JP3387764B2 - Ink jet recording apparatus and ink jet recording method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording apparatus and an inkjet recording method, and more particularly to an inkjet recording apparatus and an inkjet recording method for performing gradation recording using inks having different densities.

[0002]

2. Description of the Related Art Conventionally, as a recording method in a facsimile machine, a digital copying machine, a digital printer, etc.,
An electrophotographic method, a sublimation transfer method, a thermal transfer method, an inkjet recording method, and the like are known. As the gradation recording method by these methods, the dot diameter or dot density by toner, ink, dye or the like attached to the recording medium is modulated by changing the voltage applied to the recording element or the pulse width. There is known a method, or a method of modulating the number of dots formed in a unit area of a recording medium while keeping the dot diameter or the dot density constant. Furthermore, a gradation recording method is also known which is a combination of the dot diameter or dot density modulation method and the dot number modulation method described above.

Among the above-mentioned recording methods, the ink jet recording method, which has a relatively simple device structure and ejects ink on demand for recording, has been rapidly prevailing in recent years.

In this type of recording apparatus, a so-called multi-nozzle head is generally used, which is composed of an ejection port array in which a plurality of ink ejection ports are integrated and arranged in order to improve the recording speed. Further, as a device compatible with color recording, a device provided with the above-described recording head for each color of ink used is known.

When gradation recording is performed in such an ink jet recording apparatus, pseudo halftone processing is mainly performed because it is relatively difficult to modulate the diameter of dots formed on a recording medium. By doing so, gradation was performed. However, according to the dot number modulation method based on the pseudo halftone processing, it is generally known that there is a problem that it is difficult to achieve both high gradation and high resolution. Further, when the dot diameter is relatively large, the graininess of the recorded image may be a problem. To solve the above problems, one of the solutions is to make the dot diameter smaller, but this method involves technical difficulties in the structure and manufacturing of the head, and increases the cost. There is an evil.

On the other hand, there has been proposed a method of performing gradation recording using inks of similar colors but different densities (hereinafter, also referred to as dark and light inks). In this method, for example, the light area to the intermediate density area of the image are recorded with low density ink, the intermediate density area is recorded using both low density ink and high density ink, and further from the intermediate density area. The dark portion is for recording with high density ink, which reduces the above-mentioned graininess and enables recording of a good image with high gradation.

In this recording method using the dark and light inks, data is generated as to which of a plurality of inks having different densities is to be used. For example, when the inks of four kinds of densities are used, the input image data is used. The output image data is obtained as the density signal level for each ink by referring to the distribution table having the characteristics shown in FIG. 1 according to the density signal level. Then, the image data obtained in this manner is subjected to binarization processing, and based on the result, ink is ejected by the corresponding recording heads of the respective inks to record a gradation image. It is possible.

[0008]

However, according to the above-mentioned conventional method, for example, when the recording medium used for recording is changed and the recording medium has different ink recording characteristics from those used up to then. Need to perform the above-mentioned processing according to the recording medium. For example, when a transparent recording medium having a receiving layer provided on a transparent substrate, for example, a film of polyethylene terephthalate is used after using a reflective medium such as plain paper as a recording medium, the transparent recording medium is It is necessary to prepare a corresponding sorting table and perform image processing such as changing the gamma characteristic corresponding to the transparent recording medium. Further, when it is desired to perform gamma correction on the gradation of a recorded image, the image processing has to be performed for each recording medium.

On the other hand, the weight of this problem depends to a large extent on the pseudo halftone processing using the distribution table. This will be described below.

As image data for gradation recording,
For example, when using 8-bit digital image data,
The bit value indicating the density signal of each pixel is represented by a value from 0 to 255, and the brightest digital value of the image is represented by 255 and the darkest digital value thereof is represented by 0. In the above description, 0 is replaced by a bright part and 255 is replaced by a dark part for convenience of description.

When printing is performed using four kinds of inks having different densities, the gradation image data is output image data according to the distribution table shown in FIG. obtain. In order of increasing ink density, A-2, A-3, and A-4, respectively.
According to the line, the image data corresponding to each ink is obtained. These image data are further analyzed by the systematic dither method,
Binary data is obtained by the binarization process using the error diffusion method,
Based on this, recording is performed by driving the recording heads of the corresponding inks.

Here, it is preferable that the value of the apex of the line showing the distribution table shown in FIG. 1 is determined by the optical density of the dark and light ink on the recording medium.

For example, the bit value of the apex of line A-1 is 64 here, and similarly, line A-2, line A-3, line A
The vertices of the -4 line are 128, 192, and 255, respectively, and this value is obtained when the optical densities of the four types of dark and light inks used on the recording medium are 1: 2: 3: 4. Corresponding to each other, the ratio of this bit value and the bit value is set to be substantially equal. This is because if the ratio of the reflection optical density of each ink and the ratio of bit values when recording on a recording medium using four types of ink having different densities as shown in the example are equal, This is because the linearity of the key is exhibited well. The ratio of the optical density of the dark and light inks and the ratio of the bit value at each apex of the line indicating the distribution table do not necessarily have to be the same when the gradation is adjusted non-linearly. In order to achieve good reproducibility, it is desirable that the density conversion characteristics in the density distribution table and the like have linearity.

However, as described above, when the recording medium is changed, for example, when recording on plain paper,
The reflection optical density of each dark and light ink changes when recorded on special paper such as glossy paper. Furthermore, in the case of a transmissive medium, there is a difference between reflected light and transmitted light in the state of actually observing an image, and the gradation property of a recorded image varies as the recording medium changes.

On the other hand, in order to prevent such a change in gradation, it is conceivable to carry out processing with a sorting table according to the recording medium used. However, for example, when the recording medium is changed in the middle of recording, the process relating to the change of the distribution table must be performed accordingly, resulting in a decrease in the recording speed as a whole,
In addition, preparing a plurality of tables causes a problem of cost increase. Also, when performing gamma correction when outputting a gradation image, it is necessary to perform arithmetic processing according to the changed recording medium, and similarly, time is spent on arithmetic processing, resulting in increased cost and wasted time. It will be.

Further, when the transmissive medium is used for gradation recording according to the recording characteristics of the reflective medium when the recording medium is changed, particularly when the reflective medium and the transmissive medium are mutually changed, the gradation reproducibility is remarkably inappropriate. In addition, the maximum density is lowered. This phenomenon is regarded as a problem especially when observing on a Schaukasten used for medical diagnosis.

The present invention has been made in order to solve the above-mentioned problems, and the purpose thereof is to change the combination of inks used for recording even if the image data obtained by the image processing remains unchanged. Accordingly, it is an object of the present invention to provide an inkjet recording apparatus and an inkjet recording method capable of outputting a gradation image adapted to the recording characteristics of the recording medium even if the recording medium is changed.

[0018]

Therefore, according to the present invention,
An inkjet recording apparatus for performing recording using a plurality of inkjet heads capable of ejecting inks of similar colors having mutually different densities, wherein a plurality of inkjet heads are selected from the plurality of inkjet heads according to a recording medium used for recording. Selection means for selecting a head, and a control means for performing gradation recording on the recording medium based on ejection data corresponding to a plurality of inks used for recording, using a plurality of inkjet heads selected by the selection means It is characterized by including ,.

Further, there is provided an ink jet recording method for performing recording by using a plurality of ink jet heads capable of ejecting inks of similar colors having different densities, the same colors having different densities depending on a recording medium used for recording. A plurality of inks are selected and the selected plurality of inks are ejected from the plurality of ink jet heads to perform gradation recording.

According to the above construction, a plurality of ink sets used for recording are selected according to the recording medium used for recording, and thus the selected ink is used correspondingly. The optical density realized on the recording medium can be determined so as to have a predetermined linear relationship with the recording data, whereby the recording medium to be used is changed without adding any processing to the recording data. Even in this case, it is possible to always record an image with good gradation.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

The present invention basically prepares a plurality of groups of dark and light inks to be associated with each other as a result of the dark and light distribution processing, so that even if the recording medium is changed, the dark and light inks are dealt with in the distribution processing. The ratio of the predetermined input image data values and the ratio of the optical densities realized on the recording medium by the respective corresponding inks based on the input image data are made equal, whereby the gradation of the recorded image is always maintained. It guarantees linearity.

However, in another embodiment of the present invention, the combination of the dark and light inks is determined in consideration of the additivity of the density when the inks are overlaid and ejected on the recording medium.

For example, in a transmissive recording medium, density additivity due to multi-strike of dark and light ink is relatively good in the entire range of density gradation. On the other hand, the reflective recording medium becomes more difficult to achieve as the density additivity due to the multiple printing of dark and light ink becomes higher. This becomes remarkable especially when the coloring agent of the ink used for recording contains a dye as a main component.

That is, when the dark and light inks are multiply printed, the optical density realized by the dots formed by this multiple printing is preferably the sum obtained by simply adding the optical densities of the respective inks. However, as described above, particularly when a reflective recording medium is used, or when the main component of the colorant of the ink is a dye, the sum is not simply added, and the optical density is lower. Often becomes. This is said that additivity is not established.

Therefore, in another embodiment of the present invention, the density of the dark and light ink to be prepared has the following relationship.

With respect to the inks having the maximum densities of the dark and light ink groups defined corresponding to the transmissive recording medium and the dark and light ink groups defined corresponding to the reflective recording medium,

[0028]

## EQU1 ## R _max <T _max (1) R _max (maximum optical density of ink having the highest density of ink used for reflective recording medium) T _max (maximum optical density of ink having the highest density of ink used for transmissive recording medium) Concentration). This is because when the same color material is applied to the medium, the optical density of the transmissive medium is lower, so when reproducing the same optical density on both the transmissive and reflective media, the color applied to the transmissive medium. This is because the material needs to have a higher concentration. In addition, for the ink of maximum density and the ink of the next highest density in each of the above groups,

[0029]

## EQU00002 ## T _max / T _max-1 <R _max / R _max-1 (2) R _max-1 (optical density of the ink having the second highest density of the ink used for the reflective recording medium) T _max-1 ( The optical density of the ink having the second highest density of the ink used for the transmission medium should be satisfied.

As is clear from the above equation (2),
Since the density additivity is difficult to be achieved especially in the high density portion of the reflective recording medium, the ratio of the reflective recording medium ink to the high density ink is made larger than that of the transparent recording medium ink.

And

[0032]

(3) T _max / T _max-1 ≤ M _max / M _max-1 <R _max / R _max-1 (3) M _max : output the maximum density level of the image data for the highest density ink in the density distribution table Input image data bit value M _max-1 : The maximum density level of the image data for the ink having the second highest density in the density distribution table is satisfied so that the input image data bit value is output. That is, by satisfying the relationship in consideration of the additivity of the density according to each recording medium, the dots actually formed by the ink of each density being overlaid on various recording media are actually The obtained ratio of optical densities can be made substantially equal to the ratio of predetermined bit values in the image data.

As described above, in order to satisfy the relations of the expressions (1) to (3), the combination of the density inks is changed for each recording medium used in this embodiment, and the inks of the respective groups are changed to the above (1). )-(3) are satisfied. In each of the above formulas, the relationship is defined only for the ratio of the maximum density and the next density, but for the inks of the third and lower densities, the predetermined bit value of the input image determined in the density distribution table, 6 in the example shown in FIG.
It can be determined according to the ratio of the values of 4, 128, 192 and 255.

[0034]

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

(Embodiment 1) FIG. 2 is a schematic perspective view of an ink jet recording apparatus according to an embodiment of the present invention.

In the figure, the recording head 2-on the carriage 1.
1, 2-2 are attached. As shown in FIG. 3, each recording head has four heads each having 64 ejection openings 20 as one structural unit (chip), which allows eight head chips to be selected from eight head chips, as will be described later. Ink of a high density can be ejected. That is, each print head has a discharge port 2
0 are arranged at a density of 360 dpi (dots / inch), and in these recording heads, for inks of similar colors, chips 2-1-1 to 2-1- 4 and chips 2-2-1 to 2-2-4.

Inks of respective densities are supplied to the respective heads from the ink tanks 4 provided corresponding to the respective heads. The carriage 1 is slidably guided and supported by a guide shaft 3, and is reciprocated along the guide shaft 3 by driving a carriage motor 7 via a drive belt 6. Recording head 2-1,
A drive signal is supplied to 2-2 via a flexible insulating belt 5 having a large number of conductors. Further, the recording medium is conveyed in the direction of the arrow in each figure by the conveyance roller and the discharge roller 8 which are driven by a conveyance motor (not shown), and is ejected from the recording head as the recording head moves. An image is recorded with the ink of a high density.

A recovery unit 10 having a cap portion 9 is disposed at a home position set outside the recording area by the movement of the carriage 1, and the ink recovery characteristic of each recording head is stabilized by the recovery processing by the recovery unit. Can be converted.

The density of each ink depends on the recording medium L which is reflective.
A bubble jet recording head (ejection port diameter 40 μm × 40 μm) was used on a C201 (product name: Canon inkjet recording paper) with a dot density of 360 dpi using a BJC-600 (product name Canon inkjet printer).
Ink ejection is performed from x64 pieces x4x2), and the area ratio is 10
A black ink was used in which the optical reflection density when recorded at 0% was the combination shown in FIG. This black ink is
BJI-201Bk (trade name: ink cartridge black manufactured by Canon Inc.) prepared by diluting with water to achieve each of the above concentrations was used. Ink I shown in FIG.
8 was used as it was on the market.

FIG. 4 is a block diagram showing the control arrangement of the above-mentioned ink jet recording apparatus.

In the figure, reference numeral 101 denotes an image input section for inputting an image signal from a host device such as a personal computer or a video device, and 102 an operation provided with various keys for setting various parameters and instructing recording start. And a combination of inks can be selected according to a recording medium used later. 103 is an RO described later.
2 shows a CPU that controls the entire recording apparatus according to various programs stored in M. Reference numeral 104 denotes a ROM that stores a program for controlling the recording apparatus. This R
The OM 104 stores a program for grayscale multiplexing input image data, which will be described later, to generate image output data.

Reference numeral 105 denotes an image processing unit for generating image output data by grayscale multiplexing input image data, which will be described later. Reference numeral 106 denotes a work area for executing various programs in the ROM 4 and temporary saving in case of an error. An area and a RAM used as an area for storing image output data to be sent to the printer unit are shown. Further, 107 denotes a printer unit that forms an image based on image output data, and has a configuration mainly shown in FIG. Reference numeral 108 is a bus line for transmitting address signals, data and control signals in the recording apparatus.

Next, the image processing for binarizing the dark and light ink of the present embodiment based on the above configuration will be described.

The binarization processing of the image data corresponding to the respective dark and light inks performed in this embodiment is the same as the binary data obtained by using this table without using the dark and light distribution table shown in FIG. This is a process that can obtain data.

That is, in the binarization process of this embodiment, the threshold value corresponding to each dark and light ink used is used, and the input image data is directly binarized without going through the density conversion process (dark and light distribution) corresponding to each ink. Is to do. In this case, similarly to the density distribution table shown in FIG. 1, a range corresponding to each of the dark and light inks with respect to the input image data is determined in advance, and is determined in consideration of the density conversion characteristics of the density distribution table in this range. Binarization is performed with a threshold value. As a result, it becomes possible to perform the same processing and binarization processing as the light and shade distribution shown in FIG. 1 in one processing.

Therefore, even when the binarization processing of the present embodiment is performed, the predetermined density signal levels (M _max , M _max-1) of the input image data relating to the above-described ranges corresponding to the respective dark and light inks. , M _max−2 , M _max−3 ) and the ratio of the optical densities realized by the respective inks are basically equal to each other, it is basically possible to achieve good gradation in a printed image. The above discussion is valid.

The binarization process of this embodiment will be described in more detail below.

The input image data has a value of 0 to 255,
As described above, it is represented by an 8-bit digital signal in which the brightest part of the density has a 0 value and the darkest part has a 255 value. This input image data has a pixel density of 3
This is for recording an image of 60 dpi, and these data sent from the host device are temporarily stored in the image memory of the RAM 106. Then, the input image data for each pixel is sequentially binarized as follows,
Binary output data M1 corresponding to each dark and light ink
Obtain ~ M4.

The input image data is first converted from 192-value to 255-value and from 128-value to 19-value according to the density signal level.
It is determined whether the data is in the range of 1-value, 64-value to 127-value, and 0-value to 63-value, and binarization is performed by the threshold value corresponding to the determined range.

In the case of input image data of 192 to 255 values, binarization is performed using 224 as a threshold value. That is, when the data is 224 or more, M1 data having a value of "1" is generated, while the data is 224.
If it is less than the value, M2 data having "1" as the content is generated. Further, in the case of input image data of 128 values to 191, binary conversion is performed using 160 as a threshold value. Similarly, in the case of data of 160 or more, M2 data is 1
When it is less than 60, M3 data is generated. Furthermore, in the case of input image data of 64 values to 127 values, 96
Is used as a threshold value, M3 data is generated when the input image data is 96 or more, and M4 data is generated when the input image data is less than 96. Furthermore, when the input image data is 63 values from 0 value, 32 is set as the threshold value, and when it is 32 or more, M4 data is generated. On the other hand, when it is less than 32, binary data having a value of "0" is generated.

As described above, according to the binarization processing of the present embodiment, the data ("1") for ejecting the inks having different densities in the descending order of the densities are M4, M3, M2, respectively. Data of M1 and M1 and "0" data indicating specific ejection are generated. As a result of this processing, as described above, the processing equivalent to the shading distribution shown in FIG. 1 and the binarization processing based thereon is performed.

Further, in this case, for convenience of explanation, assuming that the above-mentioned M _max is 100, M _max-1 is 75 ((192
/ 255) × 100), M _max / M _{max-1 in} the above equation (3) is 100/75.

On the other hand, when recording on plain paper (recycled paper EW500: made by Canon) based on the output data corresponding to the four kinds of ink generated as described above, the data M4 is shown in FIG. I1 ink is used, data M3 is I2 ink, data M2 is I3 ink, and data M1 is I6 ink.

When recording on coated paper (LC201: Canon ink jet image receiving paper), the data M
The ink set B is a combination that uses I2 ink for No. 4, I3 ink for data M3, I5 ink for data M2, and I7 ink for data M1.

Further, a transparent OHP sheet (CA10
1: When recording on a Canon inkjet OHP sheet), data M4 is I3 ink, data M3
The ink set C is a combination that uses I4 ink for the data, I7 ink for the data M2, and I8 ink for the data M1.

In the above cases, the R _max / R _max-1 value of plain paper is I6 / I3 = 1.0 /
The R _max / R _max-1 value of 0.4 coated paper is I7 / I5 = 1.2
/0.8 OHP sheet has a T _max / T _max-1 value of I8 / I7 =
It is 1.5 / 1.2, and it can be seen that all satisfy the expressions (1), (2), and (3).

Thus, depending on the recording medium used,
By changing the combination of the dark and light inks used, it is possible to obtain an image with good gradation characteristics on any recording medium without special processing such as newly changing the gamma characteristic of the image data. Could also be recorded.

(Embodiment 2) In this embodiment, I9 to I1
Eight kinds of inks of 6 were prepared. These inks have the same optical reflection density when 100% duty recording is performed on the reflective recording medium LC201 (Canon inkjet recording paper) using the Canon inkjet printer BJS600, as in Example 1. The black ink shown in FIG.

Output image data consisting of binary data corresponding to each ink was prepared in the same manner as in Example 1. Ink set D (I9, I11, I13, I15) records on coated paper, while ink set E (I10, I12, I1)
4, I16) was recorded on the OHP sheet.

The R _max / R _max-1 value of coated paper is I15.
/I3=1.2/0.8 The T _max / T _max-1 value of the OHP sheet is I16 / I15.
= 1.5 / 1.2, which means that the expressions (1), (2) and (3) are satisfied.

(Embodiment 3) In this embodiment, I9 to I1
6 inks were prepared. The density of each ink is the optical reflection density when recording is performed at 100% duty on the reflective recording medium LC201 (Canon inkjet recording paper) using the Canon inkjet printer BJS600, as in the first embodiment. Used the black ink shown in FIG.

On the other hand, output image data was prepared in the same manner as in Example 1. On the other hand, the ink set F (I9, I11,
I13, I16) was used for recording on coated paper, and ink set G (I9, I12, I14, I16) was also used for recording on coated paper.

Images having different gradation reproducibility can be recorded, and a dark tone image can be recorded by the ink set G, and a light tone image can be recorded by the ink set F.

(Comparative Example 1) For comparison, I9 of Example 2 was used.
Recording was performed using the following combinations of inks from the I16 inks different from the above-described examples.

That is, the output image data M1, M2, M
3 and M4 were prepared in the same manner as in Example 1, while
Ink set H (I9, I11, I13, I14) records on coated paper, and ink set I (I10, I10,
I12, I13, I16) was recorded on the OHP sheet. In this case, the R _max / R _max-1 value of the coated paper is I14 / I13 =
The T _max / T _max-1 value of the 1.0 / 0.8 OHP sheet is I16 / I13.
= 1.5 / 0.8 and M _Max / M _{max -1} is 100/75,
It can be seen that neither satisfies the expressions (2) and (3).

As a result, with the coated paper and the OHP sheet,
The gradation reproducibility had different impressions, and good gradation could not be obtained in each recorded image.

Comparative Example 2 As another comparative example, recording was performed using inks I17 to I20 having the densities shown in FIG. 7 as dark and light inks.

That is, the output image data M1, M2, M
3 and M4 were prepared in the same manner as in Example 1, and based on this, recording was performed on any recording medium using the ink combination shown in FIG. In this case, (1) to (3) above
Since the formula was not satisfied, recording was satisfactorily performed on the transmissive medium, whereas on the coated paper, the density was crushed, especially in the dark part.

(Others) The present invention is provided with a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for ejecting ink, particularly in the ink jet recording system. The present invention brings about excellent effects in a recording head and a recording apparatus of the type in which the state of ink is changed by the heat energy. This is because such a system can achieve high density recording and high definition recording.

Regarding its typical structure and principle, see, for example, US Pat. Nos. 4,723,129 and 4740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
It can be applied to any of the continuous type, but especially in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal in a one-to-one correspondence
It is effective because bubbles can be formed inside. Due to the growth and contraction of the bubbles, the liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable to make this drive signal into a pulse shape because bubbles can be immediately and appropriately grown and contracted, so that liquid (ink) ejection with excellent responsiveness can be achieved. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the ejection port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned specifications, US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
The structure using the specification of No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration corresponding to the ejection portion is disclosed in JP-A-59-138461. That is, according to the present invention, recording can be surely and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full line type recording head having a length corresponding to the maximum width of a recording medium which can be recorded by the recording apparatus. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads or a configuration as one recording head integrally formed.

In addition, even in the case of the serial type as in the above example, the recording head fixed to the apparatus main body or the electrical connection with the apparatus main body or the ink from the apparatus main body by being attached to the apparatus main body The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself is used.

Further, as the constitution of the recording apparatus of the present invention, it is preferable to add ejection recovery means for the recording head, preliminary auxiliary means, etc. because the effects of the present invention can be further stabilized. Specifically, heating is performed by using a capping unit, a cleaning unit, a pressure or suction unit for the recording head, an electrothermal converter or a heating element other than this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

Regarding the type or number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, or a plurality of inks having different recording colors and densities are supported. A plurality of pieces may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but it may be either the recording head is integrally formed or a plurality of combinations may be used. The present invention is also extremely effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, in the above-described embodiments of the present invention, the ink is described as a liquid, but an ink that solidifies at room temperature or lower and that softens or liquefies at room temperature may be used. Or, in the inkjet system, it is common to control the temperature of the ink itself within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within the stable ejection range. Sometimes, a liquid ink may be used. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change of the ink from the solid state to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in the standing state. You may use the ink liquefied by. In any case, by applying thermal energy such as ink that is liquefied by applying thermal energy according to the recording signal and liquid ink is ejected, or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent No. 1260, it may be configured to face the electrothermal converter in a state of being held as a liquid or a solid in the concave portion or the through hole of the porous sheet. 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, as the form of the ink jet recording apparatus of the present invention, in addition to the one used as an image output terminal of information processing equipment such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function can be used. It may be a form or the like.

[0078]

As is apparent from the above description, according to the present invention, a plurality of ink sets used for recording are selected according to the recording medium used for recording. The ink can be defined so that the optical density realized in the recording medium used corresponding to them has a predetermined linear relationship with the recording data, whereby the recording data is not subjected to any processing. Even if the recording medium used for is changed, it is possible to always record an image with good gradation.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a gradation distribution table.

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

FIG. 3 is a diagram schematically showing an ink ejection port surface of a recording head used in the above apparatus.

FIG. 4 is a block diagram showing a control configuration of the inkjet recording apparatus.

FIG. 5 is a diagram showing an ink combination used in an example of the present invention.

FIG. 6 is a diagram showing an ink combination used in another embodiment of the present invention.

FIG. 7 is a diagram showing a combination of inks used in a comparative example.

[Explanation of symbols]

1 carriage 2-1 Recording head 2-2 Recording head 2-1-1 to 2-2-4 Head chip 3 Guide shaft 4 ink tank 5 Flexible insulating belt 6 drive belt 7 Carriage motor 8 Paper ejection roller 9 Cap section 10 Recovery Unit 101 Image input section 102 Operation unit 103 CPU 104 ROM 105 image signal processing unit 106 RAM 107 printer section

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masataka Yashima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference JP 3-16733 (JP, A) JP 1 -290440 (JP, A) JP 59-52658 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41J 2/01 B41J 2/045 -2/055 B41J 2/205

Claims (6)

(57) [Claims] 1. An inkjet recording apparatus for performing recording using a plurality of inkjet heads capable of ejecting inks of similar colors having different densities, wherein the plurality of inkjet heads are provided according to a recording medium used for recording. Using a selection unit that selects a plurality of inkjet heads from among them, and a plurality of inkjet heads selected by the selection unit, gradation recording is performed on the recording medium based on ejection data corresponding to a plurality of inks used for recording. An inkjet recording apparatus comprising: a control unit for performing the above. 2. The inkjet recording apparatus according to claim 1, wherein the selection unit selects a plurality of inkjet heads of a predetermined combination from the plurality of inkjet heads. 3. The predetermined combination is determined based on a predetermined value with which the plurality of inks are associated with the print data when generating ejection data corresponding to the plurality of inks based on the print data. The inkjet recording apparatus according to claim 2, wherein the inkjet recording apparatus is an inkjet recording apparatus. 4. The ink jet recording apparatus according to claim 1, wherein the recording medium used for recording includes a transmissive medium and a reflective medium. 5. The ink jet recording apparatus according to claim 1, wherein the ink jet head uses thermal energy to generate bubbles in the ink and ejects the ink by the pressure of the bubbles. . 6. An ink jet recording method for performing recording using a plurality of ink jet heads capable of ejecting inks of similar colors having different densities, the same color having different densities depending on a recording medium used for recording. A plurality of inks are selected, and the selected plurality of inks are ejected from the plurality of inkjet heads to perform gradation recording, and an inkjet recording method is provided.