JP2875641B2 - Inkjet 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 ink jet recording method for recording an image having a gradation by using a recording head having a plurality of ink discharge ports.

[0002]

2. Description of the Related Art In a conventionally known ink jet recording system, a plurality of ink droplets land on substantially the same spot on a recording material to form one dot, and the number of landed ink droplets is reduced. A so-called multi-droplet system that expresses a gradation by changing it is effective. In particular, in a method in which bubbles are generated in ink by thermal energy and the ink is ejected in accordance with the generation of the bubbles, it is difficult to greatly change the size of one ink droplet. There is an advantage that discharge ports (hereinafter, referred to as nozzles) can be arranged at a high density. By using the multi-droplet method, a high-density and high-gradation image can be obtained.

[0003]

However, in the conventional multi-droplet method, one pixel is formed by a plurality of ink droplets ejected from one ink ejection port during one scan, so that the ink for each ejection port is required. If the volume of the droplets varies, there is a problem in that streaks (streaks) and density unevenness (spots) occur in an image that should be originally uniform.

In order to avoid these problems, in the conventional multi-droplet system, the recording head must be manufactured very precisely in order to minimize the variation in the volume of the ink droplets between the discharge ports. As a result, there have been problems such as an increase in manufacturing cost and a decrease in manufacturing yield. Also, as a method of eliminating density unevenness by software, a method of changing the number of ink droplets ejected so as to slightly cancel the volume of the ink droplets between the ejection ports using image processing such as an error diffusion method has been proposed. However, there is a problem that incorporating such image processing increases the production cost of the system. Further, even if such an image processing method is used, it is necessary to readjust the number of ink droplets to be ejected when the variation in the volume of the ink droplets between the discharge ports changes with time, which causes a problem that the maintainability is poor. Had.

An object of the present invention is to provide an ink jet recording method capable of obtaining a uniform gradation regardless of the aging of a recording head.

[0006]

Means for Solving the Problems To achieve the above object,
In the present invention, ink droplets are ejected from a plurality of ink ejection ports.
An ink jet recording method in which a gradation image is formed by landing at substantially the same position on a recording material by a plurality of main scans
In addition , an image is formed in accordance with an ink ejection port driving rule predetermined for each gradation so that the frequency of use of the ink ejection ports used for obtaining each gradation is substantially uniform.

Another aspect of the present invention is an ink jet recording method for forming a gradation image by landing ink droplets from a plurality of ink discharge ports at substantially the same position on a recording material by a plurality of main scans. When driving each ink ejection port to land a maximum of N ink droplets, the presence or absence of ink ejection for the nth (n = 1 to N) ink droplet is determined for each ink ejection port. The frequency of use of each ejection port during image formation is set to a predetermined value or less.

Further , in another aspect of the present invention , main scanning is performed a plurality of times from 0 to N ink droplets from a plurality of ink ejection ports.
It is required to form a an inkjet recording method for forming a is allowed to gradation image landed on substantially the same position on the recording material, the gradation level of each pixel m (0 ≦ m ≦ N) by When determining the presence or absence of an ink droplet, when the n-th (n = 1 to N) ink droplet is to be ejected, f (m, n) = 1 when the droplet is not ejected Assuming that f (m, n) = 0, for each of the above n (n = 1 to N),

[0009]

(Equation 3)

It is determined whether each ink ejection port is used or not.

Here,

[0012]

(Equation 4)

It is preferable to determine f (m, n) such that

[0014]

According to the present invention having the above structure, a plurality of main units are provided.
One pixel is formed by a plurality of ink droplets by scanning.
That is, a plurality of ink droplets are substantially
Since they land at the same position, the fixability is improved. Also, f
By determining (m, n), the frequency of use of each nozzle is made uniform, and there is no problem caused by excessive use of a specific nozzle.

In order to prevent a specific nozzle from being used at a high frequency, for example, when printing only a few drops in one pixel, the number of the ink drop to be printed is determined using a random number. A method is also conceivable. However, the method using a random number not only complicates the apparatus, but also causes a problem on an image. The reason is that, in the case where approximately two or three ink droplets are landed at substantially the same position and recorded, a slight difference in image density occurs depending on the time difference between the landing of these ink droplets. Therefore, unevenness due to the random number is generated.

According to the present invention, since f (m, n) is determined according to the present invention, the recording method for one image density is constant, and density unevenness occurs. Never.

In addition,

[0018]

(Equation 5)

This corresponds to a case where each nozzle is used most uniformly when the image level to be recorded appears on average.

[0020]

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

First, a recording method on which the present invention is based will be described. In the multi-droplet method, a plurality of ink droplets that land on substantially the same spot in the above-described multi-droplet method are ejected from different nozzles in different scans. It can be made smaller.

However, in the above-mentioned new method, the nozzles for discharging the first droplet, the second droplet,... If the required number of droplets are ejected sequentially from the first droplet and recorded, the nozzles that eject the first droplet are used in both a high-density region and a low-density region, and the frequency of use increases. Become.

Therefore, the durable life of the recording head is governed by the nozzles that eject the first droplets, and the life of the recording head may be significantly shortened.

In the recording head, the size of the droplet may slightly change depending on the usage history. However, if each nozzle is used uniformly, the image density changes only slightly, and there is almost no problem. In contrast, the new method changes the gradation of an image.

Further, during the image recording, the vicinity of the nozzle group for forming the low density area generates a remarkable amount of heat, which tends to cause a failure due to a rise in temperature.

Embodiment 1 FIG. 1 is a schematic perspective view of an ink jet recording apparatus according to an embodiment of the present invention. In the drawing, reference numeral 1 denotes a recording head provided with 128 nozzles (discharge ports) at a density of 16 nozzles / mm, and each nozzle has a heater (see FIG. 1) for generating discharge energy in a flow path communicating therewith. (Not shown). The heater generates heat in response to the applied electric pulse, thereby causing film boiling in the ink, and the ink is ejected from the nozzles as bubbles grow due to the film boiling. In this embodiment, the ejection frequency of each nozzle is 2 kHz.

Reference numeral 4 denotes a carriage for mounting and moving the recording head 1, and the carriage 4 moves while being guided by two guide shafts 5A and 5B which are slidably engaged at a part thereof. Reference numeral 6 denotes an ink supply tube for supplying ink from a not-shown ink tank to the recording head 1. Reference numeral 7 denotes a flexible cable for transmitting a drive signal or a control signal based on print data from a control unit (not shown) to a head drive circuit provided in a part of the print head 1. Both the ink supply tube 6 and the flexible cable 7 are made of a flexible member so as to follow the movement of the carriage 4.

The carriage 4 is stretched in parallel with the guide shafts 5A and 5B and is connected to a part of a belt (not shown) for moving the carriage 4, and this belt is driven by a carriage motor (not shown). Thereby, the carriage 4 can be moved.

Reference numeral 3 denotes a guide shaft 5A, 5B whose longitudinal direction is
And a platen extending in parallel with. Reference numeral 2 denotes a recording paper as a recording material. The recording head 1 can perform recording by discharging ink to a portion of the recording paper 2 facing the discharge port as the carriage 4 moves.

FIG. 2 shows a schematic configuration of the control system circuit in the embodiment shown in FIG. Here, reference numeral 201 denotes a main controller which controls the entire apparatus such as a discharge timing, and includes, for example, a CPU (Central Processing Unit), a program ROM (Read Only Memory), and a work RA.
A one-chip microprocessor with a built-in M (random access memory) or the like is usually used. The main controller 201 transmits the image data signal to the host computer 203.
, And stores it in the frame memory 205 for the buffer in frame units. Then, at the time of image recording (at the time of ink ejection), the main controller 201 controls the driving of the carriage feed motor 209 through the first motor driver 207 and controls the driving of the paper feed motor 213 through the second motor driver 211. . With this,
Based on the image data read from the frame memory 205, the image data is converted into gradation data corresponding to the present system (printing apparatus), and the ejection of the head 1 is controlled via the driver controller 215 and the head driver 217 (described in detail below).
Is performed, thereby performing gradation image recording on the recording paper 2.

Next, a method for printing at 17 gradations using the present apparatus, that is, a method in which several drops of ink per pixel
A method for performing recording by changing the range is described.

FIG. 3 is a conceptual diagram for explaining the recording method of this embodiment. Here, 1 is a schematic representation of a recording head, and 128 nozzles are arranged in the vertical direction in the figure. Now, for convenience of description, the nozzle numbers are 1, 2,...

When recording on the recording paper 2, first,
Printing is performed while moving the carriage using only the nozzles 121 to 128. As a result, N
o. Pixels 1 to 8 are recorded with 0 or 1 ink droplet.

Next, the recording paper 2 is moved upward by 8 pixels (in the figure, the head is relatively moved downward for convenience). Recording is performed using nozzles 113 to 128. As a result, no. The nozzles of Nos. 113 to 120 are of the previous No. Nos. 121 to 128 recorded by the nozzles.
The pixel portions of Nos. 1 to 8 are recorded. Nozzles 121 to 128 are newly No. 9 to 16 pixels will be recorded.

Accordingly, No. Pixels 1 to 8 are recorded with 0 to 2 ink droplets per pixel.

Next, the recording paper 2 is fed upward by 8 pixels again. Recording is performed using 105 to 128 nozzles. When such recording is sequentially repeated, when the 16th recording is completed, No. Pixels 1 to 8 are recorded with 0 to 16 drops of ink, and 17 gradations of recording are obtained.

By repeating the recording in the same manner from the 17th time onward, an image of 17 gradations can be obtained over the entire screen. At the lowermost end of the image, recording is sequentially stopped for eight nozzles from the bottom for each scan to form an image end.

For example, N
o. Focusing on the pixel of No. 1, nozzle No. 1 1,9,
17, 25, 33, 41, 49, 57, 65, 73, 8
1, 89, 97, 105, 113, 121 (the order of recording is the reverse), the ink droplets are formed from a total of 16 nozzles. An inconspicuous image will be obtained.

In this embodiment, the presence / absence of ink ejection f (m, n) is determined according to the following Table 1, corresponding to the density gradation of each pixel.

In Table 1, the n-th ink droplet corresponds to the ink droplet ejected from each of the 16 nozzles. For example, as shown in the above example, No. When attention is paid to the pixel of No. 1, The nozzle of No. 121 ejects the first ink droplet. The nozzle of No. 113 ejects the second ink droplet. No. 105 ejects the third ink droplet. No. 97 ejects the fourth ink droplet. No. 89 ejects the fifth ink droplet. No. 81 ejects the sixth ink droplet. No. 73 ejects the seventh ink droplet. No. 65 ejects the eighth ink droplet. Nozzle No. 57 ejects the ninth ink droplet, No. 49 ejects the tenth ink droplet. 41 nozzle is 11th
The No.th ink droplet is ejected. 33 nozzles are the first
The second ink droplet is ejected. No. 25 ejects the thirteenth ink droplet. Nozzle No. 17 ejects the fourteenth ink droplet. No. 9 ejects the fifteenth ink droplet. One nozzle ejects the sixteenth ink droplet.

That is, in Table 1, f (m, n) = 1
In the case of, the ink droplet is ejected, and f (m, n) = 0
At this time, control is performed so that the ink droplet is not ejected.
Therefore, for example, when the gradation m = 1, the first ink droplet is ejected, but when the gradation m = 2, the first ink droplet is not ejected (that is, the nozzle is not used). A predetermined pixel density is obtained using the second and third ink droplets.

Accordingly, the lower part of Table 1 shows

[0043]

(Equation 6)

This value corresponds to the frequency of use of the nozzle.

[0045]

[Table 1]

As described above, the presence / absence of ink ejection f (m,
By defining n), unless a specific gradation level image alone is intensively recorded, a large number of ink droplets in a specific order are not used, and therefore only a specific nozzle is not driven many times. .

In the example shown in Table 1,

[0048]

(Equation 7)

Are 8 to 9. That is, since the maximum number N of ink drops is 16 in this embodiment,

[0050]

(Equation 8)

Is satisfied.

This

[0053]

(Equation 9)

This corresponds to the case where each nozzle is used most uniformly when the image level to be recorded appears on average.

Generally, the maximum number of ink droplets N is about 3 to 5 and is often used.

[0056]

(Equation 10)

The setting of only is effective enough to extend the life of frequently used nozzles.

Embodiment 2 FIG. 4 shows a second embodiment of the present invention. In this embodiment, the recording head 21 has 256 nozzles and has a density of 16 nozzles / mm. The recording head 21 has nozzles arranged in a horizontal direction in the drawing, and moves on a rail 24. The recording paper 22 is wound around a drum 23. The drum 23 is rotated by a motor (not shown).

Next, a description will be given of ink ejection control when printing is performed at five gradations using this apparatus.

First, the recording head 21 is positioned at the leftmost end of the drawing, Recording is performed by rotating the drum 23 once by using only 193 to 256 64 nozzles.

Next, the recording head 21 is moved to the right by 64 pixels, and the nozzle no. Recording is performed by rotating the drum 23 once using 128 nozzles 129 to 256. In this manner, the head is moved to the right by 64 pixels.
3 is rotated once, and recording is sequentially repeated to record the entire surface.

As a result, for example, the first pixel is the nozzle N
o. It is formed by four nozzles of 1, 65, 129, and 193, and recording of five gradations can be performed with 0 to 4 ink droplets.

In this embodiment, the presence or absence of ink ejection f (m, n) is determined according to the following Table 2 corresponding to the density level (gradation) of each pixel.

[0064]

[Table 2]

Also in this embodiment,

[0066]

[Equation 11]

It is still true that the above condition is satisfied. Here, the density (OD) for each gradation level was as shown in Table 3 below.

[0068]

[Table 3]

When a full-color image is actually recorded, the above-mentioned five gradations are insufficient, so it is preferable to use a known image gradation processing method such as a dither method or an error diffusion method.

As a result of this combination, the OD on the image is 0.5
In all cases where the number is 5 or less, the number of ink drops is 1 drop per pixel or 0 drop per pixel, and the frequency of use of the nozzle corresponding to gradation level 1 tends to increase.

Therefore, in order to reduce the frequency of use of the nozzle corresponding to the gradation level m = 1 (in this case, the nozzle corresponding to the first ink droplet), when n = 1,

[0072]

(Equation 12)

Is selected to be "2" which is a value lower than the average.

As described above, the frequency of one drop per pixel tends to be extremely high because the maximum number N of ink drops is 10
This is remarkable in the following cases.

Embodiment 3 In the third embodiment, the same apparatus and the same recording head as those of the first embodiment are used, and recording of 17 gradations is performed by using a different recording method.

FIG. 5 shows the recording method of the third embodiment and the first embodiment.
This shows the difference from the recording method.

When recording on recording paper, first, 1
Printing is performed while moving the carriage using 16 nozzles 13 to 128. At this time, printing is performed using 0, 1, or 2 ink droplets per pixel according to the image density.

Next, the recording paper is fed upward by 16 pixels, and N
o. Recording is performed using 97 to 128 nozzles. As a result, no. The nozzles of Nos. 97 to 112 correspond to the previous Nos. 113
No. to 128 nozzles. The pixel portions of Nos. 1 to 16 are recorded. Nozzles 113 to 128 are newly N
o. 17 to 32 pixels will be recorded.

Therefore, No. Pixels 1 to 16 are recorded with 0 to 4 ink droplets per pixel.

Next, the recording paper is fed upward by 16 pixels again. Recording is performed using nozzles 81 to 128.
When such recording is sequentially repeated, when the eighth recording is completed, No. Pixels 1 to 16 have been recorded with 0 to 16 drops of ink, and recording of 17 gradations is obtained.
By repeating the recording in the same manner as above from the ninth time onward, an image of 17 gradations is obtained over the entire screen.

Here, the presence or absence of ink ejection may be determined in the same manner as in the first embodiment, depending on the density gradation of each pixel.
Since the first ink droplet and the second ink droplet, the third ink droplet and the fourth ink droplet,..., The fifteenth ink droplet and the sixteenth ink droplet are ejected from the same nozzle, the distance between the ink droplets ejected from the same nozzle is reduced. There is no point in averaging with

In view of the fact that the use of as many nozzles as possible in printing the same pixel reduces image unevenness, the presence or absence of ink ejection is determined as shown in Table 4 below.

[0083]

[Table 4]

In Table 4, the portion described as sum refers to the droplet discharged from the same nozzle.

[0085]

(Equation 13)

[0086] is added. Therefore, by determining the presence or absence of ink ejection according to Table 4, each nozzle can be used on average.

When one nozzle discharges one drop of ink per pixel, the timing of discharging two drops is unified to the earlier timing. Therefore, even when the density level differs between adjacent pixels, two ink droplets are not continuously ejected except in the high-density region (m ≦ 8), and are more stably ejected. Good image uniformity and a beautiful image can be obtained.

Embodiment 4 FIG. 6 is an external view showing an ink jet recording apparatus according to a fourth embodiment of the present invention.

In this embodiment, the recording paper 32 as a recording material is wound around a drum 34 and a driving device 36
Rotates in the main scanning direction. The recording head 101 is set so that its nozzle row is slightly inclined with respect to the main scanning direction formed by the rotation of the recording paper 32 (that is,
(Not parallel).

When a full-color image is recorded, three (yellow, magenta, cyan) to four (black addition) recording heads are used (not shown). To perform recording.

The recording head 101 performs recording while moving from left to right in the sub-scanning direction by a head driving device (not shown).

FIG. 7 shows the relative positional relationship between the recording paper 32 and the nozzle rows included in the recording head 101. In the figure, a-17 to a + 2 on the left side of the figure indicate pixel numbers in the main scanning direction on the recording paper. The vertical lines b + 1 to b + 4 indicate main scanning lines formed by the rotation of the drum 34.

In the present embodiment, the recording head 101 has 20 nozzles, and ink droplets land on four scanning lines (more precisely, on and around the scanning lines) by one rotation of the drum 34. Let it. In other words, the twenty nozzles provided linearly on the recording head 101 are arranged so as to be oblique to the main scanning direction, and the ink landing area covered by the ink ejection is four. It is on and around the main scanning line.

As described above, since the nozzle rows of the recording head are arranged at a slight angle to the main scanning line,
Pitch P _N between the actual nozzle pixel pitch P _P than about 2
It is about% longer. However, since the recording paper moves by one pixel pitch in the direction of the arrow each time the recording head is repeatedly driven, the nozzle pitch in the main scanning direction coincides with the pixel pitch.

[0095] 10kHz frequency of repetitive driving of the recording head as an example, when a 1mm per 16 pixel density, the pitch P _P of the pixel is 62.5 .mu.m, the pitch P _N of the nozzles becomes 63.7Myuemu. Further, the speed of the recording paper is 0.625 m / sec.

In this embodiment, five ink droplets are ejected per pixel in the highest density portion. Therefore, 5
It is possible to perform six-step gradation recording of shots, four shots, three shots, two shots, one shot, and zero shots.

The process of performing such six-step gradation recording will be described in detail below.

First, the nozzle numbers 1-1 and 1 shown in FIG.
-2, 1-3, 1-4, 1-5, etc. will be described. In this nozzle number (xy), x indicates which main scanning line corresponds to the pixel. That is, x = 1 corresponds to a nozzle for forming a pixel on the main scanning line b + 1, and x = 2 corresponds to a nozzle for forming a pixel on the main scanning line b + 2 (hereinafter, omitted).

In the nozzle numbers (xy), y represents a nozzle used when ejecting ink droplets of “y” (in this embodiment, y ≦ 5). It does not indicate the order of ejection. For example, the main scanning line b +
In order to land three ink droplets at the position of the pixel number a-1 on the first ink droplet, the first ink droplet is ejected from the nozzle 1-3, and then the recording paper is moved in the direction of the arrow. Is moved by one pixel pitch to eject the second ink droplet from the nozzle 1-1, and further, the recording paper is moved by one pixel pitch in the direction of the arrow to cause the third ejection from the nozzle 1-2. The ink droplets of the eyes are ejected. In this way, ink landing as shown in FIG. 8C is performed.

In order to eject five ink droplets as shown in FIG. 8E, first, the first ink droplet is ejected from the nozzle 1-5, and then the recording paper is moved. Each time, ink is ejected in the order of nozzles 1-3, 1-1, 1-2 and 1-4.

By performing the above-described ink ejection control and moving the recording head 101 in the sub-scanning direction, an image is recorded while being spread in a direction perpendicular to the main scanning direction.
It is possible to prevent a gap from being formed between scanning lines even in a high density portion.

In FIG. 8, for the sake of explanation, the landing positions are described as being arranged in a straight line, but as is already known, an ink jet recording head having a plurality of nozzles must be driven in a time-division manner. In this case, it is possible to extend the landing position in the vertical direction by shifting the driving timing between the adjacent nozzles.

The pattern of the ink droplets to be overprinted is not limited to that of the present embodiment. For example, in the case of only two shots, it is possible to control so that the ink is ejected from the nozzles at both ends.

Furthermore, if the design is made in consideration of the timing of the time-division driving, the nozzle pitch may be slightly changed from that of the present embodiment, and the angle between the nozzle row and the main scanning line may be changed accordingly. it can.

In this embodiment, the presence or absence of ink ejection f (m, n) is determined as shown in Table 5 below in accordance with the density gradation of each pixel.

[0106]

[Table 5]

Here, n in Table 5 corresponds to the nozzle number (xn) shown in FIG.

By determining the presence or absence of ink ejection as described above, each nozzle is driven on average. Further, the dot of each pixel does not greatly deviate from the center of the pixel, and the sharpness of the image is improved.

(Others) It should be noted that the present invention includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for discharging ink, particularly in an ink jet recording system. An excellent effect is obtained in a recording head and a recording apparatus of a type in which the state of ink is changed by the thermal energy. This is because according to such a method, it is possible to achieve higher density and higher definition of 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 is a so-called on-demand type,
It can be applied to any type of continuous type, but especially in the case of on-demand type, it can be applied to the sheet holding liquid (ink) or the electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding the nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. As a result, the liquid (ink)
This is effective because air bubbles can be formed inside. The liquid (ink) is ejected through an ejection opening (ejection port) through the process of 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. US Pat. No. 4,463,335 discloses a pulse-shaped drive signal.
No. 9 and No. 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 the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned respective specifications, U.S. Pat. No. 4,558,333 and U.S. Pat.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration having a discharge section having a common slit as a discharge opening for a plurality of electrothermal transducers, and an aperture for absorbing pressure waves of thermal energy. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration in which is provided corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

In addition, even in the case of the serial type as described above, the recording head fixed to the apparatus main body or the electric connection with the apparatus main body or the ink from the apparatus main body is attached to 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 provided integrally with the recording head itself is used.

It is preferable to add ejection recovery means for the recording head, preliminary auxiliary means, and the like as the configuration of the recording apparatus of the present invention since the effects of the present invention can be further stabilized. To be more specific, capping means for the print head, cleaning means, pressurizing or suction means, an electrothermal transducer or a heat generating element for generating thermal energy for discharging ink droplets necessary for printing. Preheating means for performing preheating using a different heating element or a combination thereof may be used, and predischarge means for performing discharge different from recording.

Further, the types and the number of recording heads to be mounted are, for example, not only those provided for one color ink but also plural inks having different recording colors and densities. A plurality may be provided. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, but may be any of integrally forming a printing head or a combination of a plurality of printing heads. The present invention is also very effective for an apparatus provided with at least one of the recording modes of full color by color mixture.

[0115] The discharge port array is not limited to a single row, but may be configured in a plurality of rows (for example, a row is provided with 20 discharge ports and arranged in four rows).

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, even if the ink is solidified at room temperature or lower, it can be softened or liquefied at room temperature. Since it can be used in liquid form when recording is performed, it can be used in the present invention. Alternatively, in the ink jet system, in some cases, the temperature is adjusted so that the ink itself is kept within a range of 30 ° C. or more and 70 ° C. or less, and the temperature is controlled so that the viscosity of the ink is in a stable ejection range. 30 ° C in this case
An ink that is liquid at a temperature of 70 ° C. or lower can be used. In addition, the ink is liquefied for the first time by heating in order to positively prevent the temperature of the ink itself from rising due to thermal energy or to prevent the ink from evaporating by using the energy as the energy of the state change from the solid state to the liquid state of the ink. May be used. In any case, the application of heat energy causes the ink to be liquefied by the application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start solidifying when it reaches 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
JP-A-54-56847 or JP-A-60-7
It may be used for recording while being held as a liquid material or a solid material in concave portions or through holes of a porous sheet as described in JP-A-1260. In the present invention, it is most effective to execute the above-described method of causing film boiling for each ink.

In addition, the form of the ink jet recording apparatus according to the present invention is not limited to one used as an image output terminal of an information processing apparatus such as a computer, a copying apparatus combined with a reader or the like, and a facsimile having a transmission / reception function. It may be in the form of an apparatus.

[0118]

As described in the foregoing, according to the present invention, multiple
Number of main scans forms one pixel with multiple ink droplets
That is, a plurality of ink liquids are
Drops land at approximately the same location, improving fixability
A special effect can be obtained. Further , according to the present invention, the frequency of use of each nozzle is averaged when obtaining a high-speed and uniform image using a recording head having a plurality of ink ejection ports (nozzles). It is possible to prevent the life of the recording head from being shortened due to excessive use of the nozzles.

Further, according to the present invention, a change in the gradation of the image caused by the use history of the nozzle, a change in the gradation caused by the non-uniform temperature rise of the recording head, the unevenness of the image density, etc. Can be suppressed, and a good image can be stably obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a control system of the present embodiment.

FIG. 3 is an explanatory diagram showing a recording method according to an embodiment of the present invention.

FIG. 4 is a perspective view of an inkjet recording apparatus according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram of another embodiment of the present invention.

FIG. 6 is a perspective view of an inkjet recording apparatus according to another embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a recording method of the apparatus shown in FIG.

FIG. 8 is an explanatory diagram showing a recording method of the apparatus shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 2 Recording paper 3 Platen 4 Carriage 5A, 5B Guide shaft 6 Ink supply tube

Claims (3)

(57) [Claims] 1. A multiple ink droplets from a plurality of ink discharge ports
Oh in the ink-jet recording method for forming a gradation image by land at substantially the same position on the recording material by several main scanning
It, according to a predetermined ink discharge ports driven rules for each gradation as the frequency of use of the ink discharge ports to be used to obtain each gray scale is substantially uniform, and performs image formation Ink jet recording method. 2. A multiple ink droplets from a plurality of ink discharge ports
An ink jet recording method in which a gradation image is formed by landing at substantially the same position on a recording material by several main scans , wherein each ink ejection port is driven to land up to N ink droplets. In this case, the presence or absence of ink ejection for the n-th (n = 1 to N) ink droplet is predetermined for each ink ejection port, and the frequency of use of each ejection port during image formation. Is not more than a predetermined value. 3. 0 to ink jet recording method for forming a gradation image by land at substantially the same position on the recording material by a plurality of main scanning of the ink droplets N droplets from a plurality of ink discharge ports met Te, in determining the presence or absence of ink droplets required to form a gray level of each pixel m (0 ≦ m ≦ n) , the ink liquid of the n-th (n = 1 to n) For the droplet, f (m, n) = 1 when the droplet is ejected f (m, n) = 0 when the droplet is not ejected If n (n = 1 to N), 1) An ink jet recording method, wherein the use or non-use of each ink ejection port is determined so that