JP2001212991A - Ink jet recording apparatus and ink jet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To record an image having a higher image quality without prolonging the recording time. SOLUTION: At the time of recording on a region having specified density data or above by means of an ink jet recorder performing serial recording using a recording head 1020 having nozzle arrays ejecting a plurality of kinds of the same color ink having different density, a combination of at least two kinds of ink and an output value representing the use ratio of respective inks are outputted as record data and scanning is performed by moving a recording head relatively (41-46) by one nozzle length at a time according to the record data. Since the seams 414 of record planes 412-413 of respective inks are located at different positions, occurrence of streak is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus and an ink jet recording method, and more particularly, to a recording head having a recording element array arranged in a predetermined direction for each of a plurality of types of inks having similar colors and different densities. Is scanned on a recording medium in a direction substantially orthogonal to the arrangement direction of the recording element rows, and the type of ink ejected to each pixel and the number of ink droplets are changed to perform multi-tone recording. The present invention relates to an apparatus and an inkjet recording method.

[0002]

2. Description of the Related Art In a recording apparatus such as a printer or a copying machine, an ink jet recording method in which an ink droplet is ejected from a nozzle serving as a recording element and is made to adhere to recording paper to form an image by ink jet is low noise and low noise. It is widely used for reasons such as running cost, easy downsizing of the device, and easy colorization.

In recent years, in order to improve the recording speed, many ink jet recording apparatuses have a recording head (hereinafter, referred to as a multi-head) in which a plurality of recording elements are integrated and arranged and a plurality of ink ejection ports and flow paths are integrated. An apparatus used for performing color printing generally includes a plurality of such multi-heads.

In order to obtain a high-quality image in an ink jet recording apparatus, it is necessary that various characteristics such as coloring, gradation and uniformity be good. Of these, particularly with regard to uniformity, slight variations in the nozzle unit in the multi-head manufacturing process affect the amount of ink ejected from each nozzle and the direction of the ejecting direction during printing, and ultimately the recorded image Causes unevenness in image quality as density unevenness.

[0005] In order to suppress such image deterioration, several methods have been proposed for an ink jet recording apparatus. For example, in Japanese Patent Application Laid-Open No. Hei 5-169681,
By performing multi-pass printing using a block pattern obtained by arranging two patterns in which the arrangement of the recording pixels and the non-recording pixels are inverted in parallel in the main scanning direction as a thinning pattern, density unevenness and color unevenness are caused. There is disclosed a method for recording a high-quality image without any defect.

Japanese Patent No. 2837550 describes a technique for achieving high image quality without increasing the integration density by using a dark and light ink of the same color having a different dye concentration in an image to highlight an image. Is recorded using light ink to make the dots of the ink inconspicuous, and a dark portion with high density is recorded with dark ink.

The data processing in such a density recording method is roughly classified into two methods. The first method considers similar-color inks having different densities as one color, and turns on / off (use / use) each of the inks by multi-valued the color.
The second method is to consider the same color inks having different densities as different colors, separate them into respective colors, and then binarize to determine ON / OFF of each color. It is.

[0008]

The image recorded by the above-described method becomes smooth, but on the other hand, image deterioration due to skew and a difference in ejection amount becomes more noticeable. Therefore, when performing multi-pass printing, a larger number of passes is required, and there is a problem that the printing time becomes longer in order to obtain a high-quality image.

The present invention has been made in view of the above circumstances, and has as its object to provide an ink jet recording apparatus and a recording method capable of recording a high-quality image without increasing the recording time. I do.

[0010]

In order to achieve the above object, an ink jet recording apparatus according to the present invention comprises an ink jet recording head having a recording element array arranged in a predetermined direction for each of a plurality of types of inks having similar colors and different densities. An inkjet recording apparatus that performs multi-tone recording by scanning a recording medium in a direction substantially orthogonal to the arrangement direction of the recording element rows and changing the type of ink to be ejected and the number of ink droplets, Ink use determining means for outputting, as print data, at least two types of combinations of the plurality of types of inks and use ratios of the respective inks as print data in accordance with each predetermined tone value or more; And recording control means for controlling the driving of.

According to another aspect of the present invention, there is provided an ink-jet recording head having a recording element array arranged in a predetermined direction for each of a plurality of types of inks having similar colors and different densities. An ink jet recording method for performing multi-tone recording by scanning on a recording medium in a direction substantially orthogonal to the arrangement direction of the ink and changing the type of ink to be ejected and the number of ink droplets, wherein each gradation value is equal to or more than a predetermined value. A use ink determining step of outputting, as print data, at least two types of combinations of the plurality of kinds of inks and a use ratio of each ink; and printing controlling the driving of the print head according to the print data. And a control step.

That is, in an ink jet recording apparatus that performs serial recording using a plurality of types of inks having similar colors and different densities, at least two types of combinations of a plurality of types of inks are used in correspondence with each gradation value equal to or more than a predetermined value. The usage ratio of each ink is output as print data, and driving of the print head is controlled according to the print data.

Thus, when printing at a predetermined density or higher, a plurality of printing elements are used without performing multi-pass printing, so that the discharging direction and the discharging amount due to manufacturing variations among the printing elements are obtained. Less sensitive to differences in

Therefore, when recording areas of the same density,
The generation of streaks and unevenness is suppressed, and a high-quality image can be recorded without increasing the recording time.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

In the embodiment described below, a printer is described as an example of a recording apparatus using an ink jet recording method.

In this specification, "recording" (sometimes referred to as "printing") means not only the case where significant information such as characters and figures are formed, but also whether a person is visually significant or not. Regardless of whether or not the image has been exposed so as to be perceivable, a case where an image, a pattern, a pattern, or the like is widely formed on a recording medium or a medium is processed is also referred to.

Here, the "recording medium" is not limited to paper used in a general recording apparatus, but is widely used for cloth, plastic film, metal plate, glass, ceramics, wood,
A material that can accept ink, such as leather, is also referred to.

Further, “ink” (sometimes referred to as “liquid”) is to be interpreted as widely as the definition of “recording (printing)”, and by being applied on a recording medium, It refers to a liquid that can be used for forming an image, a pattern, a pattern, or the like, processing a recording medium, or processing ink (for example, solidifying or insolubilizing a colorant in ink applied to the recording medium).

[First Embodiment] <Schematic Description of Apparatus Main Body> FIG. 12 is a perspective view showing the structure of an ink jet printer as a first embodiment of the present invention. The recording medium 1060 inserted at the paper feed position of the printer 1000 is conveyed to the recording area of the recording head unit 1030 by the feed roller 1090. A platen 1080 is provided below the recording medium in the recording area.

The carriage 1010 has a guide shaft a104
It is configured to be movable in a direction determined by two guide shafts of 0 and a guide shaft b1050, and scans the recording area back and forth. The carriage 1010 is mounted with a plurality of printheads that eject different types of ink, and a printhead unit 1030 that includes an ink tank that supplies ink to each printhead. The type of ink used in the present embodiment and the configuration of the recording head will be described later.

At the left end of the area where the carriage can move,
A recovery unit 1100 is provided at a lower portion, and caps a discharge port of the print head during non-printing, and sucks and removes ink clogged in the discharge port. This left end is called the home position of the recording head.

Reference numeral 1070 denotes a switch section and a display element section. The switch section is used for turning on / off the power of the printer, setting various recording modes, and the like. The switch section plays a role of displaying the status of the printer.

<Configuration of Nozzle> FIG.
FIG. 020 is an enlarged cross-sectional view of one nozzle. In the ink jet printer according to the present embodiment, a heating element, which is an electric-to-heat converter, is arranged corresponding to each ink ejection port, and a drive signal corresponding to recording information is applied to the heating element to eject ink from nozzles. The system is adopted. Heating element 30
Numeral 0 indicates that each nozzle can generate heat independently.

The ink in the nozzle, which has been rapidly heated by the heat generated by the heating element 300, forms bubbles due to film boiling, and the pressure of the bubble generation causes the ink droplets 35 as shown in FIG.
0 is ejected toward the recording medium 310 and adheres onto the recording medium to form characters and images. At this time, the volume of each ejected ink droplet is about 1 to 100 ng.

Each of the discharge ports 230 is provided with an ink liquid path communicating with the discharge port, and a common liquid for supplying ink to these liquid paths is provided behind the portion where the ink liquid path is provided. A chamber 320 is provided. In the ink liquid passage corresponding to each of the ejection ports, an electric-to-heat converter 300 for generating thermal energy used for ejecting ink droplets from these ejection ports and an electrode wiring for supplying power thereto are provided. Is provided.

The heating element 300 and the electrode wiring are formed on a substrate 330 made of silicon or the like by a film forming technique. A protective film 360 is formed on the heating element 300 so that the ink does not directly contact the heating element. further,
By stacking a partition wall 340 made of a resin or a glass material on this substrate, the above-described discharge port, ink liquid path, common liquid chamber, and the like are formed.

As described above, the recording method using the heating element, which is an electric-heat conversion element, is generally called a bubble jet recording method because it uses bubbles formed by applying thermal energy when ejecting ink droplets. ing.

<Control Configuration> FIG. 14 is a block diagram showing a control configuration of the ink jet printer 1000 of the present embodiment.

From the host computer, data of characters and images to be recorded (hereinafter referred to as image data) is input to a receiving buffer 4010 of the printer. Further, data for confirming whether data is correctly transferred and data for notifying the operation state of the printer are transmitted from the printer to the host computer. The data in the reception buffer 4010 is transferred to the memory unit 4030 and temporarily stored in a RAM (random access memory) under the control of the CPU 4020.

The drive mechanism control unit 4040 includes a CPU 402
A mechanical unit 4050 such as a carriage motor or a line feed motor is driven by a command from 0. The sensor / SW control unit 4060 outputs signals from the sensor / SW unit 4070 including various sensors and SWs (switches) to the CPU 4020.
Send to

The display element control section 4080 controls a display element section 4090 composed of an LED of a display panel group, a liquid crystal display element and the like in accordance with a command from the CPU. The printhead control unit 4100 controls the printhead 1020
Control. Further, temperature information indicating the state of the recording head 1020 and the like are detected and transmitted to the CPU 4020.

<Ink Used> In this embodiment, color recording is performed using four color inks of yellow, magenta, cyan, and black. Of these, five types of cyan and magenta having different densities are used. Printing is performed by discharging ink from the corresponding print head.

FIG. 1 is a graph showing input values of 0 to 255 and output values of each of the five types of cyan inks A to E having different densities used in the present embodiment. By quantizing each of the output values, a pixel is recorded on the recording medium using the corresponding ink.

In this figure, curves 101 to 105 represent output values of cyan inks A to E, respectively.
The densities of the five types of cyan inks A to E are A <B <C <D.
<E.

FIG. 2 shows an example in which the output of each of the cyan inks A to E for the input value 128 is obtained from the graph of FIG. As shown, for the input value 128, the output value of each ink is as follows: cyan ink A = 64 cyan ink B = 128 cyan ink C = 64 cyan ink D = 0 cyan ink E = 0.

Therefore, the respective inks are used on the recording medium at a ratio of cyan ink A = 25%, cyan ink B = 50%, cyan ink C = 25%, cyan ink D = 0%, and cyan ink E = 0%. Will be recorded.

For this reason, when a certain area is recorded with an input value of 128, each pixel in the area has the cyan ink
Recorded using E in the above ratio. Since the usage ratio of the cyan inks A to E is the same in each raster, each raster is recorded by three different nozzles of the cyan ink A, the cyan ink B, and the cyan ink C.

That is, since each raster is recorded by a plurality of nozzles ejecting inks of similar colors having different densities,
Deviation in the ejection direction and variation in the ejection amount of each nozzle, which causes image deterioration, are averaged and suppressed, and the same effect as in the case of performing multi-pass printing can be obtained.

However, in this case, unlike normal multi-pass printing, inks of different densities are ejected from three nozzles used for printing each pixel, so one type of ink is used for each color. In normal multi-pass recording,
The printing result is different from the printing result when three different nozzles are used by performing three-pass printing.

Incidentally, the pixels recorded with the ink having the lowest density are not so conspicuous visually, and when such pixels are dispersed to some extent, the deviation or the discharge amount due to the direction of ink discharge is considered. It is less susceptible to image degradation factors due to variations in image quality.

For an input value having a small value, printing using a plurality of types of inks has little effect, and conversely, printing has been performed with a high density ink in a low density area. If there is a part, a granular feeling is given, which causes deterioration of image quality.

In this embodiment, taking such points into consideration,
For a pixel having a small input value, printing is performed using only the ink (A) having the lowest density. For the same reason, only one type of ink is used without using inks having different densities even for yellow in which a density difference is difficult to visually recognize.

<Printing Head> FIG. 3 is a schematic view of the printing head 1020 used in the present embodiment as viewed from the ejection surface side.

As shown in the figure, the recording head 1020 of the present embodiment has 1
It has two nozzle rows, the length 3D of each nozzle row is equal, and the distance 3E between nozzles is 1/3 of the nozzle length.

The nozzle arrays 31 to 35 are nozzle arrays for ejecting cyan ink, and eject cyan inks A to E, respectively. The nozzle row 36 is a nozzle row that discharges yellow ink. The nozzle arrays 37 to 3B are nozzle arrays that eject magenta ink, and eject magenta inks A to E, respectively. The nozzle row 3C is a nozzle row that discharges black ink.

A recording head 1020 having a nozzle row having such a configuration is mounted on a carriage, and recording is performed by discharging ink droplets from each nozzle while being moved in the scanning direction indicated by the arrow in the drawing.

Here, regarding the densities of the five types of magenta inks A to E, there is a relationship of A <B <C <D <E, as with the cyan inks A to E described above.

<Recording State> FIG. 4 is a diagram for explaining a state in which an area having an input value of 128 is recorded on a recording medium by the printer of this embodiment having the recording head having the nozzle configuration shown in FIG.

In FIG. 4, the left side shows the relative position of the recording head 1020 with respect to the recording medium.
.., In the order of 46, the nozzle length 3D shown in FIG.
The recording is performed while moving in the X direction and scanning in the X direction.
In the figure, for ease of explanation, the relative position is shown to move obliquely downward, but in reality, the relative position of the recording head 1020 with respect to the recording medium moves in the Y direction in the figure.

Reference numerals 411 to 413 denote recording planes recorded with cyan inks A to C, respectively. In the figure, for ease of explanation, the recording planes 413 for cyan ink C, the recording planes 412 for cyan ink B,
The recording is performed in the order of the recording planes 411 of the cyan ink A.

Reference numeral 414 denotes a state after printing. In the recorded area, the connecting position 421 of the cyan ink A, the connecting position 422 of the cyan ink B, and the connecting position 423 of the cyan ink C are different from each other. Position.

In this manner, the recording head 1020
An image is formed on the recording medium by sequentially repeating the scanning in the direction and the relative movement in the Y direction with respect to the recording medium.
In the example shown here, since the input values of all the pixels in the recording area are 128, as described above, the cyan ink A is 25%, the cyan ink B is 50%, and the cyan ink C is 25%. The recording is performed using the ratio of.

As described above, according to this embodiment,
Pixels in a region having a predetermined density or higher are recorded by a plurality of nozzles that discharge inks of different densities, so that the skew of the individual nozzles and variations in the discharge amount are averaged, and deterioration in image quality is suppressed. Is done.

Further, since an image is formed by each nozzle row scanning the print area once, the print speed can be improved as compared with the normal multi-pass print. Furthermore,
Because the connection position of the area recorded by each ink is different,
It is also possible to reduce the occurrence of streaking at the joints, which causes image quality deterioration when performing one-pass printing.

[Second Embodiment] According to the above-described first embodiment, there is an effect that the deviation of each nozzle and the variation of the ejection amount are averaged, but on the other hand, a plurality of types of similar colors are obtained. Since the area where ink is overprinted is formed,
Texture may occur in this part. Further, it is necessary to use a recording medium having a large ink capacity (ink ejection amount) that can be absorbed per unit area, and the usable recording medium is limited.

In the second embodiment, in order to prevent the occurrence of such a texture and to enable use of various recording media, each pixel in an area having a predetermined density or more is replaced with a plurality of pixels of similar colors having different densities. Recording is performed with any one of the inks.

The configuration of this embodiment and the type of ink used are the same as in the first embodiment, and a description thereof will be omitted. Hereinafter, only the characteristic portions of the present embodiment will be described.

In this embodiment, five types of inks having different densities are used as cyan and magenta inks.
The density value of the input pixel is quantized, the ratio of ink to be used is determined according to the quantization value, a random number is generated for each pixel according to the determined ratio, and the type of ink to be used with the value of the random number is determined. decide. At this time, cyan or magenta ink used for recording of each pixel uses only one kind of ink of the same color to prevent overlapping of the same color ink in the pixel.

FIG. 5 is a graph showing the relationship between the quantization value and the ratio of the ink used in this embodiment for cyan. Reference numeral 501 denotes a cyan ink A, 502 denotes a cyan ink B, 503 denotes a cyan ink C, 504 denotes a cyan ink D, and 505 denotes a cyan ink E use ratio. That is, a quantization process is performed on each pixel, and each ink is used at a predetermined ratio according to the quantization result. FIG. 7 is a table showing the graph of FIG. 5 by numerical values. In practice, it is better to store the data in such a table format in a memory or the like.

FIG. 6 is a diagram showing the flow of processing in this embodiment. At first, the value of 0 input as the density value of the pixel
The value of ~ 255 is quantized to 13 values (601). Here, the case where the number of quantization steps is 13 will be described.
The number of steps is not limited to this value. next,
A random number from 0 to 100 is generated for each pixel (602), and which ink is used to print each pixel is determined based on the quantization value and the value of the random number (603).

As a specific example, a cyan density value of 11
A process for recording a fixed area having 7 will be described.
When the input value 117 is quantized to 13 values, it is quantized to 5 or 6 with a probability of 50%, respectively. Next, random numbers from 0 to 100 are generated. Then, the type of cyan ink used to record each pixel is determined according to the generated random number value according to the graph shown in FIG.

FIG. 8 is a graph showing the relationship between the value of the random number when the quantization value is 6 and the type of cyan ink used. The ratio of the ink used to the quantization value 6 is shown in FIG.
As shown in the figure, the ratio of the cyan ink A is 25%, the ratio of the cyan ink B is 50%, and the ratio of the cyan ink C is 25%.
Therefore, for random number values 0 to 100, cyan ink A for values of 0 to 25, cyan ink B for values of 25 to 75, and cyan ink C for values of 75 to 100
Assign to use.

In this manner, even if only one kind of similar color ink is used to record each pixel in the area of the same density, it is possible to prevent a texture from being generated in a specific order.

In this case, since the probability of being quantized to the quantized value 5 or 6 is 50% each, the more appropriate ink use is determined from the ink use ratio for both the quantized values 5 and 6 as follows. The ratio can be determined.

As shown in FIG. 7, the use ratio of each ink with respect to the quantization value 5 is: No recording = 8% Cyan ink A = 42% Cyan ink B = 42% Cyan ink C = 8% Cyan ink D = 0% cyan ink E = 0%.

On the other hand, the use ratio of each ink with respect to the quantization value 6 is as follows: No recording = 0% Cyan ink A = 25% Cyan ink B = 50% Cyan ink C = 25% Cyan ink D = 0% Cyan ink E = 0%.

Therefore, adding both values by 50%,
The use ratio of each ink with respect to the input value 117 is not recorded = 0.08 × 0.5 + 0 × 0.5
= 4% cyan ink A = 0.42 x 0.5 + 0.25 x
0.5 = 33.5% cyan ink B = 0.42 × 0.5 + 0.5 × 0.
5 = 46% cyan ink C = 0.08 × 0.5 + 0.25 ×
0.5 = 16.5% Cyan ink D = 0 × 0.5 + 0 × 0.5 = 0% Cyan ink E = 0 × 0.5 + 0 × 0.5 = 0% In the graph shown in FIG. 8, the value of the random number is associated with the ink to be used.

In this embodiment, random numbers are generated so that the type of ink used for printing is random. However, the correspondence between the quantization value and the ink used is recorded according to the usage ratio for each ink. Any method is acceptable.

Also, by controlling the dither matrix for each ink or changing the threshold value within an arbitrary range when performing multi-valued error diffusion, a plurality of inks of the same color can be recorded in the same pixel. It is possible to control not to use it.

As described above, according to the present embodiment,
Since a plurality of types of inks of the same color are not used for the same recording, the inks of the same color are prevented from being overprinted on the recording medium in the same density area, and the generation of texture due to the overlapping of the same color inks is suppressed. It becomes possible.

[Third Embodiment] In a printer that performs serial printing, a streak-like line is visually recognized at the boundary (joint) of printing areas by each scan, which causes deterioration in image quality.

This embodiment improves the image quality of the boundary between recording areas by utilizing the fact that the state of the boundary formed on the recording medium varies depending on the density of dots recorded in the ink jet printer. is there.

The configuration of this embodiment and the type of ink used are the same as in the first embodiment, and a description thereof will be omitted. Hereinafter, only the characteristic portions of the present embodiment will be described.

FIG. 9 shows a state in which the density of recording dots is low and dots are recorded at a distance without overlapping. In FIG. 9, reference numeral 90 denotes a nozzle row, 91 denotes a boundary portion of an image printed in each scan, and 95 denotes a recording dot. In this figure, the nozzle row 90 at the first position 92 moves in the main scanning direction to form an image. Next, it moves by the nozzle length in the sub-scanning direction to a position 93 relative to the recording medium. An image is formed by sequentially repeating this operation.

On the other hand, FIG. 10 shows a state in which the density of the recording dots is small and the dots are recorded so as to overlap each other. In FIG. 10, reference numeral 100 denotes a nozzle row, 101 denotes a boundary portion of an image printed in each scan, and 105 denotes a print dot. In this figure, the recording head 100 at the first position 102 moves in the main scanning direction to form an image. Next, 1 relative to the recording medium in the sub-scanning direction.
Move to the position of 03 by the nozzle length. An image is formed by sequentially repeating this operation.

When the states of the recording dots in both images are compared, in FIG. 9, since the recording dots are dispersedly recorded, there is no difference in the state of the recording dots between the boundary portion 91 and the other portions. A similar image is formed. On the other hand, in FIG. 10, the overlapping state of the recording dots differs between the boundary portion 101 and the other portions. This is due to the time lag at which the recording dots are formed.

That is, the two dots in the next row partially overlap the recording dots 105A formed in the first scan, but the boundary dots in the recording dots formed in the second scan Recording dot 1 on 101
In 05B, only one dot in the next row partially overlaps. For this reason, the density of the boundary portion is visually recognized as a streak unlike the other portions.

In this embodiment, when printing is performed using a plurality of inks of the same color having different densities, the printing duty (printing rate) of each ink is limited so that the printing dots do not overlap, thereby reducing the quality deterioration. This makes it possible to suppress the occurrence of streaks at the boundary portion.

FIG. 11 is a diagram showing an example of recording an image according to the present embodiment. Here, an example is shown in which four types of similar color inks having different densities are used to print images at a discharge rate of 25%.

In FIG. 11, reference numeral 111 denotes a recording head, which includes a nozzle array 11A for discharging ink A, an ink B
, A nozzle row 11C for discharging ink C, and a nozzle row 11D for discharging ink D. 112 is a recording state of the ink A on the recording medium, 113 is a recording state of the ink B on the recording medium, 114 is a recording state of the ink C on the recording medium, 1
Reference numeral 15 denotes a recording state of the ink D on the recording medium. Reference numeral 116 denotes the ejection amount when four planes of ink A to ink D are superimposed on the recording medium, and 119 denotes recording dots of each ink which are recorded when the recording head 111 is at the position of 118.

As shown in this figure, in each plane of inks A to D, since the recording dots are recorded in a state where the recording dots are dispersed at a coarse recording density, the boundary portions between the recording areas by each scan are printed. No streaks are visible. In addition, since the nozzle rows do not record the same area in one scan, the recording dots recorded in one scan do not overlap each other even on a recording medium on which recording dots recorded in each plane are superimposed. It becomes a dispersed state. As a result, the occurrence of streaks at the boundary between recording areas due to each scan is suppressed.

In the above-described example, the recording when the ejection amount is limited to 25% using four kinds of the same color inks is schematically shown. However, the composition of the ink, the ejection amount, the type of the recording medium, the resolution, The conditions under which recording dots are dispersedly formed differ depending on the quantization method and the like. Therefore, in addition to the conditions shown in the above example, if the recording dots are formed so as to be dispersed without overlapping each other, it is possible to prevent the occurrence of streaks at the boundary portion and suppress the image quality deterioration. is there.

By combining this embodiment with the first or second embodiment, it is possible to more effectively suppress the deterioration of the image quality of a recorded image.

[Other Embodiments] In the above-described embodiments, the means for generating thermal energy (eg, an electrothermal converter, laser light, ), And by using a method in which a change in the state of the ink is caused by the thermal energy, it is possible to achieve high-density and high-definition recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding the nucleate boiling to an electrothermal transducer arranged corresponding to the sheet or the liquid path holding the Since thermal energy is generated in the electrothermal transducer and film boiling occurs on the heat-acting surface of the recording head, bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis can be formed. It is valid.

The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.

As the pulse-shaped driving 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 the configuration of the recording head, in addition to the combination of a discharge port, a liquid path, and an electrothermal converter (a linear liquid flow path or a right-angled liquid flow path) as disclosed in the above-mentioned specifications, The configurations described in U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose a configuration in which the heat acting surface is arranged in a bending region, are also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration in which a common slot is used as a discharge section of an electrothermal transducer for a plurality of electrothermal transducers, and an opening for absorbing pressure waves of thermal energy is discharged. A configuration based on JP-A-59-138461, which discloses a configuration corresponding to each unit, may be adopted.

In addition to the cartridge-type recording head in which the ink tank is provided integrally with the recording head itself described in the above embodiment, the recording head is electrically connected to the apparatus main body by being mounted on the apparatus main body. A replaceable chip-type recording head, which enables a simple connection and supply of ink from the apparatus main body, may be used.

In this case, the ink tank and the recording head may be integrally formed to constitute a replaceable ink cartridge. However, the ink tank and the recording head may be configured to be separable so that the ink runs out. In such a case, only the ink tank may be replaced at the time.

It is preferable to add recovery means for the print head, preliminary auxiliary means, and the like to the configuration of the printing apparatus described above, since the printing operation can be further stabilized. Specific examples thereof include capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof. It is also effective to provide a preliminary ejection mode for performing ejection that is different from printing, in order to perform stable printing.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but may be a single recording head 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.

In the above-described embodiment, the description has been made on the assumption that the ink is a liquid. However, even if the ink solidifies at room temperature or lower, the ink that softens or liquefies at room temperature is used. Or, in the ink jet method, generally, the temperature of the ink itself is controlled 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 temperature rise due to thermal energy as energy for changing the state of the ink from the solid state to the liquid state, the temperature is positively prevented.
Alternatively, in order to prevent evaporation of the ink, an ink which solidifies in a standing state and 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, the ink is disclosed in JP-A-54-5
No. 6,847, or Japanese Patent Application Laid-Open No. 60-71260, in which the porous sheet is opposed to the electrothermal converter while being held as a liquid or solid substance in the concave portion or through hole of the porous sheet. It may be. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but can be applied to a single device (for example, a copier, a facsimile). Device).

Further, an object of the present invention is to supply a storage medium (or a recording medium) recording software program codes for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (a computer) of the system or the apparatus. Or a CPU or MPU) reads out and executes the program code stored in the storage medium,
Needless to say, this is achieved. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.
In addition, by the computer executing the readout program code, not only the functions of the above-described embodiments are realized, but also based on the instructions of the program code,
The operating system (OS) running on the computer performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion card 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. , The CPU provided in the function expansion card or the function expansion unit performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

[0100]

As described above in detail, according to the present invention, when printing at a predetermined density or higher, a plurality of printing elements are used without performing multi-pass printing. It is less likely to be affected by differences in the ejection direction and the ejection amount due to manufacturing variations.

Therefore, when recording areas of the same density,
The generation of streaks and unevenness is suppressed, and a high-quality image can be recorded without increasing the recording time.

[Brief description of the drawings]

FIG. 1 is a graph showing an output value of each ink with respect to an input value.

FIG. 2 is a diagram illustrating an output value of each ink with respect to an input value of 128 in the graph of FIG.

FIG. 3 is a diagram illustrating a nozzle configuration of the recording head according to the first embodiment.

FIG. 4 is a schematic diagram illustrating a state of one-pass printing according to the first embodiment.

FIG. 5 is a graph illustrating a relationship between a quantization value and a usage ratio of ink according to a second embodiment.

FIG. 6 is a diagram illustrating a flow of image signal processing according to a second embodiment.

FIG. 7 is a diagram illustrating a usage ratio of each similar color ink to a quantization value.

FIG. 8 is a graph showing a correspondence between a random number value and an ink used for a quantization value of 6;

FIG. 9 is a diagram illustrating a state where recording dots are dispersedly recorded.

FIG. 10 is a diagram illustrating a state where recording dots are recorded in an overlapping manner.

FIG. 11 is a diagram schematically illustrating a recording example of an image according to a third embodiment.

FIG. 12 is a perspective view of an inkjet printer according to a preferred embodiment of the present invention.

FIG. 13 is an enlarged sectional view of the vicinity of a heating element of a recording head.

FIG. 14 is a control block diagram of the ink jet printer of FIG.

[Explanation of symbols]

 1020 Recording head 41 to 46 Relative position of recording head 411 to 413 Recording plane of each ink 414 Connecting position between recording areas of each ink

Claims (11)

[Claims] An ink jet recording head having a recording element array arranged in a predetermined direction for each of a plurality of types of inks having similar colors and different densities is formed on a recording medium in a direction substantially orthogonal to the arrangement direction of the recording element arrays. What is claimed is: 1. An ink jet recording apparatus that performs multi-tone printing by changing the type of ink to be ejected and the number of ink droplets, wherein at least two of said plurality of kinds of inks correspond to each predetermined tone value or more. An ink jet printing apparatus comprising: a used ink determining unit that outputs a combination of types and a use ratio of each ink as print data; and a print control unit that controls driving of the print head according to the print data. . 2. The printing control device according to claim 1, wherein the printing control unit uses the at least two types of inks in accordance with a usage ratio of each of the inks in each of the pixels in the area when printing the area having the predetermined or higher gradation. 2. The ink-jet recording apparatus according to claim 1, wherein the driving of the recording head is controlled so as to discharge the ink by an amount. 3. The printing control unit according to claim 1, wherein when printing the area having the predetermined or higher gradation, one of the at least two types of ink is applied to each pixel in the area. 2. The ink jet recording apparatus according to claim 1, wherein the driving of the recording head is controlled so as to select and discharge the ink in accordance with a usage ratio. 4. The print control unit according to claim 1, wherein the print control unit controls the driving of the print head with a print duty such that pixels printed by each print element row do not overlap each other. 3. The ink jet recording apparatus according to claim 1. 5. A transporting means for transporting the recording medium by a length of one recording element row after each scan, wherein the recording element rows of the same color ink are arranged in a direction along the arrangement direction. The inkjet recording apparatus according to any one of claims 1 to 4, further comprising: 6. A method for performing color printing using cyan, magenta, yellow and black inks, wherein a plurality of types of inks having different densities are used for cyan and magenta. Items 1 to 5
The inkjet recording device according to any one of the above. 7. The recording head according to claim 1, wherein the recording head ejects ink using thermal energy, and includes a thermal energy converter for generating thermal energy applied to the ink. Item 7. An ink jet recording apparatus according to any one of Items 1 to 6. 8. An ink jet recording head having a recording element array arranged in a predetermined direction for each of a plurality of types of inks of similar colors and different densities, on a recording medium in a direction substantially orthogonal to the arrangement direction of the recording element arrays. An ink jet recording method for performing multi-gradation recording by changing the type of ink to be ejected and the number of ink droplets, wherein at least two of the plurality of types of inks correspond to predetermined gradation values or more. An ink jet recording method comprising: a use ink determining step of outputting a combination of types and a use ratio of each ink as print data; and a print control step of controlling driving of the print head according to the print data. . 9. The printing control step includes, when printing an area having the predetermined gradation or higher, applying the at least two types of ink to each pixel in the area according to the usage ratio of each ink. 9. The ink jet recording method according to claim 8, wherein the driving of the recording head is controlled so as to discharge the ink by the amount. 10. The printing control step includes, when printing an area having the predetermined or higher gradation, applying one of the at least two types of ink to each pixel in the area. 9. The ink jet recording method according to claim 8, wherein the driving of the recording head is controlled so as to selectively perform ejection according to a usage ratio. 11. The printing control step according to claim 8, wherein the printing control step controls the driving of the printing head with a printing duty such that pixels printed by each printing element row do not overlap each other. 3. The inkjet recording method according to item 1.