the ink is held as a liquid or solid in a concave portion or through hole of a porous sheet, It is good also as a form which opposes an electrothermal transducer. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition to the above, the recording apparatus according to the present invention may be provided not only as an image output terminal of an information processing apparatus such as a computer but also integrally or separately, a copying apparatus combined with a reader or the like, and a transmission / reception apparatus. It may take the form of a facsimile machine having functions.
Note that the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but a device including one device (for example, a copying machine, a facsimile machine, etc.). May be applied.

Further, an object of the present invention is to supply a storage medium storing program codes of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk,
A CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written to a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the program code is read based on the instruction of the program code. It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

[0079]

As described above, according to the present invention,
It is possible to provide a recording apparatus capable of reducing streak-like unevenness and recording a good gradation image without significantly increasing the cost, and a control method of the apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a head that is a main part of an inkjet recording apparatus according to a first embodiment of the invention.

FIG. 2 is a diagram illustrating a configuration example of a head that is a main part of the inkjet recording apparatus according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration example of a head that is a main part of the inkjet recording apparatus according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of the inkjet recording apparatus according to the first embodiment of the present invention.

FIG. 5 is a block diagram illustrating a control circuit of the inkjet recording apparatus according to the first embodiment of the present invention.

FIG. 6 is a block diagram illustrating a functional configuration of recording control in the inkjet recording apparatus according to the first embodiment of the present invention.

FIG. 7 shows ink density data according to the first embodiment of the present invention;
FIG. 6 is a diagram illustrating data regarding ink including combination data.

FIG. 8 shows the relationship between the dye amount of the ink ejected onto the recording medium according to the present invention and the O.D. D. FIG. 4 is a diagram showing a relationship with (transmission density).

FIG. 9 is a flowchart illustrating a procedure of recording control of the inkjet recording apparatus according to the first embodiment of the present invention.

FIG. 10 is a schematic diagram illustrating an arrangement of input image data and 49-valued image data obtained after multi-value error diffusion processing according to the first embodiment of the present invention.

FIG. 11 is a diagram showing ink data including ink density data and combination data according to a second embodiment of the present invention.

FIG. 12 is a diagram illustrating data relating to ink including ink density data and combination data according to a second embodiment of the present invention.

FIG. 13 is a diagram illustrating ink-related data including ink density data and combination data according to the second embodiment of the present invention.

FIG. 14 is a diagram showing a conventional density distribution table.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink density data / combination data part 2 Multi-level error diffusion processing part 3 Data distribution part 4 Recording head / paper feed control part 13 Head 14 Groove 15 Heating head 16 Protective film 17 Electrode 18 Heating resistance layer 19 Heat storage layer 20 Heat dissipation substrate DESCRIPTION OF SYMBOLS 21 Ink 22 Orifice 23 Meniscus 24 Recording droplet 25 Recording medium 31A, 31B Recording head 32 Guide shaft 33 Carriage drive motor 34 Drive belt 35 Paper feed unit 36 Paper feed motor 37 Discharge roller 38 Ink cartridge 41 Blade 42 Cap 43 Ink absorption Body 44 Discharge recovery part

Continued on the front page (72) Inventor Akihiro Mohri 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Osamu Kame 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) The inventor, Takeo Eguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) The inventor, Retsu Shibata 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (14)

[Claims] 1. A recording apparatus for recording an image on a recording medium based on input image data, comprising: conveying means for conveying the recording medium by a predetermined feed width; A first printing unit that scans and prints a printing area of a predetermined width, and is installed at a position apart from the position where the first printing unit is installed by a predetermined distance that is not an integral multiple of the predetermined feeding width in the transport direction, A second recording unit that scans and records in a direction perpendicular to the transport direction of the recording medium; and performs transport by the transport unit and recording by the first recording unit and the second recording unit based on the input image data. A recording device comprising: a control unit for controlling the recording device. 2. The recording apparatus according to claim 1, wherein the first recording unit and the second recording unit are ink jet recording heads that perform recording by discharging ink. 3. The recording head according to claim 1, wherein the first recording unit and the second recording unit are a recording head that discharges ink by using thermal energy, and include a thermal energy converter that gives the ink. The recording device according to claim 1. 4. A recording apparatus for recording a gradation image on a recording medium based on input image data, comprising: conveying means for conveying the recording medium by a predetermined feed width; A first recording unit that has a plurality of recording agents and scans a recording area having a predetermined width by scanning in a direction perpendicular to the transport direction of the recording medium; and transporting the recording medium from a position where the first recording unit is installed. It has a plurality of printing agents having different densities of two or more types of similar colors in a direction that is not an integral multiple of the predetermined feed width in the direction, and performs printing by scanning in a direction perpendicular to the transport direction of the printing medium. A second recording unit, and a recording agent used for recording a pixel of a gradation image to be recorded on the recording medium, wherein at least one recording agent included in each of the first recording unit and the second recording unit is based on the pixel. Decision to determine combination Means, and control means for controlling conveyance by the conveyance means and recording by the first recording means and the second recording means based on the input image data and the recording material determined by the determination means. Characteristic recording device. 5. The determining means relates to a density level that can be expressed by combining one or more recording materials included in each of the first recording means and the second recording means, and a combination of a recording agent that expresses the density level. A storage unit for storing information; and a multi-level conversion unit for converting the input image data to multi-level based on a density level stored in the storage unit. 5. A recording material to be used for recording is determined by acquiring from the storage device a combination of recording materials expressing the density levels of pixels of the input image data multivalued by the multivaluer. The recording device according to claim 1. 6. The recording apparatus according to claim 4, wherein the first recording unit and the second recording unit are ink jet recording heads that perform recording by discharging ink. 7. A recording head for ejecting ink using thermal energy, wherein the first recording means and the second recording means include a thermal energy converter for applying ink. The recording device according to claim 4. 8. A method for controlling a recording apparatus for recording an image on a recording medium based on input image data, comprising: a transporting step of transporting the recording medium by a predetermined feed width; First scanning in various directions
A first recording step of recording a recording area of a predetermined width by a recording unit; and a first recording unit which is disposed at a position apart from a position where the first recording unit is disposed by a predetermined distance that is not an integral multiple of the predetermined feed width in the transport direction; A second recording step of recording by a second recording unit that scans in a direction perpendicular to the transport direction of the recording medium. 9. The method according to claim 8, wherein the first recording unit and the second recording unit are ink jet recording heads that perform recording by discharging ink. 10. The recording head according to claim 1, wherein the first recording unit and the second recording unit are a recording head that discharges ink using thermal energy, and includes a thermal energy converter that applies the ink to the recording head. A method for controlling a recording apparatus according to claim 8. 11. A method for controlling a printing apparatus for printing a gradation image on a printing medium based on input image data, comprising: a conveying step of conveying the printing medium by a predetermined feed width; A first recording step of recording a recording area having a predetermined width by a first recording unit having a plurality of recording materials having different densities and scanning in a direction perpendicular to the conveying direction of the recording medium; It is installed at a position that is not an integral multiple of the predetermined feed width in the conveyance direction from the installation position, and has a plurality of recording agents having different densities of two or more types of similar colors, and is perpendicular to the conveyance direction of the recording medium. A second printing step of printing by a second printing unit that scans in the direction, and a printing agent used for printing pixels of a gradation image to be printed on the printing medium, based on the pixels, the first printing unit and the second printing unit. Recording means Control method for a recording apparatus, characterized in that it comprises a determination step of determining one or more combinations of recording agents respectively have. 12. The determining step relates to a density level that can be expressed by combining one or more recording agents included in each of the first recording unit and the second recording unit, and a combination of a recording agent that expresses the density level. A storage step of storing information in a storage medium; and a multi-level conversion step of multi-level input image data based on a density level stored in the storage medium in the storage step. The recording medium used for recording the pixels of the gradation image is a combination of the recording medium expressing the density level of the pixel of the input image data multi-valued in the multi-value conversion step from the storage medium stored in the storage step. The method of controlling a recording apparatus according to claim 11, wherein the method is obtained and determined. 13. The method according to claim 11, wherein the first recording unit and the second recording unit are ink jet recording heads that perform recording by discharging ink. 14. The recording apparatus according to claim 1, wherein the first recording unit and the second recording unit are recording heads that discharge ink by using thermal energy, and include a thermal energy converter that applies the ink to the recording head. A method for controlling a recording apparatus according to claim 11.