JPH0858083A - Method and device for ink jet printing - Google Patents

Abstract

PURPOSE: To carry out a high-speed reciprocating printing without lowering the printing quality by a method wherein, in the case of the printing by reciprocating scanning, a satellite is controlled to place in the region of main dote in both forward and return scanning. CONSTITUTION: In the printing of a picture using a multi-head 102 wherein the ink discharge direction is inclined to the return scanning direction of the arrow X2 with respect to an opening face 222, the scanning speed V2 in the return scanning direction of the arrow X2 is made lower than the scanning speed in the reverse forward scanning direction by CPU to reduce the shift distance L between a main dot D1 and a satellite D2 upon the return scanning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printing method and apparatus for performing reciprocal printing on an object to be printed such as print paper by reciprocally scanning an ink jet head.

[0002]

2. Description of the Related Art Conventionally, for example, a personal computer terminal,
Printers such as thermal transfer, laser beam, dot impact, and inkjet systems are used as output devices for copying machines or facsimiles.

In such a printer, the ink jet method has been attracting attention as a printing method which is excellent in quietness. Particularly, the one which ejects ink by utilizing the foaming of ink by heating has high print density and It has attracted attention as a high-quality and inexpensive printing method because it has excellent features such as easy colorization, excellent quietness, and endurance of high-speed printing.

Further, as the printing speed increases, ink jet heads having a plurality of ejection ports arranged, that is, those having a multi-head are generalized, and those having a plurality of the above-mentioned multi-heads for color are also developed. There is.

FIG. 8 shows an example of the construction of a printer section for printing on paper using the above-mentioned multi-head.

In FIG. 8, 101 is a total of four cartridges. These are four colors (black, cyan,
It is composed of an ink tank filled with each of magenta and yellow) color inks and a multi-head 102 provided for each ink tank. Ink ejection holes formed in each multi-head 102 are formed in the number of n along the Y direction in FIG. 8, and n ink ejection holes in each of the four multi-heads 102 are formed in the X direction in FIG. It is formed so as to be offset and aligned in parallel. The ink ejection holes in the four multi-heads may be formed, for example, so as to be arranged in parallel in the X direction in FIG. 8 with some inclination. In this case,
Each nozzle ejects ink while shifting the timing to perform printing. Further, in FIG. 8, reference numeral 103 denotes a paper feed roller, which rotates together with the auxiliary roller 104 in the direction of an arrow in FIG.
Is fed in the Y direction (conveying direction). Further, 105 is a pair of paper feed rollers, which rotate in the direction of the arrow in FIG. 8 to feed the print paper 107 while pinching it. 10
Reference numeral 6 denotes a carriage that supports four cartridges 101, which reciprocate along the arrow X direction during a printing operation.
In addition, when not printing, or the multi-head 1
When performing the recovery work of 02, etc., it stands by at the home position h shown by the dotted line in FIG.

Before the start of printing, the carriage 106 is at the home position h indicated by the dotted line in FIG. Then, in response to the print start command, the ink ejection holes 221 of the respective nozzles of each multi-head 102 are moved while moving in the X direction (scanning direction).
Ink is selectively ejected from the printing paper 10
1 of the formation width of n ink ejection ports 221 on the paper surface of No. 7
Print lines. In this way, when the printing of the data for one line is completed up to the edge of the printing paper 107,
The carriage 106 moves in the direction opposite to the X direction and returns to the original home position h. After that, the carriage 106 moves again in the X direction to print the next one line. In the case of performing reciprocal printing, printing is also performed when the carriage 106 moves in the direction opposite to the X direction.
In either case, the paper feed roller 103 rotates in the direction of the arrow after the printing of one line is completed and before the printing of the next line is started, and the printing width of one line is printed. The paper 107 is fed in the Y direction. In this way, by repeating printing for one line and paper feeding,
Printing of the data on one surface of the printing paper 107 is completed.

In the following, in the case where the multi-head 102 is scanned in the direction of arrow X _{1 in} FIG. 8 to start printing from the home position h side, the forward scanning is performed, and the multi-head 102 is printed to print toward the home position h. Is scanned in the direction of the arrow X _{2 in} FIG.

Further, by using such a printing apparatus,
When printing is performed only in the forward scan, one of the factors that hinders high-speed printing is that the backward scan becomes a completely useless scan. Therefore, in order to increase the speed, an attempt has been made to perform reciprocal printing by using the backward scan for printing.

By the way, when printing such as printing with an ink jet printing apparatus, in addition to the main dots ejected from the ink ejection holes and landing on the paper surface, the ink separated from the main droplets of the ink forming the main dots. Droplets land on the surface of the paper, forming small dots.
This small dot is called a "satellite." The small droplets that form this satellite were originally ejected at the same time as the main droplet, and the tension between the main droplet and the liquid surface of the meniscus of the ink ejection hole causes a tail portion on the rear side of the main droplet, The tail portion is separated due to surface tension to become a spherical shape. Therefore, it is considered that the droplets forming the satellite are more affected by the rearward action due to the surface tension when separated from the meniscus of the ink ejection hole than the main droplet, and the ejection speed is higher than that of the main droplet. slow.

Further, when the printing surface of the printing paper 107 and the opening surface where the ink ejection holes are opened are parallel, the positional relationship between the main droplets having different ejection speeds and the small droplets forming the satellites is uniform. It is constant as long as possible, and quality change is unlikely to occur in reciprocal printing except when there is a significant temperature rise.

However, when the ink ejection holes are inclined and opened with respect to the opening surface, a partial difference occurs in the affinity of the ink with respect to the opening surface, and the ejection direction of the droplets forming the satellite is changed. Change. A method for controlling the position of satellites by utilizing such a property has been proposed (see, for example, Japanese Patent Publication No. 5-43510). In the case of unidirectional printing, the speed is slower than that of the main droplet, and it is possible to store the droplets that have a deviation in the ejection direction (small droplets that form satellites) in the main dots on the printing surface. Met. The same applies when the opening surface is made of a different material in the scanning direction. That is, at the ink ejection port,
By using a material that has a high affinity for ink as a component on the side opposite to the scanning direction, it is possible to control the ejection direction of droplets that form satellites, as in the case of tilting the opening surface as described above. Becomes

As a structure of the multi-head 102 in which the ink ejection holes 221 are inclined with respect to the opening surface, there are, for example, those shown in FIGS.

The former multi-head 102 (see FIGS. 9 to 11)
(Refer to FIG. 3) is composed of the roof 21, the heater board 23, and the combination with the orifice plate 25. As shown in FIG. 11, the top 21 has an ink supply port 211, an ink reservoir (common liquid chamber) 212, and a plurality of ink flow paths 21.
3 are formed. On the heater board 23, heaters (electrothermal conversion elements) 231 located in the respective ink flow paths 213, and wirings 232 for individually energizing and heating the heaters 231 are formed. In addition, the orifice plate 25 has ink ejection holes 221 corresponding to the respective ink flow paths 213. 22
Reference numeral 2 denotes an opening surface of the ink ejection hole 221.

In such a multi-head 102, as a method for easily manufacturing the multi-head 102, the roof 21
There is a method of forming the ink discharge hole 221 after integrally molding the and orifice plate 25. However, in the case of such a manufacturing method, it is difficult to form the ejection holes 221 perpendicularly to the opening surface 222, so that the roof 2
The discharge holes 221 are formed from the upper side in FIG. However, even if the discharge holes 221 are formed in this way, it is difficult to avoid that the discharge holes 221 are slightly inclined with respect to the opening surface 222.

The multi-head 102 shown in FIGS.
In the above, the ink supplied into the ink reservoir 212 is supplied into the ink flow path 213 by the capillary phenomenon, and is stably held by forming a meniscus in the ink ejection hole 221. Then, the heater 23 is provided through the wiring 232.
By energizing No. 1, the ink on the heater 231 is heated, and a bubbling phenomenon due to film boiling occurs in the ink, and the energy of the bubbling causes the ink ejection hole 221.
A droplet of ink is ejected from.

On the other hand, in the latter head 102 of FIG. 12, the opening surface 222 is inclined in the forward scanning direction (arrow X ₁ direction), and as a result, the ink ejection holes 221 are opened obliquely with respect to the opening surface 222. are doing.

As described above, even if the ink ejection holes 221 are opened with being inclined with respect to the opening surface 222 in the forward scanning direction (arrow X ₁ direction) or the backward scanning direction (arrow X ₂ direction), they are unidirectional. In the case of printing, as described above, by controlling the ejection direction of the droplets forming the satellite, the satellite can be reduced and the print quality can be maintained.

[0019]

However, when performing printing such as printing by reciprocal scanning, in one-direction scanning, the ejection direction of droplets forming satellites is controlled to obtain a good image with few satellites. Although it can be obtained, in the reverse scanning in the other direction, the ejection direction of the droplets forming the satellite is opposite to the scanning direction, so that there is a problem that many satellites are generated and the image quality is deteriorated. .

[0020]

SUMMARY OF THE INVENTION It is an object of the present invention to, when printing is performed by reciprocal scanning, by storing satellites in main dots in both forward and backward scanning, high-speed reciprocal printing without degrading print quality. An object of the present invention is to provide an inkjet printing method and an apparatus therefor capable of realizing the above.

[0021]

The first aspect of the present invention is as follows.
When an ink jet head having an ink ejection port for ejecting ink and an opening surface where the ink ejection port is opened is used, when reciprocatingly scanning the ink jet head to perform reciprocal printing on an object to be printed, An ink jet printing method in which the ink ejection direction is inclined to either the forward scanning direction or the backward scanning direction of the ink jet head, and the ink jet head is scanned in the inclination direction of the ink ejected from the ink ejection port. In the ink jet printing method, the scanning speed of the ink jet head is set to be slower than that when scanning in the opposite direction.

Here, it is effective that the ink ejection holes are opened obliquely with respect to the opening surface. Also,
The opening surface may be formed of a material having a different affinity for ink, or may be inclined in either the forward scanning direction or the backward scanning direction of the inkjet head.
Further, it is preferable that the inkjet head is provided with a plurality of ones that eject different inks, and electrothermal conversion that generates thermal energy that causes film boiling in the ink as energy used for ejecting the ink. It may have an element.

On the other hand, the second aspect of the present invention uses an ink jet head having an ink ejection port for ejecting ink and an opening surface where the ink ejection port opens, and the ink jet head is reciprocally scanned to print. An inkjet printing apparatus in which, when performing reciprocal printing on an object, an ink ejection direction is inclined with respect to the opening surface in either one of a forward scanning direction and a backward scanning direction of the inkjet head, When scanning the inkjet head in the inclination direction of the ejected ink,
The inkjet printing apparatus further includes a scanning speed control unit that makes the scanning speed of the inkjet head slower than when scanning in the opposite direction.

Here, it is effective that the ink ejection holes are opened obliquely with respect to the opening surface. Also,
The opening surface may be formed of a material having a different affinity for ink, or may be inclined in either the forward scanning direction or the backward scanning direction of the inkjet head.
Further, it is preferable that the inkjet head is provided with a plurality of ones that eject different inks, and electrothermal conversion that generates thermal energy that causes film boiling in the ink as energy used for ejecting the ink. It may have an element.

[0025]

According to the present invention, the reciprocating scanning speed is changed by the scanning speed control unit according to the inclination of the ink discharging direction with respect to the opening surface where the ink discharging hole is opened.

For example, in the case of printing a single color image, it is possible to improve the image quality by reducing the increase in area factor due to satellites, suppressing the density difference in bidirectional printing, and reducing the unevenness of vertical lines. And Further, when a color image is printed, changes in area factor due to satellites are reduced, and high-quality images with less color unevenness are obtained by reciprocal printing.

[0027]

EXAMPLE An example of an ink jet printing apparatus capable of realizing the ink jet printing method according to the present invention will be described in detail with reference to FIGS.

[First Embodiment] In this embodiment, the multi-head 1 is equipped with a printer unit having the same configuration as that shown in FIG.
02, with respect to the opening surface where the ink ejection holes are opened,
The multi-head 102 was reciprocally scanned to print a single color of black ink by using the ink ejection holes having the inclination in the backward scanning direction. The multi-head 10
For example, in FIG. 9 to FIG. 11 described above, the top plate 21 and the orifice plate 25 are integrally formed, and the ink ejection hole 221 is inclined with respect to the opening surface 222 in the backward scanning direction. Or the above-mentioned FIG. 1
In the second example, the one in which the opening surface 222 is inclined can be used. Further, the portion of the opening surface where the ink ejection port 221 opens along the scanning direction of the multi-head 102 may be formed of different materials.

In FIG. 1, which shows a block of a control system in the printing apparatus of this embodiment, a CPU 100 executes control processing and data processing of the operation of each section of this apparatus.
The ROM 100A stores the processing procedure and the like, and the RAM 100B is used as a work area for executing the above processing.

Ink ejection from the multi-head 102
The CPU 100 supplies the drive data and drive control signal of the heater 231 to the head driver 1A. Further, the CPU 100 causes the carriage 106 (see FIG.
The rotation of the carriage motor 20 for moving the sheet feeding motor 50 and the rotation of the paper feed motor 50 for rotating the conveying rollers 103, 104, 105 are respectively controlled by the motor driver 20A.
And 50A. Furthermore, the CPU 100
As described later, configures a scanning speed control unit for controlling the rotation speed of the carriage motor 20 so as to change the scanning speed according to the scanning direction of the multi-head 102.

In this embodiment, the scanning speeds of the forward scan and the backward scan are changed as in Experimental Examples 1, 2, and 3 shown in Table 1 below to perform monochromatic printing, and the distance L between the main dot and the center of gravity of the satellite is L.
Was measured. In those experimental examples, the scanning speed at the backward scanning was set to be slower than that at the forward scanning, and the comparison was made with Comparative Examples 1 and 2 having the same scanning speed. The driving frequency of the multi-head 102, that is, the ejection frequency of the ink droplets ejected from the multi-head 102 also changes according to the scanning speed. In this example, the driving of the multi-head 102 of 360 dpi (dot / inch) is performed. The scanning speed when the frequency is 6 kHz corresponds to 42.3 cm / s, and similarly, when the driving frequency is 5 kHz, 4 kHz, 3 kHz, and 2 kHz, the scanning speeds are 35.3 cm / s and 28. 2 cm / s, 21.
It becomes 2cm / s and 14.1cm / s.

[0032]

[Table 1]

In the above table, Tmax is the maximum reached temperature (° C.) of the multi-head, and ΔOD25 is the result of measuring the difference in black density between the print results of the forward scan and the backward scan at 25% duty.

As is apparent from Table 1, in the experimental example in which the backward scanning speed is slower than the forward scanning speed as compared with the comparative example in which the reciprocating scanning speed is equal, the distance between the main dot and the satellite during the forward scanning is increased. The difference between the distance L and the distance L between them during the backward scanning becomes small. Therefore, as will be described later, vertical line irregularities due to satellites are reduced, and high-quality printing of characters, meridians, and the like becomes possible. In addition, the density change due to the increase of the area factor due to the satellite was also improved. Furthermore, as a side effect, excessive temperature rise of the multi-head 102 was suppressed, and it was possible to prevent density unevenness and deterioration of dot landing accuracy due to a decrease in ink viscosity.

FIG. 2A shows the positional relationship between the main dots D ₁ and the satellites D ₂ formed in the forward scanning in the above experimental example 1, and FIG. 3 shows the positional relationship between them in the backward scanning. A vertical line shown in (a) and printed by repeating these reciprocating scans is shown in FIG. 3 (b). FIG. 3 (b)
, W is the print width for one line, and the length is 5 times the width W (5 ×
The vertical line of W) was printed. Note that FIG. 2B shows a print example of vertical lines when only the forward scan in this experimental example is repeated five times.

FIG. 4 (a) shows the positional relationship between the main dots D ₁ and the satellites D ₂ formed during the backward scanning in the above-mentioned Experimental Example 2, and FIG. 4 (b) shows the reciprocating movement of the Experimental Example 2. Shows vertical lines printed by scanning.

FIG. 5 (a) shows the positional relationship between the main dots D ₁ and the satellites D ₂ formed during the backward scan of the above Comparative Example 1, and FIG. Shows vertical lines printed by scanning.

As is clear from FIGS. 2 to 5,
By making the scanning speed during the backward scan (when scanning in the direction in which the ink ejection direction is inclined) slower than during the forward scan, the unevenness of the vertical lines to be printed is reduced, and the image quality is improved.

FIGS. 6 (a) and 6 (b) show the positional relationship between the main dot D ₁ and the satellite D ₂ during the backward scan in the direction of the arrow X _{2. In} FIG. 6 (a), the scanning speed V ₂ is It is relatively large, and the scanning speed V ₂ is set relatively small in FIG. In these figures, V _D1 is the ejection speed of the main droplet forming the main dot D ₁ , V _D2 is the ejection speed of the small droplet forming the satellite D ₂ , and the latter droplet is the ejection speed V _D2.
Is smaller than the ejection speed V _D1 of the former main droplet, and the ejection direction deviates from the former main droplet due to the influence of the affinity of the ink with the opening surface 222 of the multi-head 102.
After all, when the scanning speed V ₂ is large, if the distance L between the main dot D ₁ and a satellite D ₂ as shown in the FIGS. 6 (a) is increased, the scanning speed V ₂ small, the The distance L between them becomes small as shown in FIG.

FIG. 7 shows the relationship between the main dot D ₁ and the satellite D ₂ during the forward scan in the direction of the arrow X _1. The influence of the distance L due to the change in the scanning speed V ₁ is that during the backward scan in FIG. Small compared to the case.

[Second Embodiment] In the present embodiment, the carriage 106 is the multi-head 102 in the first embodiment described above, that is, the multi-head 102 in which the ink ejection direction with respect to the opening surface is inclined in the backward scanning direction. (See Figure 8)
Three multi-colors were mounted on each of the above, and cyan (C), magenta (M), and yellow (Y) ink droplets were ejected from each multi-head 102 to perform multi-color printing. Then, the scanning speeds V ₁ and V ₂ of the forward scan and the backward scan are changed as shown in Experimental Examples 4 and 5 in Table 2 below to perform multicolor printing, and the main dot D ₁ and the satellite D ₂ are placed between the centers of gravity. The distance L was measured. In those experimental examples, the scanning speed V ₂ in the backward scanning was made slower than that in the forward scanning, and the scanning speeds V ₁ and V ₂ were compared to Comparative Example 3.

[0042]

[Table 2]

In the above table, ΔE is the result of measuring the difference in color density between the print results of the forward scan and the backward scan at 25% duty.

As is apparent from Table 2, in the experimental example in which the backward scan speed V ₂ is slower than the forward scan speed V ₁ as compared with the comparative example in which the reciprocating scan speeds V ₁ and V ₂ are equal, the forward scan is performed. The distance L between the main dot D ₁ and the satellite D ₂ at time,
The difference from the distance L between them during the backward scan becomes small. Therefore, as will be described later, vertical line irregularities due to the satellite D ₂ are reduced, and high-quality printing of characters, meridians, and the like becomes possible. Further, the change in color density due to the increase in area factor due to the satellite D ₂ was also improved. Further, as a side effect, the multi-head 10
The excessive temperature rise of 2 was suppressed, and it was possible to prevent density unevenness due to a decrease in ink viscosity and deterioration of dot landing accuracy.

In the above-described embodiment, the ink jet apparatus using the electrothermal conversion element for generating heat energy as the energy generating element has been described in order to achieve the high density and high definition of the print, but the piezoelectric element or the like is used. It can also be applied to an inkjet device using an electromechanical conversion element.

Regarding the typical constitution and principle of the ink jet device using the electrothermal converting element and the laser light described above,
For example, US Pat. No. 4,723,129 and US Pat.
What is done using the basic principles disclosed in the '740796 specification is preferred. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet holding the ink or the ink path. By applying at least one drive signal to the electrothermal converter, which corresponds to the print information and causes a rapid temperature rise exceeding nucleate boiling, thermal energy is generated in the electrothermal converter, and the thermal action of the inkjet head is generated. This is effective because film boiling is generated on the surface, and as a result, bubbles in the ink that correspond one-to-one to this drive signal can be formed. The growth and contraction of the bubbles cause the ink to be ejected through the ejection openings to form at least one droplet. It is more preferable to make this drive signal into a pulse shape, because the bubble growth and contraction are immediately and appropriately performed, so that it is possible to discharge the ink with excellent responsiveness. As the pulse-shaped drive signal, those described in US Pat. No. 4,463,359 and US Pat. No. 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124, which is an invention relating to the temperature rise rate of the heat acting surface, are adopted, more excellent printing can be performed.

As the constitution of the ink jet head, in addition to the combination constitution of the ejection port, the ink passage and the electrothermal converter (the linear ink passage or the right angle ink passage) as disclosed in the above-mentioned respective specifications. U.S. Pat. No. 4,558, which discloses a configuration in which a heat-acting portion is arranged in a bending region.
The present invention also includes configurations using the specification No. 333 and the specification of US Pat. No. 4,459,600. in addition,
Disclosed is a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters.
Japanese Patent Laid-Open No. 23670/1984, which discloses a structure in which an opening for absorbing a pressure wave of thermal energy is made to correspond to a discharge portion.
The effect of the present invention is effective even with a configuration based on Japanese Patent No. 138461. That is, according to the present invention, printing can be surely and efficiently performed regardless of the form of the inkjet head.

In addition, even in the case of the serial type as in the above example, an ink jet head fixed to the apparatus main body,
Alternatively, a replaceable chip-type inkjet head that can be electrically connected to the device body and supply ink from the device body by being attached to the device body, or an ink tank integrated with the inkjet head itself The present invention is also effective when the cartridge type inkjet head described above is used.

Further, as the constitution of the printing apparatus of the present invention, it is preferable to add the ejection recovery means of the ink jet head, the preliminary auxiliary means and the like because the effects of the present invention can be further stabilized. Specifically, heating is performed by using capping means, cleaning means, pressurizing or suctioning means, an electrothermal converter, or a heating element other than this, or a combination thereof for the ink jet head. Examples thereof include a preheating means for performing the preheating and a preejection means for performing the ejection different from the printing.

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

In addition, in the above-described embodiments of the present invention, the ink is described as a liquid, but an ink that solidifies at room temperature or lower and that softens or liquefies at room temperature may be used. Or, in the inkjet method, it is common to control the temperature of the ink itself within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within the stable ejection range. Sometimes, a liquid ink may be used. In addition, in order to positively prevent the temperature rise due to thermal energy as the energy of the state change from the solid state of the ink to the liquid state, or to prevent the evaporation of the ink, it solidifies and heats in the standing state. You may use the ink liquefied by. In any case, the ink is liquefied by the application of heat energy according to the print signal, and the liquid ink is ejected, or the one that has already started to solidify when it reaches the print medium,
The present invention is also applicable to the case of using an ink which has a property of liquefying only when heat energy is applied. The ink in such a case is described in JP-A-54-56847,
As described in JP-A-60-71260, a configuration may be used in which the electrothermal converter is opposed to the electrothermal converter in the state of being held as a liquid or solid in the recessed portions or through holes of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as a form of the ink jet printing apparatus of the present invention, besides the one used as an image output terminal of an information processing apparatus such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function. It may be a form or the like.

[0053]

According to the present invention, the reciprocating scanning speed is changed according to the inclination of the ink ejection direction with respect to the opening surface where the ink ejection holes are opened. Therefore, for example, when printing a single color image. By reducing the increase in area factor due to satellites, it is possible to suppress the density difference in reciprocal printing, and it is possible to improve image quality such as reducing vertical line irregularities. Also,
When printing a color image, it is possible to reduce changes in area factor due to satellites and obtain a high-quality image with little color unevenness by reciprocal printing.

Moreover, the excessive temperature rise of the ink jet head, which has been a problem in the conventional reciprocal printing system, can be suppressed at the same time, and the color unevenness and the difference in shade due to the temperature rise of the ink jet head can be reduced. By lowering the operating temperature, it is possible to extend the life of the inkjet head portion more than ever before.

[Brief description of drawings]

FIG. 1 is a block diagram of a control system in a first embodiment of the present invention.

FIGS. 2A and 2B are conceptual diagrams showing the positional relationship between main dots and satellites formed during forward scanning in Experimental Example 1 of the first embodiment of the present invention.

3 (a) and 3 (b) are conceptual diagrams showing the positional relationship between main dots and satellites formed during backward scanning in Experimental Example 1 of the first embodiment of the present invention.

FIGS. 4A and 4B are conceptual diagrams showing the positional relationship between main dots and satellites formed at the time of backward scanning in experimental example 2 in the first embodiment of the present invention.

5 (a) and 5 (b) are conceptual diagrams showing the positional relationship between main dots and satellites formed in the backward scan of Comparative Example 1 in the first embodiment of the present invention.

6A and 6B are conceptual diagrams showing the relationship between the backward scan speed of the inkjet head and the dot formation position in the first embodiment of the present invention.

FIG. 7 is a conceptual diagram showing the relationship between the forward scanning speed of the inkjet head and the dot formation position in the first embodiment of the present invention.

FIG. 8 is a perspective view showing a configuration example of a printer of an inkjet printing apparatus.

FIG. 9 is a perspective view showing a configuration example of an inkjet head.

FIG. 10 is an exploded perspective view of the inkjet head shown in FIG.

11 is a perspective view from the back surface side of the top shown in FIG.

FIG. 12 is a perspective view showing another configuration example of the inkjet head.

[Explanation of symbols]

1A Head driver 20 Carriage motor 20A Motor driver 21 Top plate 25 Orifice plate 50 Paper feed motor 50A Motor driver 100 CPU 100A ROM 100B RAM 102 Multihead 103-105 Conveying roller 106 Carriage 221 Ink ejection hole 222 Opening surface 231 Heater L Main dot Distance between satellite and satellite D ₁ Main dot D ₂ Satellite V _D1 Main droplet ejection speed V _D2 Small droplet ejection speed V ₁ , V ₂ Multi-head scanning speed

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B41J 2/51 2/485 19/18 A B41J 3/04 103 N 3/10 101 G 3/12 G (72 ) Inventor Shigetasu Nagoshi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hitoshi Sugimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Miyuki Matsubara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Fumihiro Goto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (12)

[Claims] 1. An ink jet head having an ink ejection port for ejecting ink and an opening surface for opening the ink ejection port is used, and when the ink jet head is reciprocally scanned to perform reciprocal printing on an object to be printed, An inkjet printing method in which an ink ejection direction inclines to either the forward scanning direction or the backward scanning direction of the inkjet head with respect to the opening surface, wherein the inkjet is applied in the inclination direction of the ink ejected from the ink ejection port. An inkjet printing method, wherein the scanning speed of the inkjet head is set to be slower when scanning the head than when scanning in the opposite direction. 2. The ink jet printing method according to claim 1, wherein the ink ejection hole is opened obliquely with respect to the opening surface. 3. The opening surface is formed of a material having a different affinity for ink.
Alternatively, the inkjet printing method according to claim 2. 4. The ink jet printing method according to claim 1, wherein the opening surface is inclined in one of a forward scanning direction and a backward scanning direction of the inkjet head. 5. The inkjet printing method according to claim 1, wherein the inkjet head includes a plurality of inkjet heads that eject different inks. 6. The ink jet head has an electrothermal conversion element that generates heat energy that causes film boiling in the ink, as energy used for ejecting the ink. The inkjet printing method described in any one of 1. 7. An ink jet head having an ink ejection port for ejecting ink and an opening surface for opening the ink ejection port is used, and when the ink jet head is reciprocally scanned to perform reciprocal printing on an object to be printed, An inkjet printing apparatus in which an ink ejection direction inclines to either one of a forward scanning direction and a backward scanning direction of the inkjet head with respect to the opening surface, wherein the inkjet is in an inclination direction of ink ejected from the ink ejection port. An inkjet printing apparatus comprising: a scanning speed control unit that slows the scanning speed of the inkjet head when scanning the head in the opposite direction. 8. The ink jet printing apparatus according to claim 7, wherein the ink ejection holes are formed obliquely with respect to the opening surface. 9. The opening surface is formed of a material having a different affinity for ink.
Alternatively, the inkjet printing apparatus according to claim 8. 10. The ink jet printing apparatus according to claim 7, wherein the opening surface is inclined in one of a forward scanning direction and a backward scanning direction of the ink jet head. 11. The inkjet printing apparatus according to claim 7, wherein the inkjet head includes a plurality of inkjet heads that eject different inks. 12. The ink jet head according to claim 7, wherein the ink jet head has an electrothermal conversion element that generates heat energy that causes film boiling in the ink as energy used for ejecting the ink. The inkjet printing apparatus described in any one of the above.