JPH04358859A - Recorder and recording method - Google Patents

Abstract

PURPOSE:To reduce the influences of irregularily, streaks, etc., by a method wherein a plurality of dots constituting each picture element are formed respectively with different recording elements by a first relative transfer a plurality of times, and are formed at respective different positions of the picture element. CONSTITUTION:A recording head 1 equipped with a plurality of recording elements is used. In order to form dots on a medium 2 to be recorded (recording paper) with a plurality of the recording elements, a first relative transfer of the recording paper 2 and the recording head 1 and a second relative transfer of the recording paper 2 and the recording head 1 are carried out. Then, recording is carried out by a combination of picture elements composed of dots. A picture element is composed of a plurality of dots formed of respective different recording elements to be formed by especially each of the first relative transfer a plurality of times, and a plurality of those dots are formed at different positions, of the picture element. Thereby, dispersion among recording elements of a recording characteristic is reduced, and streaks and irregularity are hardly produced.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a recording device used as an information output device in a word processor, a copier, a facsimile machine, etc., and also as a printer for outputting information from a host device when connected to the device, and its recording device. In particular, the present invention relates to a recording apparatus using a so-called serial type recording head and a recording method thereof.

0002

[Prior Art] In a recording device, characters, images, etc. recorded on a recording medium such as recording paper are generally digital images formed by a set of pixels to which density data is individually assigned. be. Each pixel is formed by a dot formed on the recording medium by the recording head. As recording head methods for forming these dots, thermal transfer methods and inkjet methods are widely known.
It has many advantages such as enabling high-speed recording, and has been widely used in recent years.

[0003] As described above, when expressing the gradation of a recorded image in a recording device, density data is given to each pixel according to this gradation data, and each pixel has a dot configuration according to the density data. determined. Broadly speaking, there are two types of dot configurations: one is a configuration in which the number of dots corresponding to the density data is overlapped, and the second is a configuration in which the number of dots in accordance with the density data is developed in a predetermined pattern. .

The former dot configuration is relatively commonly used in inkjet recording apparatuses. One of the recording methods for realizing this dot configuration is to form a single dot by landing a plurality of ink droplets ejected from a single ink ejection port at substantially the same location on a recording medium. A so-called multi-droplet method is known in which the density of a pixel is expressed by changing the number of ink droplets landed.

[0005] Such a multi-droplet method is
This is an effective method because it is relatively difficult for the inkjet recording method to significantly modulate the size of individual ink droplets, and it is particularly effective because it uses thermal energy to generate air bubbles in the ink. This is effective in an inkjet recording method in which ink is ejected accordingly. Further, this method using thermal energy is effective as a method for obtaining images with high density and high gradation.

[0006]

[Problems to be Solved by the Invention] However, in the conventional multi-droplet method described above, one pixel is formed by a plurality of ink droplets ejected from one ejection port, so the amount of ink droplets ejected is If there are variations among the ejection ports, or if there are ejection ports that eject poorly or do not eject, there is a problem that the density of the image, which should be uniform, becomes uneven and streaks occur.

[0007] This problem is equally applicable to the latter dot configuration, that is, when a pixel is composed of dots developed in a predetermined pattern, although there are differences in degree.

In order to avoid these problems, conventional recording heads must be manufactured with great precision in order to minimize variations in the amount of ink droplets ejected between the ejection ports. The cost of the head increases,
This may lead to adverse effects such as poor manufacturing yield.

In addition, as a method for eliminating density unevenness in recording density using software, image processing such as error diffusion method is used to change the number of ejected ink droplets so as to cancel out the dispersion in the amount of ink droplets ejected between the ejection ports. There are known ways to do this. However, incorporating such image processing circuitry often increases the cost of the system. Furthermore, even if such an image processing method is used, the number of ejected ink droplets may need to be readjusted if, for example, the variation in the amount of ink droplets ejected between the ejection ports changes over time. However, the problem of reduced maintainability cannot be solved.

The present invention has been made to solve the above-mentioned problems, and its purpose is to configure one pixel with dots each formed by a plurality of recording elements, thereby achieving the following: It is an object of the present invention to provide a recording device and a recording method that reduce variations in recording characteristics between recording elements and are less likely to cause streaks or unevenness.

[0011]

[Means for Solving the Problems] To this end, in the present invention,
A first relative movement between the recording medium and the recording head for forming dots on the recording medium by the plurality of recording elements using a recording head equipped with a plurality of recording elements; and a first relative movement between the recording medium and the recording head, and the recording medium. and a second relative movement between the recording head and the recording head, and performs recording using a set of pixels constituted by the dots, the recording method comprising: a second relative movement between the recording head and the recording head; The pixel is formed by a plurality of dots formed by a recording element, and the plurality of dots are formed at different positions in the pixel.

[0012] Further, in order to form dots on the recording medium by the plurality of recording elements using a recording head equipped with a plurality of recording elements, a first relative movement between the recording medium and the recording head; , a second relative movement between the recording medium and the recording head, and in a recording apparatus for performing recording by a set of pixels constituted by the dots, the first relative movement is performed a plurality of times. The first pixel is formed by a plurality of dots formed by different recording elements, and the plurality of dots are formed at different positions in the pixel.
and a control means for controlling the second relative movement.

[0013]

[Operation] According to the above configuration, the plurality of dots constituting each pixel are formed by different recording elements and at different positions in the pixel by each of the plurality of first relative movements. .

[0014]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic perspective view showing the main parts of an inkjet recording apparatus according to an embodiment of the present invention. In FIG. 1, a recording head 1 is provided with, for example, 32 ejection ports arranged in the conveyance direction (hereinafter also referred to as the sub-scanning direction) of the recording paper 2 at intervals of 79.4 μm, and a The ink path communicating with this is equipped with a heater for generating thermal energy used for ejection. The heater generates heat in response to electric pulses applied in accordance with drive data, which causes film boiling in the ink, and as bubbles are generated by this film boiling, ink droplets are ejected from the ejection port. Ru. In this example, the driving frequency of the heater, that is, the ejection frequency is 2 kHz.

The carriage 4 carries the recording head 1, and has two guide shafts 5A that are slidably engaged with each other at a part of the carriage 4.
, 5B. The carriage 4 is moved by, for example, a belt stretched by a pulley attached to a part of the carriage 4, and this belt is moved by the rotation of a motor via the pulley, but the illustration is Omitted. The ink tube 6 is connected to the recording head 1, so that ink can be supplied to the recording head 1 from an ink tank (not shown). The flexible cable 7 is connected to the recording head 1, and thereby transmits drive signals and control signals based on recording data from the host device or the control unit of this device to a head drive circuit (head driver) provided in a part of the flexible cable 7. be able to. Both the ink supply tube 6 and the flexible cable 7 are made of flexible members so that they can follow the movement of the carriage 4.

The platen roller 3 has its longitudinal direction extending parallel to the guide shafts 5A and 5B, and is rotated by a paper feed motor (not shown) to convey the recording paper 2 as a recording medium, and to rotate the recording paper 2 as a recording medium. Regulate the recording surface. In the above configuration, as the carriage 4 moves, the recording head 1 performs recording by ejecting ink onto the recording surface of the recording paper 2, that is, the portion facing the ejection ports.

FIG. 2 is a block diagram showing the control configuration of the ink jet recording apparatus shown in FIG. 1. As shown in FIG.

The main controller 100 is composed of a CPU, etc., and converts the image data sent from the host computer 200 into pixel data to which gradation data has been added, and stores this in the frame memory 100M. The main controller 100 also has a frame memory 10.
The gradation data for each pixel stored in 0M is supplied to the driver controller 110 at a predetermined timing. The driver controller 110 converts the supplied gradation data into
For example, as described later in FIG.
Drive data (indicating on/off of the heater in the print head 1) corresponding to the scan number (indicates the number of main scans) and scan number (indicates the number of main scans) data) and stores it in the drive data RAM 110M. In response to a control signal from the main controller 100, the driver controller 110 reads the drive data stored in the drive data RAM 110M with reference to the ejection port number and scan number, supplies this to the head driver 110D, and controls the drive of the head driver 110D. Control timing.

In the above configuration, the main controller 100 controls ink ejection by the recording head 1, rotation of the carriage feed motor 104, and rotation of the paper feed motor 102 via the driver controller 110, motor driver 104D, and motor driver 102D, respectively. do. As a result, characters, images, etc. corresponding to the image data are recorded on the recording paper 2.

Note that in the above configuration, the driver controller 110 converts the gradation data into drive data, but the main controller 100 may also perform this. In this case, the drive data can be stored in the frame memory 100M, thereby allowing the RAM 110M to be omitted.

Several embodiments of the present invention carried out in the above-described inkjet recording apparatus will be described below.

(Embodiment 1) The principle of this embodiment will be explained below.

In this embodiment, the number of ejection ports of the print head is N.
(N is an integer of 2 or more), p (μm) is the pixel pitch in the sub-scanning direction (transport direction) of the recording medium, q (μm) is the ejection port pitch, and the relationship between the recording head and the recording medium for each scan. The amount of relative movement in the sub-scanning direction, that is, in this example,
The paper feed amount of the recording paper is s (μm), and the maximum number of ink droplets per pixel per scan, that is, the maximum number of ink droplets ejected from one ejection port for one pixel in one scan is K (K is an integer greater than or equal to 1), and the maximum number of ink droplets to be ejected per pixel, that is, the maximum gradation - 1, is m (m is 2
(an integer greater than or equal to)

[0025]

[Math. 1] {(N-1)q+p}/s≧2
(1)

00
26]

[Math. 2] NKp/s≧m

(2)

[0027]

[Equation 3] Both s/q and p/s are non-integers
This is a recording method characterized by (3).

The condition expressed by the above equation (1) is that all the pixels constituting the recorded image are formed by ejecting ink from different ejection ports by scanning the print head multiple times (twice or more). It shows the conditions for being composed of dots. In other words, the number of times that the ejection port array of the recording head that moves by the movement amount s moves by the length of the ejection port array (N-1)q plus the pixel width p is {(N-1)
q+p}/s, so if there are a plurality of these (two or more), each pixel will be scanned multiple times, and thereby each pixel can be composed of dots formed by ejection from different ejection ports.

The condition expressed by equation (2) is that the number of ink droplets that can be ejected into one pixel is equal to or larger than the value m, which is the value of the maximum gradation set in the device minus 1. The conditions are shown below. This condition can be obtained as follows. That is, when the recording head moves by s, the number of pixels that are overlapped and scanned in the width of this movement amount s is s/p, and therefore the total maximum number of dots to be printed on pixels within this width is ( s/p)・m. On the other hand, in the overlapping scan with the width s, each of the N ejection ports arranged in the print head can eject, so the total number of ink droplets that can be ejected into pixels within this width is NK. Therefore, the condition for obtaining the maximum gradation of −1 in each pixel is (s/p)·m≦NK.

The condition expressed by equation (3) is that ink droplets ejected from a pixel may not be ejected to the same location on the recording paper, that is, there are pixels in which dots are formed with deviations. It shows the conditions for doing so.

Here, if s=qp and q=bp, the above equations (1) to (3) can be expressed as follows.

[0032]

[Formula 4] {(N-1)b+1}/a≧2
(1)′

0
033]

[Mathematical 5] NK/a≧m

(2)'

[0034]

[Equation 6] Both a/b and b/a are non-integers
(3)' At this time, [{(N-1)b+1}/a]=h ([] is the quotient {
(N-1)b+1}/a), the number of duplicate scans to form one pixel is expressed as h or h+1 ({N-1)b+1}/a).
1) If b+1}/a is divisible, the number of scans forming one pixel is only h). Therefore, if the configuration of this embodiment is adopted, one pixel will be scanned h or h+1 times (
h or h+
Recording is performed by ejecting from one ejection port.

As a result, for example, if it is assumed that the variation in the amount of ink droplets ejected between the ejection ports is normally distributed with the standard deviation σ, when one pixel is formed with different h or h+1 ejection ports, Pixel-to-pixel variation in ink amount per pixel is

[0036]

[Outside 1]

It decreases to . Variations in the amount of ink between pixels are recognized as variations in pixel density, but in order for the image to appear clear, the variation in pixel density does not need to be zero, but only needs to be small to a certain extent, so according to this embodiment, A clear image with less unevenness can be obtained compared to the conventional example.

It is desirable that the value of h be as large as possible in order to reduce variations between pixels, and according to studies by the present inventors, even with h=2, a sufficiently clear image can be obtained compared to the conventional recording method. , it is known that an extremely clear image can be obtained when h=3 or more.

In addition, in the configuration of this embodiment, the maximum number of ink droplets that can be injected into one pixel is (h+1)K or hK, but as described above, in order to record m+1 gradations, one pixel The number of ink drops that should be applied per hit is 0~
It is m. Therefore, in this example, from equation (2), NK
If p/s>m, that is, hK>m, then 1
Since more ink droplets can be ejected per pixel than the number of ink droplets that should be ejected per pixel, even if there is an ejection port with ejection failure or other ejection failure, it is possible to compensate for this with other ejection ports and perform recording. As a result, image deterioration such as streaks can be prevented.

Further, according to studies conducted by the present inventors, it has been found that when forming a plurality of dots in one pixel, a high image density can be obtained by shifting the dots from each other and overlapping them. Therefore, in this embodiment, a plurality of dots can be shifted with a simple configuration by making the relative movement amount s and the ejection port pitch q both non-integer multiples of each other.

[0041] Hereinafter, recording by the above-described recording method using the above-described apparatus will be explained, taking as an example the case where three gradations are recorded at a pixel pitch of 63.5 μm. That is, recording is performed by changing the number of ink droplets ejected per pixel in a range of 0 to 2.

FIGS. 3 and 4 are a conceptual diagram and a schematic diagram, respectively, for explaining the recording method of this embodiment.
4 shows how the recording head 1 performs recording by moving by the paper feed amount s for each scan, and FIG. This figure schematically shows how dots within each pixel are formed by shifting them by appropriately determining the dots for each pixel. Although only one line in the sub-scanning direction is shown in FIG. 4, it goes without saying that the same applies to the other lines. In FIG. 3, the recording head 1 is schematically shown, and for convenience of explanation, it is assumed that four ejection ports are arranged at equal intervals (q) in the vertical direction of the figure. For convenience, in the figure, the discharge ports are numbered from the top to the bottom of the discharge port array. 1, 2, 3, 4. Furthermore, the description will be made assuming that the number of ink droplets ejected into one pixel in one scan is 1 (K=1).

[0043] When recording on recording paper, firstly, No. 2
Recording is performed while moving the carriage (first scan) using only the four ejection ports. As a result, No. 1 from above the recording paper. 1 to 3 pixels will be recorded with 0 or 1 ink drop. Here, it is assumed that a dot formed at the boundary of a pixel is included in the pixel below it (the same applies in the following description). Next, print the recording paper for 1.5 pixels (a=1.5
) upward (in the figure, for convenience, the head is shown to have moved relatively downward), No. Recording is performed by the second scan using ejection ports 1 to 4. As a result, the first
And by the second scan, No. Pixels 1 and 2 are 1
It is recorded with a number of ink droplets of 0 to 2 per pixel, and No. 3
, 4, and 5 are recorded with 0 to 1 ink droplet. Next, feed the recording paper upward by 1.5 pixels again N
o. Recording is performed by the third scan using ejection ports 1 to 4. By sequentially repeating such recording, Figure 4
As is clear from the above, each pixel can form up to 2 to 3 dots. For this reason, if one dot is omitted depending on the recording data in a pixel where a maximum of three dots can be formed, m=2 can be set for each pixel, and an image with three gradations can be obtained.

[0044] In the image obtained in this way, one pixel is formed by ink droplets ejected from a plurality of ejection ports, so variations in the amount of ink droplets from each ejection port are averaged, and streaks and unevenness are eliminated. This results in an unobtrusive image. Further, when two or more ink droplets are ejected into one pixel, the landing positions of each ink droplet are shifted, so each pixel is sufficiently covered with dots, and high image density can be obtained.

[0045] When various images were recorded using the above recording method, extremely clear images with no streaks or unevenness were obtained compared to the conventional recording of one pixel with multiple ink droplets ejected from the same ejection port. Obtained.

Furthermore, in this embodiment, the maximum number of dots per pixel is 2, whereas the pixels that can be recorded with 0 to 3 ink droplets (for example, pixels No. 4 and 5 in FIG. 4) are In such a pixel, one ejection port is not required. Specifically, as can be seen by examining FIG. 4 in detail, No. 2 or No. Either one of the No. 3 ejection ports may be defective. As a result, if, for example, it is known at the time of manufacturing a printing device that there is an ejection port with ejection failure, that information is written in the memory (ROM or RAM) of the printing device, and the ejection port used for ejection is controlled via the control unit. You can also choose. In addition, after manufacturing a recording device, if an ejection failure such as non-ejection occurs at a certain ejection port while the device is in use, a service person or user can write that information into the RAM of the recording device and use it for other ejection ports. It can also be compensated by the outlet.

(Modification 1 of Embodiment 1) FIG. 5 is a schematic perspective view of an inkjet recording apparatus according to a modification of the first embodiment.

The recording head 1 has five ejection ports arranged in the horizontal direction in the figure at a density of 16 ejection ports/mm, and is mounted on a carriage 4 along a rail with which it is slidably engaged. Can be moved. The recording paper 2 is wound around a drum 3, and the drum 3 is rotated by a motor (not shown). According to this configuration, main scanning is performed by rotation of the drum. 16 pixels/m using this device
An example of recording four gradations at a density of m will be described below.

FIG. 6 is a schematic diagram for explaining the recording method according to this modification.

First, the recording head is positioned at the right end in FIG. 5, and the ejection port no. Recording is performed by rotating the drum once using only two ejection ports 4 and 5. Next, turn the head to the left 5/
Move by 3 pixels (a=5/3) and move the discharge port No. Recording is performed by rotating the drum once using three ejection ports 3 to 5. In this way, for each scan, the recording head is moved to the left by 5/3 pixels, and then the drum is rotated once to perform recording, which is sequentially repeated to record the entire surface. As a result, for example, No.
．． The pixel number 1 is the ejection port number. The ink droplets are formed by three ink droplets 1, 3, and 4, and four gradation recording can be performed with the number of ink droplets from 0 to 3.

When various images were recorded using the above recording method, extremely clear images without streaks or unevenness were obtained.

(Modification 2 of Example 1) Using the same apparatus and recording head as in Example 1, that is, the recording head with 4 ejection ports and ejection port pitch q = 79.4 μm, a different printing method from Example 1 was used. pixel pitch p=79.4μm using
A case in which five gradations are recorded will be described below.

FIG. 7 is a schematic diagram for explaining the recording method according to this modification.

[0054] When recording on recording paper, firstly, No. 2-4
Recording is performed while moving the carriage using the three ejection ports. At this time, recording is performed by ejecting 0, 1, or 2 ink droplets per pixel depending on the image density. That is, in this example, a maximum of two ink droplets can be injected into one pixel in one scan (K=2). Next, feed the recording paper upwards by 7/4 pixels (a = 7/4)
．． Recording is performed using ejection ports 1 to 4. Next, feed the recording paper upwards again by 7/4 pixels. Recording is performed using ejection ports 1 to 4. Such recording is sequentially repeated, and each pixel is recorded with 0 to 4 ink droplets to obtain a 5-tone image. At this time, as can be seen from the figure, for example, pixel No.
3 or 4, it is possible to shoot 0 to 6 ink drops. In such a pixel, any of the ink droplets is unnecessary, and ejection is controlled so that the number of ink droplets is 0 to 4 according to the recording data. Moreover, according to this example, No. 1
and No. It can be seen that even if any one of the four ejection ports fails to eject, a five-tone image can be obtained.

In this embodiment, the maximum number of ink droplets ejected per pixel per scan is 2, but this can also be increased to 3 or more, and thereby an image with an even higher number of gradations can be obtained. .

(Modification 3 of Example 1) The same apparatus as Example 1 except that a recording head with 67 ejection openings and an ejection opening pitch q of 70.6 μm was used, and the paper feed amount s was 1063.6 μm. was used to record five gradations at a pixel pitch of p=63.5 μm. A conceptual diagram of the recording method according to this example is shown in FIG.

When various images were recorded using this recording method, extremely clear images with no streaks or unevenness were similarly obtained.

(Embodiment 2) In the above embodiment 1 and its modifications, the number of dots to be recorded per pixel is m, whereas the number of dots that can be formed is hK, and hK≧
It was m. However, if there is no need to consider compensation for ejection ports with ejection failure, it is more efficient to form dots without excess or deficiency. Therefore, the condition for this is that NK/a=m in the above equation (2)'.

[0059] Furthermore, when paper feeding is performed, for example, the bottom edge of the image recorded before the paper feeding must match the top edge of the image recorded after the paper feeding. Discrepancies may occur due to positional deviations such as errors. In such a case, by setting (Nq+p)/s to a non-integer, the dot pattern within each pixel can be made non-uniform, and the influence of this error etc. can be reduced.

Embodiment 2 of the present invention will be described below, taking as an example the case where recording of four gradations is performed at a pixel pitch p=63.5 μm using the apparatus shown in FIGS. 1 and 2. That is, recording is performed by changing the number of ink droplets per pixel in a range of 0 to 3.

FIGS. 9 and 10 are conceptual diagrams and schematic diagrams for explaining the recording method of this embodiment. The recording head 1 has six ejection ports arranged in the vertical direction in the figure. In addition, the discharge port numbers are 1, 2, ..., 6 from the top of the diagram to the bottom.
shall be.

When recording on recording paper, first, in the first scan, No. Printing is performed using only two ejection ports 4 and 5 while moving the carriage. As a result, pixel N
o. A maximum of one ink droplet will be ejected into each of the areas 1 and 2. Next, in the second scan, the recording paper is scanned for two pixels (a=
2) Upward feed (in the diagram, for convenience, the recording head is shown to have moved relatively downward) No. Recording is performed using 4 to 6 ejection ports. As a result, pixel No. A maximum of two ink droplets are ejected into No. 1, and No. A maximum of one ink droplet will be ejected into pixels 2 to 4. Next, in the third scan, after feeding the recording paper upward by two pixels, No. Recording is performed using 2 to 6 ejection ports. As a result, pixel No. Up to 3 ink droplets can be placed in No. 1 and No. 1. 2,
There are a maximum of two ink droplets in the No. 3 pixel; A maximum of one ink droplet will be ejected into pixels 4 to 6. Furthermore, after feeding the recording paper upward by 2 pixels, No. Recording is performed using ejection ports 1 to 6, and in subsequent scans, each time the recording paper is moved upward by two pixels, No.
．． Recording using ejection ports 1 to 6 is sequentially repeated. As a result, the maximum number of dots that can be formed in each pixel is three, and a four-tone image is obtained. This maximum value is the same for all pixels, so that the ink droplets that can be ejected are used in just the right amount to form dots.

(Modification 1 of Example 2) FIG. 11 is a schematic diagram for explaining the recording method of this example. Further, this example is applied to a device similar to the device shown in FIG.

First, after the recording head is positioned at the rightmost end in FIG. 5, in the first scan, the ejection port No. Recording is performed by rotating the drum once using only two ejection ports 4 and 5. At this time, recording is performed by ejecting 0, 1, or 2 ink droplets per pixel depending on the image density (K=2). Next, after moving the print head to the left by 2.5 pixels (a=2.5), in the second scan, the ejection port No. 1-5 of 5
Recording is performed by ejecting a maximum of two ink droplets after the drum rotates once using three ejection ports. In this way, the recording head was moved to the left by 2.5 pixels, and then the drum was rotated once to perform recording, which was repeated sequentially to perform recording on the entire surface. As a result, for example, the first pixel has no. Printing is performed using a maximum of four ink droplets ejected from two ejection ports 1 and 4, making it possible to print in five gradations.

(Modification 2 of Embodiment 2) FIG. 12 is a conceptual diagram showing the recording operation when the recording method described in Embodiment 2 is applied to a recording head having 89 ejection openings and an ejection opening pitch of 706 μm. . In this example, the paper feed amount is 1412.9 μm.
Except for this, the same apparatus as in Example 2 was used to perform recording at a pixel pitch of 63.5 μm and 5 gradations.

When various images were recorded using the apparatus of this example, extremely clear images without streaks or unevenness were obtained.

(Example 3) In Examples 1 and 2 above, by appropriately setting the pixel pitch p, the ejection port pitch q, and the relative movement amount s, the dots of each pixel can be ejected differently in multiple scans. formed by ink droplets from the outlet,
Moreover, the conditions under which these dots are formed with deviations within a pixel have been explained.

In addition to the above conditions, in the third embodiment, the number of dots formed within a pixel uniquely corresponds to the pattern of these dots, each dot does not overlap, and within this pattern, This relates to conditions under which dots are uniformly arranged. By applying a recording method based on such conditions, it becomes easier to control the density and quality of a recorded image at the pixel level.

The conditions of this example will be explained below.

When the coordinate of the dot formed on the recording paper in the sub-scanning direction is x, the coordinate xij of the dot formed by the ink droplet ejected from the i-th ejection port during the j-th scan is If you choose appropriately,

[0071]

[Formula 7] xij=qi+sj=(bi+aj)p
(4).

Here, considering the condition that a plurality of dot patterns formed within one pixel are uniform, a,
b becomes a rational number. Therefore, b=β/α, a=η/ξ(α
and β, η and ξ are mutually prime natural numbers), and the above equation (4) can be expressed as

[0073]

[Math. 8]

It can be expressed as: Here, if the greatest common divisor of α and ξ is g, and the greatest common divisor of β and η is f, then equation (5) becomes

[0075]

[Math. 9]

[0076] Here, α′=α/g, ξ′=ξ
/g, β'=β/f, η'=η/f.

Here, since α and β are mutually prime, α' and β' are also mutually prime, and since ξ and η are mutually prime, ξ' and η' are also mutually prime. Also,
α′ and ξ′ are also relatively prime, and β′ and η′ are also relatively prime. From the above, β′ξ′ and α′η′ are also relatively prime. Therefore, depending on the natural numbers i and j, β′ξ′i+α′η′j can take on all integer values greater than or equal to a predetermined number. Therefore, the value of xij when taking this predetermined number can be determined as the coordinates of the endmost dot in the image.

By the way, it can be understood from equation (6) that the value of the integer part of xij/p indicates to which pixel the dot at the coordinates belongs. The value of this integer part is N
Then, there are on average gα'ξ'/f xij satisfying the range of Np or more (N+1) less than p within this width p. That is, gα′ξ′/f dots are formed at the Nth pixel. Here, if f≠1, then f and gα′=
Since α is relatively prime and h and ξ′ are also relatively prime, gα′ξ′
/f is not an integer. As a result, for example, the interval Np or more (
The number of xij that satisfies less than N+1)p and the interval (N+1)p
The number of xij satisfying the condition greater than or equal to (N+2)p is different. For example, q=(4/5)p, s=(8/5)p
When , from equation (4)

[0079]

[Math. 10]

Substituting natural numbers for i and j in equation (7), xij/p is in the range of 4M or more and less than 4M+1, 0,
0.8; takes two different values such as 4.0, 4.8, etc., but otherwise takes one different value such as 1.6; 2.4; 3.2; 5.6, etc. I only take it. In this way, f≠
If it is 1, the maximum number of dots that can be formed by pixels will differ. On the other hand, when f=1, the number of dots that can be printed in the section is always a constant value. Therefore, f must be 1 to equalize the number of dots that can be formed in each pixel. From this condition that f=1, it is possible to draw the conclusion that β and η are relatively prime (condition 1).

At this time, one pixel is composed of a maximum of gα'ξ' ink droplets ejected from different ejection ports.

Now, since f=1, if we rewrite equation (6), we get

[0083]

[Math. 11]

[0084]

Now, consider a case where two dots have the same coordinates. At this time,

[0086]

[Formula 12] xi+ i j− j = xij

(9). In other words, the dot indicated at the position xij was scanned Δj times before, and the coordinates of the dot ejected by the ejection port after Δi are the coordinates xi+i
Let it be equal to j− j. At this time, from equations (8) and (9),

[0087]

[Formula 13] βξ′(i+Δi)+α′η(j
−Δj)=βξ′i+α′ηj Therefore

[0088]

[Formula 14] βξ′Δi=α′ηΔj
(10
) Here, since βξ′ and α′η are relatively prime, the equation (10
), the minimum positive solution among (Δi, Δj) that satisfies

00
89]

[Math. 15]

[0090] That is, at this time, xij is
This is the same as the position of a dot formed by an ink droplet ejected from the ejection port α′η after i during the scan βξ′ times before j. Therefore, in order to prevent dots from being formed at the same point due to repeated scanning, it is only necessary that there be no ejection ports after α′η.
If the number N of ejection ports satisfies N≦α′η, no dots have the same coordinates.

On the other hand, N>1 is a condition for the recording head to have a plurality of ejection ports. The following formula holds from the above two conditions.

[0092]

[Formula 16] N=α′η>1 (condition 2)
(12)
Further, by scanning βξ′ times, each pixel can form a dot with ink droplets from a maximum of gα′ξ′ different ejection ports. Therefore, the conditions for this are

0093
]

[Formula 17] It can be expressed as gα′ξ′>1 (condition 3), βξ′>1 (condition 4) (13).

The condition of this embodiment is that the above conditions 1 to 4 are satisfied simultaneously.

[0095] α, β,
When ξ and η are determined, xij=(βξ′i+α′ηj)
p/gα′ξ′ is the distance between the pixel to which the dot at the position indicated by xij belongs and the adjacent pixel in the sub-scanning direction.

[0096]

[Formula 18] mod(βξ′i+α′ηj, g
α′ξ′) :gα′ξ′
−mod(βξ′i+α′ηj, gα′ξ′)


The position of the point that is internally divided into the ratio of (14) is shown. Here, mod(βξ′i+α′ηj, gα′ξ′
) indicates the remainder when (βξ′i+α′ηj) is divided by gα′ξ′. Now, when the image level of the pixel is k, that is, when the pixel is composed of ink droplets ejected from k different ejection ports, the selection method for i and j is

[0097]

[Outside 2]

There is a street. In this embodiment, as a method of selecting k sets of i and j from among these, a predetermined set Mk (k=1, 2,..., gα'
ξ′−1) is determined, and mod(βξ′i+α′ηj
, gα′ξ′)∈Mk. Here, Mk is a subset of k pieces extracted from {0, 1, . . . , gα′ξ′−1}. As mentioned above, Mk
By predetermining , and selecting (i, j) accordingly, when the image level is equal, that is, when the number of ink droplets applied to one pixel is equal, the dot arrangement pattern within the pixel will always be the same. Can be done.

The specific recording method of the third embodiment explained above will be explained below.

In this example, printing is performed using an inkjet printing apparatus similar to that shown in FIG. However, the number of ejection ports provided in the recording head 1 is nine, the ejection port pitch q is 84.67 μm, and the pixel pitch p is 63.5 μm. Therefore, q=4/3p, that is, b=4/3. In this example, description will be given assuming that four gradations are recorded. That is, recording is performed by changing the number of dots per pixel (hereinafter referred to as image level) in the range of 0 to 3.

FIGS. 13A and 13B are conceptual diagrams for explaining the recording method of this embodiment and schematic diagrams showing the recording results.

First, in the first scan, No. Scanning is performed so that the ejection port No. 7 passes through the highest point I00 of the pixel U00. Since the discharge port pitch q=(4/3)p, N
o. No. 8 ejection port is between I01 and I02, that is, pixel U
01, No. The ejection port 9 passes between I02 and I03, that is, the pixel U02. No. Since the ejection ports 1 to 6 do not pass through the points on the pixels of the recording paper 2, they are not used in the main scan.

Next, in the second scan, the recording paper 2 is sent upward by 3 pixels s=3p, that is, by a=3, that is, after the recording head 1 is sent downward by 3 pixels as seen from the recording paper 2. Make a record. Therefore, No. The discharge port of No. 5 is I00.
and I01 are divided internally at a ratio of 1:2 (within pixel U00), No.
．． No. 6 ejection ports are located at a point where I01 and I11 are internally divided at a ratio of 2:1 (within pixel U01). 7 discharge port is on I03 (pixel U03
), No. No. 8 discharge port is in pixel U04. Each of the nine ejection ports passes through the pixel U05. No for this scan
．． Discharge ports 1 to 4 are unused.

After the recording head 1 is further moved relatively downward by three pixels, a third scan is performed. In this manner, scanning is performed by relatively moving the recording head 1 by three pixels for each scan. When such a recording operation is repeated, each pixel is scanned repeatedly four times at maximum, but the ejection port passes over each pixel only three times.

For example, the ejection port passes through the pixel U00 during the first, second, and third scans. Pixel U01 has 1st, 2nd, 4th
During the scan, the ejection port passes through, and during the third scan, the recording head passes through, but the ejection port does not pass through. At the same time, the light passes through the pixel U02 during the first, third, and fourth scans, but does not pass during the second scan. In addition, the position of the ejection port that passes through each pixel three times is
There is one case where j and Iij+1 are divided internally at a ratio of 1:2, and a case where Iij and Iij+1 are internally divided at a ratio of 2:1.

[0106] The above is summarized as shown in Fig. 14. In this way, the number of scans and ejection port number for forming each of the three dots forming each pixel are uniquely determined. Therefore, the density data for each pixel is converted into drive data that corresponds to the number of scans and the ejection port number, and is stored in advance in the drive data RAM 110M shown in FIG. 2. The contents of this RAM are shown in FIG.

As shown in FIG. 15, drive data is stored at a position corresponding to the scan number and ejection port number. For example, No. 3 of the third scan. The drive data for No. 4 ejection port is 1.
It spans the second dot of the fourth pixel, and “
Data of "1" or "0" (ejection or non-ejection) is stored.

The setting of drive data according to the density (image level) of each pixel is performed as follows.

In FIG. 14, 1/3 and 2/3 of a pixel are points that internally divide the distance from the next pixel to 1:2 and 2:1, respectively. In the first scan, pixel U01 has No. No. 8 ejection port is No. 8 in the second scan. No. 6 discharge port is the fourth
No. in the scan. One discharge port corresponds to each other. Therefore, if ink droplets are ejected at the same time as this pixel passes during all three scans, the image level will be 3.
can be recorded. Similarly, if ink droplets are ejected in any two of the above three scans, image level 2 is recorded, and if ink droplets are ejected in any one of the three scans, image level 1 is recorded. can be recorded.

However, for example, at image level 1, in order to reduce image unevenness and make the image uniform, it is better to have the dots placed at the same position in every pixel in the pixel area Uij. is preferable. For example, U00,
When the image levels of U01, U02, ... are all 1, U00 has the first scan No. 7. In U01, No. 4 of the 4th scan. 1, U02, No. 3 of the third scan. 4, . . . (this is called method A), dots are always formed at the upper end of each pixel, and a uniform image is obtained. On the other hand, if dots are formed at pixels U00, U01, and U02 in the first scan to record image level 1, the image level will be 1 for each pixel, but at pixel U00, the upper edge Point I00, pixel U
In pixel 01, a dot is formed at a point where I01 and I02 are internally divided at a ratio of 1:2, and in pixel U02, a dot is formed at a point where I02 and I03 are internally divided at a ratio of 2:1 (closer to U03 in the pixel). When such recording is performed, even if each pixel has the same image level, the dot spacing may become uneven and a uniform image may not be obtained.

Note that in order to form a uniform image of image level 1, it is of course possible to select other positions than the upper end of the pixel as described above. For example, in order to always select a point that divides the distance between the next pixel and the next pixel at a ratio of 1:2,
At pixel U00, the second scan No. 5. In pixel U01, No. 1 of the first scan. 8, pixel U02 has No. 4 scan. 2. It may be the position of a dot formed by points (this is referred to as method B).

[0112] In this embodiment, the discharge port pitch q=(
4/3) p (b = 4/3), relative movement amount (paper feed amount) s
= 3p (a = 3), α = 3, β = 4, ξ = 1, η
=3, g=1, therefore α'=3, ξ'=1. At this time, β and η are relatively prime, and α′η=αη/g
=1 (≧2), which matches the number N of discharge ports used. Furthermore, gα′ξ′=αξ=3 and βξ′=βξ=4 also hold true. In addition, in the case of method A described above, mod (
The value of βξ′i+α′ηj, gα′ξ′) is mod(4i
+3j,3)=mod(4×7+3×1,3)=mod
(4×1+3×4)=mod(4×4+3×3,3)=
...=1.

[0113] That is, set M1 = {1} in advance, and m
Set (i, j) such that od(βξ′i+α′ηj, gα′ξ′)∈M1. The same applies to method B.

[0114] In this example, the relationship between q, s and p does not have to be strictly established, and an error is allowed, and the degree of error depends on the number of p at the edge of the image on the recording medium. This causes a landing error of about 1/2.

(Modification 1 of Example 3) FIG. 16 shows Example 3
It is a conceptual diagram concerning a modified example of.

In this example, pixel pitch p=(25.4/3
00) mm, discharge port pitch q=(5/3)p=(25.
8/180) mm, relative movement amount s = (199/15) p
It is. Pixel U0,0 indicates the upper leftmost pixel on the recording paper (shaded area in the figure). In addition, the number of discharge ports is 199.
It is individual.

[0117] First, during the first scan, No. Printing is performed by making one ejection port correspond to the upper corner of virtual pixel V0,317 (317 pixels above U0,0). Next, during the second scan, the recording head 1 is relatively moved in the sub-scanning direction by s=199p/15 to perform recording. For each pixel, the ejection port passes through 15 times out of a maximum of 25 overlapping scans. That is, 16-value gradation recording from 0 to 15 can be performed.

FIG. 17 shows this situation. In the figure, the horizontal axis shows scan numbers, and the vertical axis shows pixel columns. Here, for example, the pixel U0,0 has the No. 1 at the seventh scan. 144 discharge ports, No. 8 at the 8th scan. 136
, No. 9 at the time of the 9th scan. 128,..., No. at the 21st scan. A maximum of 15 dots can be formed by the ink droplets ejected at 32.

As mentioned above, the image level value is 1 or more and 14
In the following cases, it is possible to arbitrarily select which scan to perform ejection, but in this example, the scan number and ejection port number can be set to obtain the optimal density depending on the type of recording medium. Make a choice. This selection can be made by setting data in the drive data RAM shown in FIG. 2, as described above.

For example, consider the case where the image level value of U0,0 is 5. That is, when five dots are printed in the pixel, if paper with a relatively low ink bleeding rate is used, it is easier to obtain a high density by distributing the five dots as evenly as possible within the pixel. Therefore, the number of scan 9. 128, Scan 12 No. 104,
Scan 15 No. 80, Scan 18 No. 56
, Scan 21 No. 32 to form dots. On the other hand, when paper with a sufficiently large spread rate is used, excessive density can be prevented by keeping the dot occupancy as low as possible. Therefore, scan 17 No.
．． 64, Scan 18 No. 56, Scan 19 N
o. 48, Scan 20 No. 40, Scan 21 No. 32 to form dots.

As explained above, according to this example, (2
Using a recording head with an ejection opening pitch of 5.4/180) mm, it is possible to perform 16-value recording with pixels spaced at (25.4/300) mm, and density can be corrected depending on the type of recording medium. It has characteristics.

(Modification 2 of Embodiment 3) FIGS. 18, 19 and 20 are views of a modification of Embodiment 3.

In this example, pixel pitch p=(25.4/4
00) mm, discharge port pitch q=(3/2)p=(25.
4/200) mm, the relative movement amount s=(7/4)p, the number of ejection ports n=7, and the maximum number of dots per pixel is 4.

First, in the first scan, No. 6
The discharge port passes through the upper end of U0,0. As is clear from the figure, pixel U0,0 is No. 1 of the first scan. 6. Second scan No. 5. Third scan No. 4. No. 4 of the fourth scan. Dots corresponding to the image level are selected from the 4 dots formed by ejection from 3 and formed. Similarly, pixel U0,1 is No. 1 of the fifth scan.
2. No. 6 of the 6th scan. 1. No. of the first scan. 7
, second scan No. The dots are selected from the dots formed by ejection from No.6. Similarly, U0,2 is the No. of the third scan. 5. No. 4 of the 4th scan. 4. No. 5 of the 5th scan. 3. No. 6 of the 6th scan. The dots are selected from the dots formed by ejection from No. 2.

In the figure, PS indicated by diagonal lines surrounded by a vertical rectangle indicates a drive pulse at the ejection port. τ
is the maximum driving interval (driving cycle) of the recording head of this example, which is 400 μsec.

[0126] No. When ejecting ink droplets from the i ejection port during the j-th scan, the drive timing was determined as follows. That is, depending on the position where a dot is formed in each pixel, when the position is mod (6i + 7j, 4) = 3, it is at the start of the drive cycle, and when mod (6i + 7j, 4) = 0, it is 100 μs after the start of the drive cycle. , 200 μs after the start of the drive cycle when mod (6i+7j, 4)=1, and 300 μs after the start of the drive cycle when mod (6i+7j, 4)=2.

Furthermore, the positions of the dots were determined as follows depending on the image level at the pixel.

Image level 1: mod (6i+7j, 4)
= 3, Image level 2: mod (6i+7j, 4)∈{1,3}
The values of i and j such that Image level 3: mod (6i+7j, 4)∈{0, 1,
3}.

When the ejection timing and ejection port are selected as described above, the relative positions of dots within a pixel at each image level are as shown in FIG.

As described above, in the case of this embodiment, the dot arrangement is determined so that the occupation rate of the dot area is as high as possible at each image level. This is particularly effective in obtaining sufficient image density when a recording medium with a low bleeding rate is used. On the other hand, when the image level is low,
In order to achieve a lower density, the method for selecting i and j described above may be changed as follows.

[0131] When the image level is 2, mod (6i+7i,
4) Set (i, j) such that = {0, 3}. By making this change, the dot arrangement when the level is 2 becomes as shown in FIG. 20, and the area occupation rate of the dots decreases, making it easier to achieve low density.

In any case, it is possible to change the gradation expression depending on the type of recording medium and image processing.

(Modification 3 of Embodiment 3) FIG. 21 shows Embodiment 3
It is a conceptual diagram concerning a modified example of.

In this example, the ejection port pitch and pixel pitch are equal, p=q=63.5 μm, and the relative movement amount is s=(13/4
) p. Therefore, α=β=1, ξ=4, η=13,
g=1, α'=1, ξ'=4. Also, the number of discharge ports N
=α′η=13.

In this example, first, No. 10 outlet is the first
Scan so as to pass through the upper end of pixel U00. Then s=
(13/4) The paper is fed in the sub-scanning direction by p and the next scan is performed. By continuing the recording operation in this manner, a maximum of four dots can be formed within one pixel, and five-value gradation recording can be performed.

[0136] In Embodiment 3 and its variations described above, only one dot is formed from the same ejection port within the same pixel, but it goes without saying that multiple dots are formed from the same ejection port. can also be formed.

For example, in Modification 3, if up to two ink droplets can be ejected from the same ejection port to the same pixel, then
As shown in FIG. 22, nine gradations of 0 dot/1 pixel to 8 dots/1 pixel can be recorded. Of course, in this case, the maximum driving frequency of the recording head must be twice that of the third modification.

[0138] In Examples 1 to 3 and their modifications, one pixel is composed of a plurality of dots formed by ink droplets from different ejection ports in a plurality of scans, and these dots are It has been explained that they are formed at mutually shifted positions within the pixel.

Further, another aspect or another form of the above invention will be explained below as Examples 4 and 5.

(Example 4) In this example, an inkjet recording apparatus similar to that shown in FIGS. 1 and 2 is used. However, the number of ejection ports is 513.

[0141] A case will be described in which five gradation levels are recorded on A4 recording paper using the above apparatus. That is, recording is performed by changing the number of ink droplets per pixel in a range of 0 to 4.

FIG. 23 is a conceptual diagram for explaining the recording method of this embodiment. In addition, the pixel formation according to this example is shown in FIG.
Shown below.

The recording head 1 is provided with 513 ejection ports. When recording on recording paper, first scan N
o. Printing is performed while moving the carriage using only the ejection ports 385 to 513. As a result, dots are recorded with 0 or 1 ink droplets in the 1st to 129th pixels on the recording paper.

Next, the recording paper is sent upward by (128+1/4) ejection port pitch (=pixel pitch) (in the figure, for convenience, the recording head is moved downward), and the second
No. in scan. Printing is performed using ejection ports 257 to 513. As a result, No. The dots formed by the ejection ports 257 to 374 are No. 2 in the previous scan. 385～
The dots of the 1st to 128th pixels recorded with 513 ejection ports are shifted by 1/4 ejection port pitch (hereinafter referred to as
(Only 1/4 is recorded) is recorded at the bottom, and No. 385-51
The dots generated by the ejection port No. 3 are newly created at the 13th pixel from a position 1/4 below the dot of the 129th pixel.
Dots of the 0th to 257th pixels will be recorded. Therefore, each of the 1st to 129th pixels will be recorded with 0 to 2 ink droplets, and each of the 130th to 257th pixels will be recorded with 0 to 1 ink droplet. Next, the recording paper is again sent upward by (128+1/4) ejection port pitch, a third scan is performed, and No. Recording is performed using ejection ports 129 to 513. When such recording is repeated in sequence, by the time the recording of the 4th scan has finished, 0 to 4 pixels have been recorded for the 1st to 129th pixels, with the dots shifted downward by 1/4 pixel for each scan. As a result, an image with 5 gradations is obtained. If the recording is repeated in the same manner for the fifth and subsequent scans, a five-tone image will be formed over the entire surface of the A4 recording paper at the end of the 30th recording.

[0145] At the bottom edge of the image, the image edge is formed by sequentially stopping printing of 128 ejection ports used for each scan of the print head from the bottom.

Looking at each pixel in the sub-scanning direction of the image thus obtained, as shown in FIG.
One pixel is formed by a maximum of four ink droplets that are shifted downward by the amount of shift in the sub-scanning direction, that is, 1/4 pixel pitch, so ink can be made to land even in areas where ink does not land between adjacent pixels. is possible. This makes it possible to obtain sufficient density, especially in high-density areas of the image. Moreover, as described above, the dots of each pixel are formed by ink droplets that have landed at positions shifted downward by the amount of shift, so they are made up of ink droplets that are continuous in the sub-scanning direction.

Furthermore, since the shift amount of 1/4 ejection port pitch is for one scan, the ejection ports move downward by one ejection port pitch at the recording time of the fifth scan. In other words, one unused ejection port occurs every four scans. In this example, at the time of recording the 5th scan, No. 513
No. 2 ejection port is no longer required, and from then on every 4 scans
．． The seven outlets up to number 507 will be left as unused outlets. Therefore, for example, No. Since the ejection port No. 513 is used only for the first to fourth scans, no. If the drive data corresponding to 513 is "0", No. Even if the ejection port 513 has an ejection failure such as non-ejection, there is no problem with subsequent recording.

[0148] By performing such a recording method,
There may be unused ejection ports, and for example, it is possible to use a recording head that has ejection ports that have ejection defects such as non-ejection during manufacturing.

[0149] Even if there is an ejection failure in the ejection port that will not be used, the effect of the ejection failure on the density will be canceled out by the dots formed by other ejection ports during the first few scans using this ejection port. can be reduced.

(Modification 1 of Example 4) In this example, the inkjet recording apparatus shown in FIG. 5 is used. The recording head 1 of this example has 512 ejection ports arranged at a density of 16 ejection ports/mm. An example in which four-gradation recording is performed using this apparatus will be explained. In other words, the number of ink droplets per pixel is 0.
Recording is performed with changes in the range of ~3.

FIG. 25 is a conceptual diagram for explaining the recording method of this embodiment, and FIG. 26 shows pixel formation. First, the recording head 1 is positioned at the leftmost end in FIG. Recording is performed by rotating the drum once using only 170 ejection ports numbered 341 to 510. As a result, drive data “
Dots are formed according to “0” or “1”. Next,
In FIG. 5, the print head 1 is moved to the right, and the feed amount S of the print head is 512, the total number of ejection ports used,
When the maximum number of ink droplets (m = 3) and the shift amount are 1/3 ejection port pitch (1/3 pixel pitch), S = (170±
1/3) discharge port pitch. In this example, recording was performed when the shift amount was negative, that is, when the feed amount was set to (170-1/3) ejection port pitch. Here, the total number of scans is the ejection port array length of 32 m.
m (512 ejection ports), the maximum number of ink droplets (m=3), and the feed amount, the number is 22 times.

[0152] After moving the recording head to the right by the above-mentioned feed amount S, No. The drum is rotated once again using the ejection ports 171 to 510 to perform the next recording. As a result, No. Dots from 170 to 340 ejection ports are
Last time No. 1st to 1st recorded with ejection ports 341 to 510
It is formed at a position to the left of the 70th pixel by a shift amount of 1/3 pixel, and No. The discharge ports 341 to 510 are the 17th
0 to 1 dots are newly formed at the 171st to 340th pixels, 2/3 pixels to the right of the 0th pixel. Therefore, each pixel from 1st to 170th is 0 to 2
dots are formed. Then turn the recording head on again (17
0-1/3) After moving to the right by the discharge port pitch,
No. in scan. Recording is performed by rotating the drum once using ejection ports 1 to 510.

[0153] When such recording is repeated sequentially, at the end of the third scan, the 1st to 170th pixels are as follows:
The dots formed in each scan are shifted to the left by 1/3 pixel, and 0 to 3 dots are formed, resulting in a four-tone image. At the time of the fourth scan, each time the recording head moves, it moves to the left by (170-1/3) ejection port pitches, so the ejection ports are shifted leftward by one ejection port pitch, causing No. The outlet No. 1 becomes an unused outlet, and the outlet No. 1 becomes an unused outlet in its place. 511
The discharge port will be used. Similarly, at the time of the seventh scan, the ejection ports are shifted to the left by one ejection port pitch, so that No. The outlet No. 2 becomes an unused outlet, and the outlet No. 2 becomes an unused outlet. 512 outlets will be used. Furthermore, at the time of the 10th scan, No. Nozzle No. 3 is an unused discharge port, and the number of used discharge ports is No. 4-512 5
There will be 09 pieces. When this is repeated in sequence, the 22nd recording is completed, and a four-tone image is formed over the entire surface of the A4 recording paper. The discharge port that is not in use at this point is No.
There are 1 to 7 discharge ports, and 7 discharge ports are not used. Among these, No. Since the first ejection port has not been used since the first scan, there is no problem even if this ejection port has an ejection failure.

[0154] From the 20th time onward when recording the rightmost end of an image, the rightmost end of the ejection ports used is used. Every time the head moves, ejection is stopped from 512 nozzles, then 166 nozzles, then 170 nozzles, and then the remaining 170 nozzles to form an image edge.

[0155] Looking at each pixel in the recording head movement direction of the image obtained in this way, one pixel is formed by a maximum of three dots shifted by a displacement amount of 1/3 pixel pitch in the head movement direction. Therefore, it is possible to create unused ejection ports, and it becomes possible to use a recording head having a defective ejection port, which was conventionally considered to be defective, by replacing the ejection port.

(Modification 2 of Embodiment 4) Another modification using the same device as in Modification 1 above will be described. That is, a case will be described in which five gradations are recorded using this apparatus.

FIG. 27 is a conceptual diagram for explaining the recording method of this example, and FIG. 28 shows dot formation.

First, after positioning the recording head at the leftmost position in FIG. 5, a first scan is performed, and No. Recording is performed by rotating the drum once using only 128 ejection ports numbering 385 to 512. As a result, dots are formed in the 1st to 128th pixels from the left end of the recording paper in accordance with the drive data of "0" or "1". Next, {128-(2+1/4)}
After moving the recording head to the right by the feed amount equal to the ejection port pitch, No. The drum is rotated once again using the ejection ports 259 to 512 to perform recording. As a result, the shift amount is -(2+1/4) discharge pitch to the left, so No. Previous N at discharge ports 259 to 387
o. The 1st to 128th discharge ports formed by the 385th to 512th discharge ports
A dot is formed at a position 1/4 pixel to the left of the shift amount of 2+1/4 with respect to the No. th pixel. 387-5
For the 12 ejection ports, 0 to 1 dots are newly formed at the 129th to 254th pixels from a position 3/4 pixels to the right of the 128th pixel. Therefore, the first
For each 128th pixel, 0 to 2 dots are formed. Next, the recording head is moved to the right again by {128-(2+1/4)} ejection port pitch, and a third scan is performed. Recording is performed by rotating the drum once using the ejection ports 133 to 512. If such recording is repeated sequentially, at the end of the fourth scan, the dots ejected in each scan will be shifted to the left by 1/4 pixel at the 1st to 128th pixels on the image. 0 to 4 dots are formed and an image with 5 gradations is obtained. Again, the amount of shift from the 1st scan to the 4th scan is 6.
It is shifted to the left by +3/4 pixels. Then, at the recording time of the fifth scan, the shift with respect to each dot of the first scan is shifted to the left by 9 pixels, and there appears to be no shift amount on the image. Also, at this point there are some discharge ports that are not used, and no
．． This corresponds to the discharge ports numbered 1 to 9. If you continue recording further after this, at each scan of the 9th, 13th, etc., the state will be similar to that of the 5th scan described above,
In the 9th time, No. 10 to 18 discharge ports, No. 13 in the 13th time. The number of unused ejection ports, such as ejection ports 19 to 27, increases by 9 ejection ports every four scans. If this is repeated one after another, an image of five gradations will be formed over the entire surface of the A4 recording paper at the end of the 44th recording. The discharge port that is no longer in use at this point is No. The number of discharge ports is 1 to 96, and 96 are not used. Note that from the 41st time onward when recording the rightmost end of the image, the rightmost end of the ejection ports used is used. From 512 ejection ports, 38, then 128,
Recording is stopped at 128 points and 128 points at a time to form an image edge.

[0159] In this recording method, by forming unused ejection ports, for example, no. Even if printing is performed using a print head in which ejection ports 1 to 6 are defective ejection ports, no. 1
The ejection ports .about.6 can be replaced with other ejection ports depending on the amount of shift, and a recording head that was conventionally considered to be defective can be used as a good product.

(Embodiment 5) FIGS. 29, 30 and 31 are diagrams for explaining Embodiment 5 of the present invention. In this example, to simplify the explanation, the density of one pixel is expressed by a dot formed by ink droplets ejected from four different ejection ports. That is, five-value image formation will be explained. Further, the apparatus used in this example is the same as the apparatus shown in FIGS. 1 and 2.

FIG. 29 shows a recording head 1 having 128 ejection ports, and the 128 ejection ports are divided into blocks 11, 12, 13 and 14 of 32 ejection ports each. FIG. 30 is a timing chart showing the timing of drive pulses for each block shown in FIG. 29. Also, Figure 31
1 is a diagram illustrating at what positions ink droplets from each ejection port land within a pixel on a recording medium to form dots in this example.

FIG. 30a shows the drive waveform of the discharge port block 14, and at the same time, b represents the drive waveform of the discharge port block 13, c
d represents the drive waveform of the ejection port block 12, and d represents the drive waveform of the ejection port block 11, respectively. One drive pulse in FIG. 30 corresponds to each pixel, and its width is t. Further, the time difference between drive pulses between each block is set to t/4. Further, in the figure, the recording head is driven by the positive portion of the pulse, and the pulse width is set differently depending on the recording head used.

In FIG. 31, 301 represents the landing position on the recording medium of the ink droplet from the ejection port in the block 14, and 302 represents the landing position on the recording medium of the ink droplet from the ejection port in the block 13.
303 represents the landing position of the ink droplet from the ejection port in the block 12 and 304 from the ejection port in the block 11 on the recording medium. Further, 305 represents one pixel, and 306 represents a set of dots formed when all ink droplets land.

In the case where the recording head 1 in the above configuration performs main scanning, the paper is fed by a predetermined amount for each scan, and each pixel is formed by dots from a plurality of different ejection ports, for example, No. A case where a dot is formed at a predetermined pixel 305 by ejection ports 100, 68, 36, and 4 will be described.

First, by the first scan, No. Dots from 100 ejection ports form part of a pixel. No
．． The ejection port 100 belongs to the block 14, and ejects in accordance with the drive pulse of the drive waveform a. In this case, the ink droplet lands at the landing position 301 within the pixel 305 . Similarly, No. Since the ejection port 68 belongs to the block 13, ejection is performed using the drive waveform b. In this case, since the drive pulse b is shifted by t/4 from the drive pulse a, the ink droplet lands at a landing position 302 shifted from the position 301 in the pixel 305. No. Since the ejection port 36 belongs to the block 12, ejection is performed by the drive pulse c. In this case as well, since the driving pulse c is shifted by t/4 from the driving pulse b, the ink droplet lands at the landing position 303 within the pixel 305. And finally No. The ejection port 4 belongs to the block 11 and ejects in response to the drive pulse d. In this case, since the drive pulse d is shifted by t/4 from the drive pulse c, the ink droplet lands at the landing position 304 within the pixel 305. As described above, all the ink droplets constituting one pixel sequentially land each scan to form a set of dots 306. This set of dots 306 covers almost the entire area within the pixel 305.

In this embodiment, the drive pulses are set as shown in FIG. 30, but it goes without saying that the drive pulses for each block may be set at different positions within one pixel. Further, in this embodiment, the block is divided into four for convenience, but it is sufficient that the drive of each ejection port constituting one pixel is shifted by t/4, and the division need not be four. good. In addition, driving the head separately as described above also has the advantage of reducing the load on the head drive power source.

(Modification 1 of Example 5) FIGS. 32 and 33
32 is a diagram according to a modification of the present embodiment, and FIG. 32 is a diagram showing scanning (main scanning) by the recording head and feeding of a recording medium such as recording paper for each scan. FIG. 33 shows the landing positions of ink droplets from each ejection port on the recording medium. It is assumed that this example also uses the same image forming method as in Example 5 above.

[0168] In Fig. 32, 401 represents one time of paper feeding performed for each scan, and the feeding amount is A.
−3×α. 402 represents the next paper feed after paper feed 401, and the feed amount is A+α. 403 represents the next paper feed after paper feed 402, and the feed amount is A+α. 404 represents the next paper feed after paper feed 403, and the feed amount is A+α. Also, 405 represents the next paper feed, and the bookmark feed amount is A.
−3×α. Thereafter, the paper is fed in the same manner, and the amount of paper feeding is A+α three out of four times as shown in FIG. 32, and A-3×α the remaining one time. Note that the value of α is determined so that 3×α is smaller than the pixel width.

In FIG. 33, 501 is the No. 5 in the scanning performed between paper feed 401 and paper feed 402. It represents the landing position of ink droplets due to 100 ejection ports,
Similarly, 502 is N between paper feed 402 and paper feed 403.
o. 68 represents the landing position of the ink droplet by the ejection port 68, and 503 is No. 503 in the scanning performed between paper feed 403 and paper feed 404. 36 represents the landing position of the ink droplets by the ejection ports, and 504 indicates the paper feed 404.
and the paper feed 405. 4 shows the landing positions of ink droplets from ejection ports No. 4. Further, 505 represents one pixel, and 506 represents a collection of ink droplets formed when all the ink droplets land.

In the above configuration, image formation according to this example will be explained by focusing on one pixel as in the above embodiment.

In FIG. 32, after paper feed 401, scanning is performed, and in this scanning, No. The ejection port 100 ejects the ink droplet to the pixel 505, and the ink droplet lands at the landing position 50.
It lands on 1. Then, after scanning is completed, paper feed 40
2 will be implemented. Next, a scan is performed and No. 6
The ejection port 8 ejects ink onto the pixel 505, and the ink droplet lands at the landing position 502. This is No. 1 because the amount of paper feed 402 is A+α. The landing position is shifted by α from the landing position 501 of the ink droplet by the ejection port 100. Then, after the next paper feed 403, No. 1 is scanned. 3
The ink droplets from the nozzle 6 land at a landing position 503 that is α apart from the landing position 502 . Similarly, next paper feed 40
Scan No. 4. The ink droplet from the no. 4 ejection port lands at a landing position 504 that is α apart from the landing position 503.

An example of the image formed as described above is schematically shown in FIG. The example shown in the figure is an example in which the paper feed amount A=16/4=4 ejection port pitches using the ejection port 16.

[0173] By the way, the original paper feed amount at one time is A, and normally paper is fed 4 x A to form one pixel, but if the paper is fed as described above to form a misalignment. In this case, the total paper feed amount increases. As a result,
The formed image may have streaks. Therefore, here, the paper feed amount is set to A-3× once every four times.
After forming one pixel, α is set so that the normal feed amount becomes 4×A. That is, the ink droplets from each ejection port land at the same position in a pixel once every four times.

[0174] As described above, all the ink droplets constituting one pixel sequentially land to form a set of dots 506. This collection of ink droplets 506 covers almost the entire area within the pixel 505. As explained above, when all four ejection ports forming one pixel eject and obtain the highest density with four ink droplets, pixel 5 as shown in FIG.
The collection 506 of ink droplets that landed on the pixel 505 completely covers the entire pixel 505, and the ground on the recording material is no longer exposed. That is, as in this embodiment, the paper feed amount is set to be α larger than the normal paper feed amount A for three of the four paper feeds,
By setting the remaining one time to be reduced by 3 × α, each ink droplet will land at a different position within the pixel, so that the ejection volume that should achieve the desired maximum density and the required number of gradations will be determined. It is possible to obtain it.

[0175] In this example, the paper is set to be increased by α for 3 out of 4 times, and the remaining one is set to be decreased by 3×α. Needless to say, the effect is exactly the same even if the number of paper feeds is set to be decreased by α and the remaining number of times is set to be increased by 3×α. In addition, all four paper feeds, that is, all paper feeds that form an image, are set as A-4×n×α-α (n is zero or a positive integer), and one or The same effect can be obtained by disabling a plurality of ejection ports so that the ejection ports constituting each pixel are sequentially changed.

(Modification 2 of Embodiment 5) FIG. 35 is a diagram showing a modification of Embodiment 5 of the present invention.

In this example, the landing position of the ink droplet according to Example 5 is shifted within one pixel in the main scanning direction, and the landing position of the ink droplet according to Modification 1 of Example 5 is shifted within one pixel in the paper feeding direction. It is a combination of things that shift. The ink droplet landing position control is a combination of both the fifth embodiment and the first modification thereof.

[0178] In these figures, the same numbers represent the landing positions of ink droplets ejected from the same ejection ports, and 601 is No. 601. No. 100 represents the landing position of the ink droplet ejected from the ejection port, and No. 68
Depending on the discharge port, 603 is No. With 36 discharge ports,
604 is No. This point represents the landing position of each ink droplet ejected by the four ejection ports. Also, the same figure (a)
, (b), (c), and (d) are representative representations of landing positions for every 32 pixels in the paper feeding direction, and 605 represents one pixel of each.

[0179] The reason why the landing position is as shown in the figure (a) can be easily explained from the fifth embodiment and the first modification thereof. That is, by dividing the recording head into blocks and driving them separately in the direction of the ejection port arrangement, the landing position of the ink droplets is shifted within the pixel in the horizontal direction of the pixel in the figure, and the paper is fed three times out of four times by A+α. A- for the remaining one time
By feeding at 3α, the landing position of the ink droplet is shifted within the pixel in the vertical direction of the pixel in the figure. In addition, in the same figure, the reason why the landing positions are arranged irregularly other than in (a) is that the order of the position where dots are formed and the paper feed is different for each pixel shown in (a) to (d). In (b), the paper feed before the dot is formed by the last ink drop is A-
In (c), the paper feed after the dot was formed by the second ink droplet and before the dot was formed by the third ink droplet was A-3×α. ,
In (d), first after dot formation by ink droplets and second.
Paper feeding before dot formation by the second ink droplet is A-3
This is because ×α.

By the way, in (b), (c), and (d) of the same figure, it appears that not all parts of the pixels are covered, but the image is expressed by a collection of pixels, and the figure In each of (b), (c), and (d), when considering the surrounding area of the pixel, the arrangement of dots is the same as in (a) in the same figure, and it can be seen that all pixels are covered. Recognize.

[0181] As explained above, in this example, when the recording medium has a very low bleeding rate or the number of pixels in the recording head scanning direction is very large, the fixation of the droplet that landed one scan ago will not progress very much. This is especially effective when

[0182] In the fifth embodiment and its modifications, a so-called quinary image in which one pixel is formed by four dots has been described above, but it goes without saying that the number of dots has no relation to the number of dots. When the number of dots increases, it is not necessary to configure all the dots to land at different positions. For example, three of the four dots may be configured to land at different positions, and the remaining one may be configured to land at the same position as the other three;
Two of them may be placed at the same landing position, and the other two may be placed at positions different from the two landing positions. In this case, it goes without saying that the desired maximum density must be obtained using the above pixel forming method. In the fifth embodiment and its modified examples, the case where the pixel size (pitch) and the ejection port pitch are equal in all cases has been described, but this example is not limited to pixel size=nozzle pitch.

[0183] In Examples 1 to 5 and their modifications, an inkjet type recording device and ejection ports etc. were described as recording elements used therein, but other types of recording such as a thermal transfer type etc. Of course, the present invention can be applied to the apparatus and its recording element.

(Others) The present invention particularly relates to means for generating thermal energy as energy used for ejecting ink in an inkjet recording system.
For example, the present invention provides an excellent effect in a recording head or recording apparatus that is equipped with an electrothermal converter (for example, an electrothermal converter, a laser beam, etc.) and uses the thermal energy to cause a change in the state of the ink. This is because such a system can achieve higher recording density and higher definition.

[0185] For its typical configuration and principle, see, for example, US Pat. No. 4,723,129 and US Pat.
Preferably, it is carried out using the basic principles disclosed in the '796 specification. This method is the so-called on-demand type.
It can be applied to any continuous type, but in particular, in the case of an on-demand type, it is applicable to the electrothermal converter placed corresponding to the sheet holding the liquid (ink) or the liquid path. , by applying at least one drive signal that corresponds to recorded information and provides a rapid temperature rise exceeding nucleate boiling, the electrothermal transducer generates thermal energy to produce film boiling on the thermally active surface of the recording head. As a result, liquid (ink) is generated in one-to-one correspondence with this drive signal.
This is effective because air bubbles can be formed inside. Due to the process of growth and contraction of the bubbles, liquid (ink) is ejected through the ejection opening (ejection port) to form at least one droplet. It is more preferable to use this drive signal in a pulse form, since the growth and contraction of bubbles can be carried out immediately and appropriately, making it possible to eject liquid (ink) with particularly excellent responsiveness. As this pulse-shaped drive signal, US Pat. No. 4,463,359
Suitable materials are those described in No. 4,345,262. Furthermore, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

[0186] In addition to the configuration of the recording head, which is a combination of ejection ports, liquid paths, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44 disclose a configuration in which a heat acting part is arranged in a bending region.
A configuration using the specification of No. 59600 is also included in the present invention. In addition, JP-A-59-123670 discloses a configuration in which a plurality of electrothermal transducers have a discharge section having a common slit as a discharge opening, and a hole absorbing pressure wave of thermal energy is disclosed. The effects of the present invention are also effective even with a configuration based on Japanese Patent Application Laid-Open No. 138461/1983, which discloses a configuration in which a discharge portion is provided corresponding to a discharge portion. That is, regardless of the form of the recording head, according to the present invention, recording can be performed reliably and efficiently.

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

Further, it is preferable to add ejection recovery means for the recording head, preliminary auxiliary means, etc. to the configuration of the recording apparatus of the present invention, since this further stabilizes the effects of the present invention. Specifically, these include capping means, cleaning means, pressure or suction means for the recording head, electrothermal transducers that generate thermal energy to eject ink droplets necessary for recording, and Preheating means that performs preheating using a different heating element or a combination thereof, and preliminary ejection means that performs ejection other than recording.

[0189] Regarding the type and number of recording heads to be mounted, for example, in addition to a single head installed for single-color ink, there are also configurations for multiple inks with different recording colors and densities. A plurality of them may be provided. That is, for example, the recording mode of the recording apparatus is not limited to a recording mode for only a mainstream color such as black, but may also be a recording mode in which the recording head is configured integrally or in a combination of multiple colors, Alternatively, the present invention is extremely effective for an apparatus equipped with at least one of the full-color recording modes using color mixing.

[0190] Furthermore, the ejection port array is not limited to one row, but can also be configured to have a plurality of rows (for example, one row has 20 ejection ports, and these are arranged in four rows).

In addition, in the embodiments of the present invention described above, the ink is described as a liquid, but even if the ink solidifies at room temperature or lower, it can be used as long as it softens or liquefies at room temperature. , can be liquefied and used during recording, so it can be used in the present invention. Alternatively, in the inkjet method, in some cases, the temperature is adjusted so that the ink itself is kept within a range of 30° C. to 70° C., and the temperature is controlled so that the viscosity of the ink is within a stable ejection range. In this case 30℃
An ink that becomes liquid at temperatures above 70° C. or below can be used. In addition, in order to actively prevent the temperature of the ink itself from rising due to thermal energy by using the energy to change the state of the ink from a solid state to a liquid state, or to prevent the ink from evaporating, it is first liquefied by heating. You may also use ink. In any case, by applying thermal energy in accordance with the recording signal, the ink is liquefied and the liquid ink is ejected, or the ink has already begun to solidify by the time it reaches the recording medium. The present invention is also applicable when using ink that is liquefied for the first time. The ink in this case is
JP-A-54-56847 or JP-A-60-7
The material may be used for recording while being held as a liquid or solid material in the recesses or through holes of a porous sheet, as described in Japanese Patent No. 1260. In the present invention, the most effective method for each of the above-mentioned inks is to perform the above-mentioned method of causing film boiling.

In addition, the inkjet recording device according to the present invention can be used as an image output terminal for information processing equipment such as a computer, a copying device combined with a reader, etc., and a facsimile machine having a sending/receiving function. It may also take the form of a device.

[0193]

Effects of the Invention As is clear from the above description, the plurality of dots constituting each pixel are formed by different recording elements through a plurality of first relative movements, and are formed at different positions in the pixel. is formed.

As a result, variations in recording characteristics among multiple recording elements are averaged out in the dot formation of each pixel, and sufficient density can be obtained, thereby reducing the effects of unevenness, streaks, etc. This makes it possible to record images with high quality.

[Brief explanation of drawings]

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

FIG. 2 is a block diagram showing a control configuration of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 3 is a conceptual diagram for explaining a recording operation according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram showing dot formation according to the above embodiment.

FIG. 5 is a schematic perspective view showing main parts of an inkjet recording apparatus according to another embodiment of the present invention.

FIG. 6 is a schematic diagram showing dot formation according to a modification of Example 1.

FIG. 7 is a schematic diagram showing dot formation according to another modification of the first embodiment.

FIG. 8 is a conceptual diagram for explaining a recording operation according to another modification of the above embodiment.

FIG. 9 is a conceptual diagram for explaining a recording operation according to a second embodiment of the present invention.

FIG. 10 is a schematic diagram showing dot formation according to the second embodiment.

FIG. 11 is a schematic diagram showing dot formation according to a modification of the second embodiment.

FIG. 12 is a conceptual diagram for explaining a recording operation according to another modification of the second embodiment.

FIGS. 13A and 13B are conceptual diagrams showing dot formation according to Example 3 of the present invention.

FIG. 14 is a diagram showing the relationship between pixels, the number of scans, and the ejection port number according to the third embodiment.

FIG. 15 is a conceptual diagram showing the contents of the drive data RAM according to the third embodiment.

FIG. 16 is a schematic diagram for explaining dot formation according to a modification of the third embodiment.

FIG. 17 is a diagram showing the relationship between pixels, the number of scans, and the ejection port number according to the above modification.

FIG. 18 is a conceptual diagram for explaining a recording operation according to another modification of the third embodiment.

FIG. 19 is a schematic diagram showing dot formation according to the above modification.

FIG. 20 is a schematic diagram showing another example of dot formation according to the above modification.

FIG. 21 is a conceptual diagram for explaining a recording operation according to yet another modification of the third embodiment.

FIG. 22 is a schematic diagram showing dot formation according to still another modification of the third embodiment.

FIG. 23 is a conceptual diagram for explaining the recording operation according to the fourth embodiment of the present invention.

FIG. 24 is a schematic diagram showing dot formation according to the fourth embodiment.

FIG. 25 is a conceptual diagram for explaining a recording operation according to a modification of the fourth embodiment.

FIG. 26 is a schematic diagram showing dot formation according to the above modification.

FIG. 27 is a conceptual diagram for explaining a recording operation according to another modification of the fourth embodiment.

FIG. 28 is a schematic diagram showing dot formation according to the above modification.

FIG. 29 is a schematic diagram showing a recording head according to Example 5 of the present invention.

FIG. 30 is a timing chart of recording head drive pulses according to the fifth embodiment.

31 is a schematic diagram showing dot formation according to Example 5. FIG.

FIG. 32 is a conceptual diagram for explaining paper feeding according to a modification of the fifth embodiment.

FIG. 33 is a schematic diagram showing dot formation according to the above modification.

FIG. 34 is a schematic diagram showing dot formation according to the above modification in relation to paper feeding.

FIG. 35: Each of (a) to (d) is the same as in Example 5 above.
FIG. 12 is a schematic diagram showing dot formation according to still another modification of FIG.

[Explanation of symbols]

1 Recording head 2 Recording paper 3 Platen roller 4 Carriage 5A, 5B Guide shaft 6 Ink supply tube 7 Flexible cable 100 Main controller 100M frame memory 102 Paper feed motor 102D Motor driver 104 Carriage motor 104D Motor driver 110 Driver controller 110D head driver 110M Drive data RAM

Claims (21)

[Claims] 1. A first relative movement between the recording medium and the recording head for forming dots on the recording medium by the plurality of recording elements using a recording head equipped with a plurality of recording elements; , a second relative movement between the recording medium and the recording head, and recording is performed using a set of pixels constituted by the dots, the recording method comprising the step of performing the first relative movement a plurality of times. A recording method characterized in that the pixel is formed by a plurality of dots each formed by a different recording element, and the plurality of dots are formed at different positions in the pixel. 2. The recording method according to claim 1, wherein the plurality of dots are formed at different positions in the direction of the first relative movement. 3. The recording method according to claim 1, wherein the plurality of dots are formed at different positions in the direction of the second relative movement. 4. The recording method according to claim 1, wherein the plurality of dots are formed at different positions in the first and second relative movement directions. 5. The width of the pixel in the second relative movement direction is p, the movement amount of the second relative movement is s, and the pitch of the plurality of recording elements in the second relative movement direction is q, the number of the plurality of recording elements is N, the maximum number of dots that each of the plurality of recording elements can form on the pixel is K, and the maximum number of dots to be formed on the pixel is m. , s=ap, q=bp, {(N-1
)b+1}/a≧2, NK/a≧m, and a/b, b/a are both non-integers. Method. 6. The width of the pixel in the second relative movement direction is p, the movement amount of the second relative movement is s, and the pitch of the plurality of recording elements in the second relative movement direction is p. q, the number of the plurality of recording elements is N, the maximum number of dots that each of the plurality of recording elements can form on the pixel is K, and the maximum number of dots to be formed on the pixel is m. , s=ap, q=bp, {(N-1
)b+1}/a≧2, NK/a=m, a/b, b/a are both non-integers, and Nb/a is a non-integer. 4. The recording method according to any one of 4. 7. The width of the pixel in the second relative movement direction is p, the movement amount of the second relative movement is s, and the pitch of the plurality of recording elements in the second relative movement direction is q, the number of the plurality of recording elements is N, and s=a
When expressed as p, q=bp, a, b are expressed as a=η/ξ, b=β/α by mutually prime sets of natural numbers α and β, η and ξ, respectively, and α and ξ
When g is the greatest common divisor of
Claims 1 and 3 characterized in that the conditions ξ′>1 and βξ′>1 hold true.
, 4. The recording method described in any one of 4. 8. Forming a recording element that does not participate in the formation of the dot by shifting a corresponding pixel of each of the plurality of recording elements with respect to the formation of the dot by performing the second relative movement a plurality of times. The recording method according to claim 3 or 4, characterized in that: 9. The recording method according to claim 1, wherein the amount of movement of the second relative movement is variable. 10. The recording head includes, as the recording element, an ink ejection port and a thermal energy generating means for generating thermal energy for ejecting ink from the ink ejection port, and generates bubbles using the thermal energy. 10. The recording method according to claim 1, wherein ink is ejected from the ink ejection port as the bubbles are generated, and the dots are formed by the ejected ink. 11. A first relative movement between the recording medium and the recording head in order to form dots on the recording medium by the plurality of recording elements using a recording head equipped with a plurality of recording elements; , a second relative movement between the recording medium and the recording head, and in a recording apparatus for performing recording by a set of pixels constituted by the dots, the first relative movement is performed a plurality of times. The first pixel is formed by a plurality of dots formed by different recording elements, and the plurality of dots are formed at different positions in the pixel.
and a control means for controlling the second relative movement. 12. The width of the pixel in the direction of the second relative movement is p, the amount of movement of the second relative movement is s,
The pitch of the plurality of recording elements in the second relative movement direction is q, the number of the plurality of recording elements is N, and the maximum number of dots that each of the plurality of recording elements can form on the pixel is K. , the maximum number of dots to be formed in the pixel is m, and when expressed as s=ap, q=bp, {(N−
1) b+1}/a≧2, NK/a≧m, a/b,,b/
12. The recording apparatus according to claim 11, wherein each of the conditions that a is a non-integer is satisfied. 13. The width of the pixel in the direction of the second relative movement is p, the amount of movement of the second relative movement is s,
The pitch of the plurality of recording elements in the second relative movement direction is q, the number of the plurality of recording elements is N, and the maximum number of dots that each of the plurality of recording elements can form on the pixel is K. , the maximum number of dots to be formed in the pixel is m, and when expressed as s=ap, q=bp, {(N−
1) b+1}/a≧2, NK/a=m, a/b, b/a
12. The recording apparatus according to claim 11, wherein the following conditions hold true: both are non-integers, and Nb/a is a non-integer. 14. The width of the pixel in the direction of the second relative movement is p, the amount of movement of the second relative movement is s,
The pitch of the plurality of recording elements in the second relative movement direction is q, the number of the plurality of recording elements is N, and s=
When expressed as ap, q=bp, a, b are expressed as a=η/ξ, b=β/α by mutually prime natural number sets α and β, η and ξ, respectively, and α and ξ
When g is the greatest common divisor of
12. The recording apparatus according to claim 11, wherein the following conditions are satisfied: ξ'>1 and βξ'>1. 15. The recording head includes, as the recording element, an ink ejection port and a thermal energy generating means for generating thermal energy for ejecting ink from the ink ejection port, and generates bubbles using the thermal energy. 15. The recording apparatus according to claim 11, wherein ink is ejected from the ink ejection port as the bubbles are generated, and the dots are formed by the ejected ink. . 16. Using a recording head equipped with a plurality of recording elements, performing relative movement between the recording medium and the recording head in order to form dots on the recording medium by the plurality of recording elements, and A recording method that performs recording by a set of pixels constituted by dots, wherein the pixel is constituted by a plurality of dots formed by different recording elements by each of the plurality of relative movements, and the plurality of dots are are formed at different positions in the pixel. 17. A recording medium and the recording head for forming dots on the recording medium with ink ejected from the plurality of ink ejection openings, using a recording head equipped with a plurality of ink ejection openings. a first relative movement of;
a second relative movement between the recording medium and the recording head, and performs recording using a set of pixels constituted by the dots, the recording method comprising: performing a second relative movement between the recording medium and the recording head;
p is the width in the direction of the relative movement, s is the movement amount of the second relative movement, q is the pitch of the plurality of ink ejection ports in the direction of the second relative movement, and is the number of the plurality of ink ejection ports. is N, the maximum number of dots that each of the plurality of ink ejection ports can form on the pixel is K, the maximum number of dots that should be formed on the pixel is m, and s=ap, q=
When expressed as bp, {(N-1)b+1}/a≧2, NK/a≧m, a/b
, b/a are both non-integers. 18. A recording medium and the recording head for forming dots on the recording medium using ink ejected from the plurality of ink ejection openings, using a recording head equipped with a plurality of ink ejection openings. a first relative movement of;
a second relative movement between the recording medium and the recording head, and performs recording using a set of pixels constituted by the dots, the recording method comprising: performing a second relative movement between the recording medium and the recording head;
p is the width in the direction of the relative movement, s is the movement amount of the second relative movement, q is the pitch of the plurality of ink ejection ports in the direction of the second relative movement, and is the number of the plurality of ink ejection ports. is N, the maximum number of dots that each of the plurality of ink ejection ports can form on the pixel is K, the maximum number of dots that should be formed on the pixel is m, and s=ap, q=
When expressed as bp, {(N-1)b+1}/a≧2, NK/a=m, a/b
, b/a are both non-integers, and Nb/a is a non-integer. 19. A recording medium and the recording head for forming dots on the recording medium using ink ejected from the plurality of ink ejection openings, using a recording head equipped with a plurality of ink ejection openings. a first relative movement of;
a second relative movement between the recording medium and the recording head, and performs recording using a set of pixels constituted by the dots, the recording method comprising: performing a second relative movement between the recording medium and the recording head;
p is the width in the direction of the relative movement, s is the movement amount of the second relative movement, q is the pitch of the plurality of ink ejection ports in the direction of the second relative movement, and is the number of the plurality of ink ejection ports. When N is expressed as s=ap, q=bp,
a and b are expressed as a=η/ξ, b=β/α by mutually prime natural number sets α and β, η and ξ, respectively, and α and ξ
When g is the greatest common divisor of
An inkjet recording method characterized by satisfying the following conditions: ξ′>1, βξ′>1. 20. A recording medium and the recording head for forming dots on the recording medium with ink ejected from the plurality of ink ejection openings, using a recording head equipped with a plurality of ink ejection openings. a first relative movement of;
a second relative movement between the recording medium and the recording head, and performs recording by a set of pixels constituted by the dots, the method comprising: performing a second relative movement between the recording medium and the recording head; An inkjet recording method, characterized in that, regarding the formation of the dots, ink ejection ports that do not participate in the formation of the dots are formed by shifting pixels to which each of the plurality of ink ejection ports corresponds. 21. A recording medium and the recording head for forming dots on the recording medium with ink ejected from the plurality of ink ejection openings, using a recording head equipped with a plurality of ink ejection openings. a first relative movement of;
A recording method that performs a second relative movement between the recording medium and the recording head, and performs recording by a set of pixels constituted by the dots, the amount of movement of the second relative movement being: An inkjet recording method characterized by being variable.