JPH0858119A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE: To record a color image reduced in density irregularity and occurrence of no white stripe and carry out the accurate color lapping by arranging respective emitting part groups and respective emitting parts on the same straight line and setting a fundamental recording pitch, the pitch and number of respective emitting parts and the interval between the emitting parts provided at the same end of respective emitting part groups so as to satisfy a specific relational expression. CONSTITUTION: A plurality of color inks are emitted from a plurality of emitting part groups 12-15 consisting of a plurality of the emitting parts corresponding to the color inks and arranged on the same straight line to record the strips of the respective color inks on a recording medium and this operation is repeated to complete recording. When a fundamental recording pitch is set to P0 , the pitch and number of the respective emitting parts are set to P1 and n and the interval between the emitting parts provided to the same end of the respective emitting part groups is set to P2 , P1 >P0 and P2 =P0 ×(n+m) (m; integer) are formed. As a result, since the joints of respective colors are arranged at an equal interval, density irregularity becomes inconspicuous and the white stripe of the joint of monochromatic strips can be prevented. Since color lapping can be accurately performed, a high-grade color image can be obtained in the min. cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for ejecting color ink to perform color recording.

[0002]

2. Description of the Related Art Conventionally, as a color recording apparatus, recording methods such as thermal transfer, electrophotography and ink jet have been used. Among them, the inkjet recording method has been particularly attracting attention in recent years because it can provide high-definition images at low cost.

As a configuration of a color ink jet recording apparatus, as shown in FIG. 10, there is known a method of recording by arranging a plurality of heads for ejecting (discharging) inks of three primary colors and repeatedly scanning the recording paper. Has been. Also,
A method of ejecting ink of a plurality of colors from a single head is also known, as in Japanese Patent Publication No. 12675/1989.

[0004]

However, the above-mentioned conventional example has the following drawbacks. That is, when a plurality of ejecting portions, for example, ejecting portion nozzles are formed on a single head, a difference in the volume of the ejected droplets is likely to occur between the center and the end of the nozzle group. This is due to, for example, the difference in the aperture of the nozzle due to the difference in the flow of the etching liquid when the nozzle is formed by etching, the difference in the pressure propagation when ejecting the droplet, and the like. Such a difference in droplet volume causes unevenness in density on the recording paper, and deteriorates image quality.

In particular, in the above-mentioned conventional example, when recording is performed using, for example, three primary colors (yellow, magenta, and cyan), since the end portions of the respective colors coincide with each other, density unevenness is amplified and recognized as stripes. There was a problem.

Therefore, as in Japanese Patent Laid-Open No. 6-135007, the seams of the Y, M, and C color bands are arranged equidistantly from the seams of the other two color bands, which results in uneven density. Amplification could be improved.

However, since the paper feed mechanism of the main body of the recording apparatus has a tolerance, when the paper feed is large, the seams of the single color bands may be widened and white stripes may occur, resulting in remarkable image quality. May be damaged. In order to improve this, it is conceivable to shift in the direction of narrowing the joint of the monochromatic band, and in the case of an ordinary monochromatic head, the ejection port pitch is made larger than the recording pitch. However,
In the case of a configuration in which a plurality of ejection unit groups including a plurality of ejection units are arranged on the same straight line as disclosed in JP-A-6-135007, the ejection port pitch is larger than the recording pitch and the interval between the ejection port groups is set to the ejection port. When it is an integral multiple of 8 of the partial pitch, the positions of the dots of the respective colors are displaced, and the reproducibility of the color expressed by overlapping two or more colors is deteriorated.

Therefore, an object of the present invention is to provide an ink jet recording apparatus capable of recording a color image with little density unevenness and no white stripes and capable of accurately superposing colors.

[0009]

According to the present invention, a plurality of color inks are ejected from a plurality of ejection unit groups corresponding to the plurality of ejection units, and a band of each color is formed on a recording medium. In an inkjet recording apparatus that completes recording by recording and repeating this, each ejection unit group and each ejection unit are arranged on the same straight line, and the basic recording pitch P ₀ , each ejection unit pitch, and the number are P ₁ and n, where P ₂ is the interval between ejection parts located at the same end of each ejection part group (hereinafter, nozzle group interval or ejection part group interval), P ₁ > P ₀ P ₂ = P ₀ × (n + m) (m Is a whole number), it is possible to record a color image with less density unevenness and no white stripes, and to perform high-precision color superimposition to provide a high-quality color image. It was done.

[0010]

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

(First Embodiment) FIG. 1 shows a first embodiment of the present invention. Reference numeral 11 is a single recording head, 12 is a discharge port group that discharges yellow (Y) ink, 13 is a discharge port group that discharges magenta (M) ink, and 14 is a cyan (C) ink discharge A discharge port group 15 for discharging black (Bk) ink. Y, M,
The number of nozzles in each nozzle group C is 24, and the number of nozzles Bk is 64.

A method of setting each nozzle pitch P ₁ will be described with reference to FIG.

Taking the 360 dpi required for high precision color recording as an example, the basic recording pitch is P ₀ = 70.56 μm. The portions of interest are the dots on the recording paper formed by ejecting the 24th nozzle of the a scan and the dots on the recording paper formed by ejecting the first nozzle of the (a + 1) scan. Here, these dot diameters are D = 110μ
m, the total variation of paper feed variation / dot diameter variation / dot deviation is δ = 50 μm, the dot clearance y is y = D−P ₀ −δ = 110−70.56−50 = −10.56 (Here, the positive sign has dot overlap (no white blank) and the negative has white blank), resulting in a white blank of 10.56 μm.

Therefore, P ₁ may be set to P ₁ = P ₀ + y / (n-1) = 70.56 + 10.56 / (24-1) = 71.02 μm. Here, when the total variation δ is in the opposite direction, y = 89.44 μm, and there is considerable dot overlap, but since it spreads on the paper, the image quality is not as bad as that of white blank.

FIG. 3 shows the printing result with this configuration. In the figure, the sub-scanning amount (paper feed amount) is in units of 24 dots, and 24 of the 64 black nozzles are used. Further, FIG. 9A shows the printing process of the first line in FIG. As can be seen from FIG. 3, the seams of the bands of the respective colors are 24/3, and the density unevenness is evenly distributed on the recording paper, making it less noticeable. Further, the color superposition of each color can be accurately realized because the nozzle group interval is an integral multiple of the basic recording pitch P ₀ . Further, as disclosed in Japanese Patent Application Laid-Open No. 1-208143, by making the interval between the nozzle groups 1 dot or more, ink of different colors does not come into contact with paper in one carriage scan. It is possible to prevent the deterioration of the image quality due to the mixing of the unfixed inks.

Here, the Bk ink and the color ink are made to have different physical properties, and a better image quality can be obtained.
Since it is necessary that the color inks do not overflow on the recording paper even when two colors are superposed, and it is necessary to obtain the density even with a single color, it is preferable to use a large ink that spreads on the recording paper. In order to realize this, the surface tension of the color ink is set to about 35 dyne / cm ² and small dots are ejected (40 pl for 360 dpi).
Rank).

Further, since the character quality of Bk ink is required, it is preferable to use one having a small spread on the recording paper.
High density recording with less feathering is possible. To achieve this, the surface tension of Bk ink should be 45d.
It is set to about yne / cm ² and a large dot (80 pl in the case of 360 dpi) is ejected. In accordance with this, the above is possible by changing the nozzle parameters (ejection area, ejection energy element (heater in the case of BJ), nozzle resistance, etc.) with Bk and color.

Further, since it is composed of a single head, it can be constructed at low cost. In addition, 64 black nozzles are provided because high-speed printing is performed by using all the black nozzles when images of only black are continuous.

Further, an example of the circuit of this embodiment is shown in FIG. Normally, the image data sent from the host computer is raster data, but in order to print with the head as in this embodiment, it must be converted into data in the nozzle array direction. Therefore, when transferring from the reception buffer 21 to the drawing buffer 22, data for 8 nozzles
As a unit (1 byte), data for 8 nozzles in the raster direction are stored together in a buffer. Drawing buffer 22
Has a predetermined number of such buffers, and at the time of printing, 3 bytes are sequentially read from the 3 buffers of Y, and then read from the buffers of M, C, and Bk.

Here, it is characteristic that the nozzles of each color are
This means that the signals recorded at the same time are read out from different portions of the drawing data of each color because they are arranged so as to be offset from the recording paper. That is, the shaded data in FIG. 4 is recorded at the same time. In order to easily realize this, it is desirable that the difference between the read positions of the data of the respective colors be in units of 1 byte, that is, equivalent to 8 nozzles.

If this corresponds to, for example, 4 nozzles,
As a circuit configuration, it is necessary to use a 4-bit unit buffer or add a circuit for shifting data by 4 bits after reading. In the former case, the number of buffers increases, and in the latter case, the number of circuits increases, which is not preferable. Therefore, assuming that the nozzle group interval P _{2 in} the configuration of this embodiment is m = 8, P ₂ = P ₀ (24+
8) is the most suitable configuration. Of course, from the viewpoint of the circuit configuration, the effect is the same in the unit of "m bytes", in other words, the nozzle group interval may be a multiple of 8 nozzle pitches.

FIG. 5 is a perspective view of an ink jet printer equipped with an ink cartridge and a carriage to which the present invention is applicable.

The carriage 101 has a print head 102 and a cartridge guide 103 mounted thereon, and can scan on a guide shaft 104 and a guide shaft 105. The recording paper 106 is fed into the main body by a paper feed roller 107, a paper feed roller 108, a pinch roller (not shown), and the paper pressing plate 1.
It is pinched by 09 and is fed to the front surface of the paper feed roller 102 for printing. Two types of ink cartridges, a color ink cartridge 110 containing three colors of yellow, magenta, and cyan, and a black ink cartridge 111 are separately inserted into the cartridge 103 and communicate with the print head 102.

The print head 102 will be described in detail with reference to FIG. 6. Yellow, magenta, cyan, and black ejection port groups are arranged in a straight line on the front surface of the print head 102. Each group has 24 discharge ports for yellow, magenta, and cyan, and 64 discharge ports for black, and each nozzle group has a space of about 8 nozzles. In addition, these nozzles are 3 per inch
They are arranged at a density of 60 (360 dpi).

Each of these ejection ports is provided with an ink liquid passage communicating with the ejection port, and a common liquid for supplying ink to these liquid passages is provided behind the portion where the ink liquid passage is provided. A room is provided. The ink liquid path corresponding to each of the ejection ports is provided with an electrothermal converter that generates thermal energy used for ejecting ink droplets from these ejection ports and electrode wiring for supplying electric power to the electrothermal converter. ing. These electrothermal converters and electrode wirings are formed by a film forming technique on a 201 substrate made of silicon or the like. Further, the ejection port, the ink liquid passage, and the common liquid chamber are formed by stacking a partition wall made of a resin, a glass material, a top plate, etc. on the substrate. Further on the rear side, a drive circuit for driving the electrothermal converter based on a recording signal is provided in the form of a printed circuit board.

The silicon substrate and the printed circuit board 202 are parallel to the same aluminum plate 203, and the protruding pipe 2
Reference numerals 04 to 207 project from a plastic member 208 called a distributor which extends in a direction perpendicular to the silicon substrate, and further communicates with a flow passage inside thereof, and the flow passage communicates with a common liquid chamber.

There are four flow paths in the distributor, one for yellow, one for magenta, one for cyan, and one for black, and each common liquid chamber is connected to a pipe.

About 40 ng from the yellow, magenta, and cyan discharge ports provided on the print head 102.
Ink of about 80 ng is ejected from the ejection port for black at a frequency of 5.4 kHz.

The print head 102 has 24 discharge ports for yellow, magenta, and cyan, respectively, while it has 64 discharge ports for black. This is because when black-only images are continuous, high-speed printing is performed by using all black nozzles, and in the case of an image in which color images are mixed, the same as the color ejection port 24 Printing is performed using individual nozzles.

Further, when printing only black, as shown in FIG.
As shown in FIG. 8, the black-only monochrome head 200 can be replaced so that the speed can be increased. Here, it is desirable that the nozzle row of the monochrome head 200 and the nozzle row of the color head 102 have the following relationship.

The endmost nozzle 202 of the monochrome head and the endmost nozzle 302 of the Bk portion of the color head are located at the same distance z from the reference plane for mounting the carriage. This makes it possible to easily make the printing areas on the recording paper the same. Further, the number of nozzles P of the monochrome head is
By the signal processing of the image data described above, it can be understood that it is preferable to set P = Q + 8 × l (1 is an integer), where Q is the number of Bk nozzles of the color head.

In the case of FIG. 8, when the number of nozzles for the color head is 24 nozzles for each of Y, M, and C and the number of nozzles for Bk64 is 128, the number of nozzles for the monochrome head is most effective. And the printing speed is doubled.

The present invention brings excellent effects particularly in a recording head and a recording apparatus of a system utilizing thermal energy among the ink jet recording systems.

Regarding the typical structure and principle thereof, see, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
It can be applied to any of the continuous type, but especially in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal that gives a rapid temperature rise over the nucleate boiling corresponding to the recorded information, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. As a result, bubbles can be formed in the liquid (ink) in a one-to-one correspondence with this drive signal, which is effective. By the growth and contraction of the bubbles, liquid (ink) is ejected through the ejection opening,
Form at least one drop. It is more preferable to make this drive signal into a pulse shape because bubbles can be immediately and appropriately grown and contracted, so that liquid (ink) ejection with excellent responsiveness can be achieved. The pulse-shaped drive signal is described in U.S. Pat. No. 4,463,359 and No. 4345.
Those as described in the '262 patent are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise of the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the ejection port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angle liquid passage) as disclosed in the above-mentioned specifications, U.S. Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of No. 459600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the structure corresponding to the discharging portion is disclosed in Japanese Patent Laid-Open No. 59-138461.

(Second Embodiment) FIGS. 9 (a) and 9 (b) show an example in which a tilt is used with respect to the sub-scanning (paper feed) direction. This is often used when recording is performed at a density higher than the nozzle density, or when licking printing due to a time delay during ejection driving is corrected. For example, in the former case, with a head having a nozzle density of 360 dpi, 720 dpi
In order to record (P ₀ = 35.28 μm), α =
Tilt 60 degrees. At this time, each nozzle group interval P ₂
Is P ₂ = P ₀ × (n + m) / cos α = 35.28 × (24 + 8) / cos 60 ° = 2257.92 μm.

In the latter case, for example, 360 dpi (P ₀ =
(70.56 μm) recording, with this number of nozzles, it is sufficient to tilt about 3.5 °, and P ₂ is P ₂ = 70.56 × (24 + 8) / cos 3.5 ° = 2226.13 μm Becomes

The nozzle pitch P ₁ in the above example is appropriately set according to the relationship between the dot of the 24th nozzle of the a scan and the dot of the 1st nozzle of the (a + 1) scan under the condition that P ₁ cos α> P ₀ is satisfied. Just set it.

[0039]

As described above, according to the present invention, since the seams of each color are arranged at equal intervals, the density unevenness is less noticeable. Then, it is possible to prevent white stripes at the joints of the monochromatic bands. Furthermore, since the colors can be accurately superimposed, a high-quality color image can be obtained at a minimum cost.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a head according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of recording according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of recording according to the first embodiment of the present invention.

FIG. 4 is a circuit diagram of a first embodiment of the present invention.

FIG. 5 is a perspective view showing a recording apparatus to which the present invention can be applied.

FIG. 6 is a head mechanism diagram to which the present invention is applicable.

FIG. 7 is a schematic configuration diagram of a head and a carriage according to the first embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of a head according to the first embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of a head according to a second embodiment of the present invention.

FIG. 10 is a schematic configuration diagram of a conventional recording apparatus.

[Explanation of symbols]

 1 Yellow Head 2 Yellow Nozzle Discharge Port Group 3 Magenta Head 4 Magenta Nozzle Discharge Port Group 5 Cyan Head 6 Cyan Nozzle Discharge Port Group 7 Carriage 11 Recording Head 12 Yellow Nozzle Discharge Port Group 13 Magenta Nozzle Discharge Port Group 14 Cyan nozzle ejection port group 15 Black nozzle ejection port group

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B41J 2/13 G06K 15/00 B41J 3/04 103 B 104 D

Claims (4)

[Claims] 1. A plurality of color inks are ejected from a plurality of ejection part groups corresponding to the plurality of ejection parts and are arranged on the same straight line to record a band of each color on a recording medium. In an inkjet recording apparatus that completes recording by repeating, assuming that the basic recording pitch is P ₀ , the ejection unit pitch and the number are P ₁ and n, and the interval between ejection units at the same end of each ejection unit group is P ₂ . An inkjet recording apparatus, wherein P ₁ > P ₀ P ₂ = P ₀ × (n + m) (m is an integer). 2. The ink jet recording apparatus according to claim 1, wherein the integer m is an integral multiple of 8. 3. A configuration in which the arrangement direction of the ejection portions is inclined with respect to the paper feed direction, where the inclination angle is α, P ₁ cos α> P ₀ P ₂ = P ₀ × (n + m) / cos α (m is 2. The ink jet recording apparatus according to claim 1, wherein 4. The ink jet recording apparatus according to claim 1, wherein each ink is ejected from each of the ejection parts by thermal energy.