JP2003266740A - Liquid ejection head and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a suction recovery process on a liquid discharge head that discharges a single liquid from a plurality of discharge port groups having mutually different total opening areas of discharge ports, resulting in poor efficiency. Wastes liquid, wastefully. SOLUTION: A single liquid supply port 18 to which liquid is supplied.
A plurality of branch supply pipes 17a and 17b each having one end communicating with the liquid supply port 18;
A plurality of common liquid chambers 16a and 16b communicating with the other end sides of 7a and 17b, respectively; and a plurality of discharge ports communicating with these common liquid chambers 16a and 16b via liquid paths and discharging droplets respectively. Group, and the passage cross-sectional area and the passage length of the branch supply pipe 17a communicating with the ejection port group having a large total opening area of the ejection ports are determined by the total value of the opening area of the ejection ports. Is set smaller than the passage cross-sectional area and the passage length of the branch supply pipe 17b communicating with the discharge port group having a small diameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid ejection head, a suction recovery method thereof, a head cartridge incorporating the liquid ejection head, and an image forming apparatus using the liquid ejection head.

[0002] The "print" described in the present specification is not limited to the case of forming meaningful information such as characters and figures, but is also manifested so that it can be visually perceived by humans regardless of significant intent. It also includes the case where an image, a pattern, a pattern, or the like is widely formed on a print medium, or the print medium is processed by etching or the like regardless of whether it is a materialized product.

The "print medium" is not only a paper piece used in a general printing apparatus but also a liquid such as cloth, resin film, metal plate, glass, ceramics, wood, and leather, which can receive liquid. It also includes three-dimensional solids other than sheet-like objects, such as spheres and cylinders.

The term "liquid" is to be broadly interpreted in the same way as the definition of "print", and when applied to a print medium, it forms an image, a pattern, a pattern, etc., and a print medium such as etching. Or a treatment of ink, for example, a liquid that can be used for solidifying or insolubilizing a coloring material in the ink applied to the print medium, and includes all liquids used for printing.

[0005]

2. Description of the Related Art In an ink jet printer, when the entire apparatus is not used for a long period of time, or when a specific ejection port among a large number of ejection ports is liquid, that is, ink and / or If the treatment liquid is not discharged to adjust the printability of the ink on the print medium, the liquid may be defective.
The reason is that the water vaporizes in the ejection port and the liquid path communicating with the ejection port, and the viscosity of the ink increases. In addition, on the ejection surface of the inkjet head provided with the ejection port,
In some cases, water droplets, dust, or the like adheres, and the ejected droplets are pulled by these adherents and the ejection direction is deflected.

In order to prevent these problems, the conventional ink jet printer has the following means as a so-called ejection recovery device. For example, a pre-ejection unit that ejects liquid to a predetermined liquid receiving medium to remove thickened ink before printing work, or liquid suction that removes adhering substances by sucking liquid from an ejection port or a common liquid chamber. Means, liquid suction means for eliminating bubbles mixed in when replacing the liquid tank, and capping means for preventing evaporation of liquid moisture from the discharge port.

On the other hand, in an ink jet printer capable of printing a color image, in addition to black ink, a plurality of color ink ejection openings for yellow ink, magenta color ink and cyan color ink are provided in one ink jet head. An apparatus has been developed in which a group is provided, and each ejection port group is provided with an independent ink tank and an ink supply system, and each ejection port group is provided with a common recovery cap and ejection recovery means. In this type of inkjet printer, a color print image other than black is often composed of two or three colors. In this case, if the ejection amount of the color ink per dot is made equal to the ejection amount of the black ink, the diameter of the ink dot printed on the print medium such as paper becomes too large. Therefore, for color inks, the ejection port diameter is reduced, or the cross-sectional area of the liquid flow path communicating with the ejection port is changed. In the so-called bubble jet (registered trademark) method, in which droplets are discharged by heating an electrothermal converter or the like, a method of reducing the area of the electrothermal converter or changing the distance between the electrothermal converter and the ejection port. Is also adopted. Similarly, in an inkjet printer that uses a plurality of types of ink with different shades, a plurality of ejection port groups are formed in the same inkjet head or head cartridge, and the diameter and liquid of each ejection port of each ejection port group are also formed. The cross-sectional area of the flow path is changed.

[0008]

In recent years, in order to improve the quality and printing speed of a printed image, the technique of the ink jet head for multicolor ink or dark and light ink as described above is used, and a plurality of opening areas are different from each other. An ink jet head configured to eject a common ink from the ejection port group is considered.

A liquid supply port through which liquid is supplied, a branch supply path whose one end side communicates with this liquid supply port, a common liquid chamber which communicates with the other end side of these branch supply paths, and these common liquid chambers. When performing a suction recovery process on a liquid ejection head including a ejection port group that communicates via a liquid path and ejects droplets, an ejection port group having a large total opening area of ejection ports, When liquid is simultaneously sucked from the discharge port group having a small total opening area of the discharge ports, generally, a larger amount of liquid is sucked from the discharge port group having a larger total opening area of the discharge ports. Have a tendency.

Further, when the volumes of the individual liquid passages communicating with the respective discharge port groups are all about the same, the amount of liquid to be discharged at the time of suction recovery is also the same, so that the opening area of the discharge port is reduced. If the suction recovery process is performed in accordance with the discharge port group with the smaller total value, the result is that the required amount of liquid is excessively sucked and discharged from the discharge port group with the larger total opening area of the discharge ports. Therefore, there is a problem that the liquid is wastefully consumed.

Further, in the case where a liquid tank in which a porous body for holding a liquid such as a sponge is incorporated, and the amount of the liquid sucked and discharged is different for each tank,
There was a problem that air bubbles were taken into the flow path to which a liquid tank with a large discharge amount was connected.

[0012]

It is an object of the present invention to, when liquid is collectively sucked from a plurality of discharge port groups having different flow path resistances for each discharge port group, the amount of liquid sucked from each discharge port group. It is to provide a liquid ejection head in which the liquid ejection heads are close to each other or close to each other.

It is another object of the present invention to efficiently suck liquid when collectively sucking liquid from a plurality of discharge port groups having different discharge port configurations for each discharge port group. It is an object of the present invention to provide a liquid ejection head capable of preventing bubbles from being taken into the flow path while suppressing wasteful liquid consumption.

Still another object of the present invention is to efficiently suck liquid when collectively sucking liquid from a plurality of discharge port groups of a liquid discharge head having different discharge port configurations for each discharge port group. A suction recovery method capable of preventing the intake of air bubbles into the flow path while suppressing wasteful liquid consumption, and a head cartridge incorporating a liquid ejection head capable of realizing such a suction recovery method, and An object is to provide an image forming apparatus.

[0015]

The first aspect of the present invention is as follows.
One end side is connected to the liquid supply port to which the liquid is supplied, and a branch supply path is branched from the middle to form a plurality of branch paths, and a plurality of common liquid chambers that are respectively connected to the plurality of branch paths of the branch supply path. A liquid ejection head that includes a plurality of opening groups that respectively communicate with these common liquid chambers via a liquid path and that respectively open to the atmosphere, wherein:
The sectional area of the branch passage communicating with the opening group having the larger total area of openings is smaller than the sectional area of the branch passage communicating with the opening group having the smaller total value. Is.

According to a second aspect of the present invention, one end side communicates with a liquid supply port to which a liquid is supplied, and a branch supply path is branched from the middle to form a plurality of branch paths, and the plurality of branch supply paths. A liquid ejection head comprising: a plurality of common liquid chambers that respectively communicate with the branch passages; and a plurality of opening groups that respectively communicate with these common liquid chambers through liquid passages and that respectively open to the atmosphere, Of the opening group, the length of the branch path communicating with the opening group having the larger total area of the openings is,
It is characterized in that it is longer than the length of the branch passage communicating with the opening group having the smaller total value.

According to a third aspect of the present invention, one end side communicates with a liquid supply port through which liquid is supplied, and a branch supply path is branched from the middle to form a plurality of branch paths, and the plurality of branch supply paths. A liquid ejection head comprising: a plurality of common liquid chambers that respectively communicate with the branch passages; and a plurality of opening groups that respectively communicate with these common liquid chambers through liquid passages and that respectively open to the atmosphere, Of the opening group, the branch position of the branch path in the branch supply path communicating with the opening group with the larger total area of the openings is the branch position in the branch supply path communicating with the opening group with the smaller total value. It is characterized in that it is on the downstream side with respect to the flow direction of the liquid than the branch position of the branch passage.

According to a fourth aspect of the present invention, one end side communicates with a liquid supply port through which liquid is supplied, and a branch supply path is branched from the middle to form a plurality of branch paths, and the plurality of branch supply paths. A liquid ejection head comprising: a plurality of common liquid chambers that respectively communicate with the branch passages; and a plurality of opening groups that respectively communicate with these common liquid chambers through liquid passages and that respectively open to the atmosphere, Are arranged adjacent to the plurality of ejection openings arranged at a predetermined interval for ejecting liquid onto the print medium and the ejection openings located at the end in the arrangement direction, and are used for forming an image on the print medium. It is characterized by having an opening group consisting of liquid discharge ports that are not involved and an opening group consisting only of the discharge ports.

A fifth aspect of the present invention is provided with a plurality of opening groups which respectively communicate with a plurality of common liquid chambers via liquid paths and which are open to the atmosphere, and these opening groups are arranged at predetermined intervals. Liquid ejection having a plurality of ejection openings for ejecting liquid onto the print medium and a liquid ejection opening arranged adjacent to the ejection openings located at the end portion in the arrangement direction and not involved in image formation on the print medium In the head, among the plurality of opening groups, the number of the liquid discharge ports included in the opening group having the larger total value of the areas of the ejection ports is the opening of the one having the smaller total value of the areas of the ejection ports. It is characterized in that the number is smaller than the number of the liquid discharge ports included in the group.

A sixth aspect of the present invention is provided with a plurality of opening groups each communicating with a plurality of common liquid chambers via liquid passages and opening to the atmosphere, and these opening groups are arranged at predetermined intervals. Liquid ejection having a plurality of ejection openings for ejecting liquid onto the print medium and a liquid ejection opening arranged adjacent to the ejection openings located at the end portion in the arrangement direction and not involved in image formation on the print medium In the head, of the plurality of opening groups, the total value of the areas of the liquid discharge ports included in the opening group having the larger total value of the areas of the discharge ports is smaller than the total value of the areas of the discharge ports. It is characterized in that it is smaller than the total value of the areas of the liquid discharge ports of one opening group.

According to a seventh aspect of the present invention, one end side communicates with a liquid supply port to which liquid is supplied, and a branch supply path is branched from the middle to form a plurality of branch paths, and the plurality of branch supply paths. A plurality of common liquid chambers respectively communicating with the branch passages, and a plurality of head portions each having a plurality of opening groups respectively communicating with the common liquid chambers through the liquid passages and opening to the atmosphere, all the openings A liquid ejection head in which the number of openings of at least one opening group among the groups is different from the number of openings of other opening groups, and the total opening area of all the opening groups is the largest. The total value of is less than or equal to 1.6 times the total value of the opening group having the smallest total area of the openings, and the total area of the openings forming the plurality of opening groups among the plurality of head portions is The total value of the head part with the maximum total value is the surface of the opening. The total value of the products is less than or equal to 5 times the total of the minimum head portion.

According to an eighth aspect of the present invention, one end side communicates with a liquid supply port to which a liquid is supplied, and a branch supply path is branched from the middle to form a plurality of branch paths, and the plurality of branch supply paths. A first head portion having a plurality of common liquid chambers that respectively communicate with the branch passages, and a plurality of opening groups that respectively communicate with these common liquid chambers through the liquid passages and that respectively open to the atmosphere; A common liquid chamber communicating with the liquid supply port, and a second head unit having a group of openings communicating with the common liquid chambers via liquid paths and opening to the atmosphere, respectively. A liquid discharge head in which the number of openings in at least one of the opening groups is different from the number of openings in the other opening groups, and the total sum of the area of the openings is the largest among all the opening groups. The total value of the group is the total value of the opening area The total value is 1.6 times or less of the total value of the smallest opening group, and the total value of the head portions having the largest total area of the openings forming the opening group among the first and second head sections. Is characterized in that the total value of the area of the openings is 5 times or less than the total value of the minimum head portion.

According to a ninth aspect of the present invention, one end side communicates with a liquid supply port to which a liquid is supplied, and a branch supply path is branched from the middle to form a plurality of branch paths, and the plurality of branch supply paths. A plurality of common liquid chambers respectively communicating with the branch passages, and a plurality of head portions each having a plurality of opening groups respectively communicating with the common liquid chambers through the liquid passages and opening to the atmosphere, all the openings At least one opening group of the groups is a liquid ejection head having at least one opening having an area different from that of another opening group, and the total value of the opening areas of all the opening groups is maximum. The total value of the opening groups is less than or equal to 1.6 times the total value of the opening group having the smallest total area of the openings, and the openings forming the plurality of opening groups among the plurality of head portions are Of the head area with the maximum total area The total value is characterized in that the total value of the area of the openings is 5 times or less of the total value of the minimum head portion.

According to a tenth aspect of the present invention, one end side communicates with a liquid supply port to which a liquid is supplied, and a branch supply path is branched from the middle to form a plurality of branch paths, and the plurality of branch supply paths. A first head portion having a plurality of common liquid chambers that respectively communicate with the branch passages, and a plurality of opening groups that respectively communicate with these common liquid chambers through the liquid passages and that respectively open to the atmosphere; A common liquid chamber communicating with the liquid supply port, and a second head unit having a group of openings communicating with the common liquid chambers via liquid paths and opening to the atmosphere, respectively. At least one opening group among the opening groups is a liquid ejection head having at least one opening having an area different from the openings of other opening groups, and the total value of the opening areas among all the opening groups is The total value of the largest opening group , The total area of the openings is less than or equal to 1.6 times the total of the minimum opening group, and the total area of the openings forming the opening group in the first and second head portions is The total value of the maximum head portion is characterized in that the total value of the area of the openings is not more than 5 times the total value of the minimum head portion.

The eleventh aspect of the present invention is the first to first aspects of the present invention.
A suction recovery method for maintaining a good discharge state of droplets from the opening group by collectively sucking the liquid from the opening group of the liquid discharge head according to any one of the tenth aspects. The feature is that the amount of liquid sucked from the opening group is made substantially equal.

The twelfth aspect of the present invention relates to the first to first aspects of the present invention.
A head cartridge comprising: a liquid ejection head according to any one of the tenth aspects; and a liquid tank that stores a liquid supplied to the liquid ejection head via a liquid supply port of the liquid ejection head. is there.

The thirteenth aspect of the present invention relates to the first to first aspects of the present invention.
An image is formed on a print medium by the liquid ejected from the plurality of ejection port groups of the liquid ejection head according to any one of the tenth aspects or the plurality of ejection port groups of the liquid ejection head of the head cartridge according to the twelfth aspect of the present invention. An image forming apparatus for forming a liquid ejecting head or a head cartridge, a print medium conveying unit, and an ejection port surface on which a plurality of ejection port groups of the liquid ejection head are opened. It is characterized by comprising a cap member capable of being sucked and a suction recovery unit capable of sucking the liquid interposed in the liquid discharge head from the plurality of discharge port groups via the cap member.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION In the liquid discharge head according to the first to sixth aspects of the present invention, at least one of the plurality of opening groups has a different number of openings from the other opening groups. You may Alternatively, among the plurality of opening groups, at least one opening group may have at least one opening having an area different from that of another opening group.

In the liquid ejection head according to any one of the first to third and seventh to tenth aspects of the present invention, a plurality of ejection openings for arranging the openings at predetermined intervals to eject the liquid onto the print medium. And a liquid discharge port which is arranged adjacent to the discharge port located at the end in the arrangement direction and which does not participate in the formation of an image on the print medium.

In the liquid ejection head according to any one of the first to tenth aspects of the present invention, the opening group may be collectively covered with a common cap and suction may be applied.

A liquid tank for storing the liquid can be connected to the liquid supply port, and the liquid tank may have a porous body for holding the liquid.

A discharge energy generating portion for discharging a droplet from the opening can be provided in the liquid path. In this case, the discharge energy generating section may have an electrothermal converter that generates thermal energy for causing film boiling in the liquid.

In the liquid ejection head according to the third aspect of the present invention, there may be three or more opening groups.

In the liquid ejection heads according to the fifth and sixth aspects of the present invention, the plurality of common liquid chambers have one end communicating with the liquid supply port to which the liquid is supplied, and branch from the middle to form a plurality of branch passages. The plurality of branch supply paths may communicate with the plurality of branch paths.

In the liquid discharge heads according to the seventh to tenth aspects of the present invention, the total value of the opening group having the largest total area value of the openings and the total value of the opening group having the smallest total area value of the openings. The values may be almost equal.

In the liquid discharge heads according to the ninth and tenth aspects of the present invention, the number of openings of at least one opening group among all the opening groups is different from the number of openings of other opening groups. Good.

In the head cartridge according to the twelfth aspect of the present invention, the liquid tank may be removable from the liquid ejection head.

In the image forming apparatus according to the thirteenth aspect of the present invention, the mounting portion may include a carriage that can scan and move in a direction intersecting the print medium transport direction. In this case, the liquid ejection head may be detachably mounted on the carriage via the attaching / detaching means.

The liquid may be a treatment liquid for adjusting the printability of the ink on the ink and / or the print medium.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the image forming apparatus according to the present invention is applied to a serial scan type ink jet printer will be described in detail with reference to FIGS. 1 to 15. However, the present invention is not limited to such an embodiment. However, they may be further combined and applied to other techniques that are to be included in the inventive concept as claimed in this specification.

FIG. 1 shows a schematic structure of the ink jet printer in this embodiment. That is, the carriage 11
Is a plurality of inks for facing the print surface of a print medium such as a print sheet (not shown) conveyed on the platen 12 and ejecting a treatment liquid for adjusting the printability of the ink on the print medium. The head cartridge 13 in which the ejection port groups 19A and 19B (see FIG. 3) are formed is detachably held by a detaching means (not shown). The carriage 11 is connected to a part of a drive belt 15 that transmits a driving force of a head drive motor 14, and a head cartridge 13 in which a liquid tank (not shown) is replaceably mounted is reciprocally scanned over the entire width of a print medium. It is possible to move it.

Head cartridge 13 in this embodiment
The schematic structure of the main part of the
The front shape of the discharge port plate is shown in FIG. That is, a plurality (two in the illustrated example) of branch supply that respectively form a branch supply path is provided at one end of each of the plurality (two in the illustrated example) of common liquid chambers 16a and 16b of the head cartridge 13 in the present embodiment. One ends of the pipes 17a and 17b communicate with each other, and the other ends of the branch supply pipes 17a and 17b are connected to each other,
It communicates with one liquid supply port 18 to which the liquid is supplied. On the other end side of the common liquid chambers 16a, 16b, a plurality of liquid passages (not shown) and a plurality of discharge outlet groups 19A, 19B respectively communicating with these liquid passages are formed on the discharge outlet surfaces 20a, 20b (in the illustrated example, 2). Liquids supplied from the liquid supply port 18 are attached to the discharge port plates 21a and 21b
Droplets are ejected as droplets from the individual ejection ports 19a, 19b through the respective liquid passages through the bifurcated branch supply pipes 17a, 17b to enter the common liquid chambers 16a, 16b. The ejection port plate 21a for ejecting large droplets, in which the diameter of each ejection port 19a that constitutes the ejection port group 19A and the volume of the liquid path that communicates therewith is large, and 19b of each ejection port that constitutes the ejection port group 19B. The ejection port plate 21b for ejecting small droplets, which has a small diameter and a small volume of a liquid path communicating with this, has 128 ejection ports 19a and 19b arranged at intervals of 600 dpi in this embodiment. The diameter of each discharge port 19a is set to 16 μm, and the diameter of each discharge port 19b is set to about 10 μm. The volume of each droplet discharged from the discharge opening 19a for discharging large droplets is about 4 picoliters, and the volume of each droplet discharged from the discharge opening 19b for discharging small droplets is about 2 picoliters. Is set to.

In this embodiment, each discharge port group 19A,
A total of 16 discharge ports 19a ′, 1 located from the both ends to the fourth position along the arrangement direction of 19B, respectively.
Reference numeral 9b 'is a dummy ejection port that is not involved in image formation, that is, a liquid ejection port, and these liquid ejection ports 19a' and 19b '.
From the above, it functions so that the bubbles that are likely to be present at both ends of the ejection port groups 19A and 19B in the arrangement direction are eliminated by the suction recovery operation.

The ejection recovery device 22 for the head cartridge 13 is arranged at one end of the scanning movement path of the head cartridge 13, for example, at a position facing the home position, and the mechanical transmission mechanism 24 is driven by the driving force of the recovery motor 23. The cap member 25 is capped on the ejection port surfaces 20a and 20b of the head cartridge 13 via the cap member 25. In connection with the capping of the head cartridge 13 by the cap member 25 of the ejection recovery device 22, a liquid suction operation by a suction means (not shown) incorporated in the ejection recovery device 22 or a liquid supply path to the head cartridge 13 is incorporated. The liquid is pressure-fed by a pressurizing means (not shown), and the liquid is discharged to the individual discharge ports 19a,
By forcibly discharging from the discharge port 19b, the discharge port 19
A discharge recovery process is performed to remove liquids such as thickened ink that are present in the liquid passages a and 19b and liquid passages that communicate with a and 19b. Further, when the printing operation is completed, the cap members 25 collectively cover the ejection port surfaces 20a and 20b in a hermetically sealed state to protect the ejection port surfaces 20a and 20b of the head cartridge 13.

FIG. 4 shows the appearance of the above-mentioned cap member 25, and FIG. 5 shows the capping state of the head cartridge 13 by the cap member 25 in a sectional view. That is, inside the cap member 25, a porous or fibrous waste ink absorber 26 for absorbing and retaining the liquid droplets remaining in the cap member 25 is arranged so as to face the waste ink absorber 26. A suction port 27 is opened at the end, and a suction pipe 28 is connected thereto. The cap member 25 comes into close contact with the ejection port surfaces 20a and 20b of the head cartridge 13 during non-printing work, and prevents the liquid from evaporating from the ejection ports 19a and 19b.
Further, the head cartridge 13 is left for a long period of time, and the ejection ports 19a and 19b, the liquid paths, and the common liquid chambers 16a and 16b are
When the viscosity of the internal liquid increases, when air bubbles are mixed into the liquid passages or the common liquid chambers 16a and 16b from the outside, or when invading air bubbles are removed from the connecting portion when the liquid tank 29 is replaced, etc. , Head cartridge 1
3 is pressed against the discharge port surfaces 20a and 20b and sucked by a suction pump (not shown) to perform discharge recovery processing.

In the present embodiment, the cross-sectional area of the passage of the branch supply pipe 17a communicating with the discharge port 19a for discharging large droplets described above is changed to the passage of the branch supply pipe 17b communicating with the discharge port 19b for discharging small droplets. It is set smaller than the cross-sectional area by, for example, about one half. With such a configuration, the total value of the areas of the ejection ports 19a forming the ejection port group 19A is large, and conventionally, the ejection port for ejecting large liquid droplets in which the liquid discharge flow rate at the time of suction recovery is relatively large. While the flow path resistance on the side of the group 19A becomes relatively large, the total value of the areas of the discharge ports 19b that make up the discharge port group 19B is small, and in the past, the liquid discharge flow rate at the time of suction recovery is relatively small. Since the flow path resistance on the ejection port group 19B side for ejecting droplets is relatively small, the amount of liquid ejected at the time of suction recovery is reduced to the ejection port group 19A side for ejecting large droplets and the ejection amount for small droplet ejection ports. It can be brought closer to the outlet group 19B side, and it becomes possible to suppress wasteful discharge of liquid at the time of suction recovery.

In this embodiment, although the passage cross-sectional area of the branch supply pipe 17a communicating with the large-droplet discharge outlet group 19A is set to be uniform, the cross-sectional area is partially reduced. Can also obtain the same effect.

A flexible wiping blade 30 made of ether urethane or the like is disposed on the side of the discharge recovery device 22 and held by a blade holding member 31.
The wiping blade 30 is operated by the recovery motor 17 and the mechanical transmission mechanism 24 described above similarly to the ejection recovery device 22, and the tip end portion thereof can be in sliding contact with the ejection port surfaces 20a and 20b of the head cartridge 13. Becomes As a result, liquid mist or dust adhering to the ejection port surfaces 20a and 20b of the head cartridge 13 can be wiped off at an appropriate timing during the printing operation of the head cartridge 13 or after the ejection recovery process using the ejection recovery device 22. The blade 30 is projected into the moving path of the head cartridge 13 so that liquid mist, dust or the like attached to the ejection port surfaces 20a and 20b of the head cartridge 13 can be wiped off as the head cartridge 13 scans and moves to the home position side. It has become.

In the above-mentioned embodiment, the two branch supply pipes 1
Although the passage cross-sectional areas of 7a and 17b are changed from each other, the same effect can be obtained by changing the passage lengths of these.

FIG. 6 shows a cross-sectional structure of another embodiment of the liquid discharge head according to the present invention. Members having the same functions as those of the previous embodiment are designated by the same reference numerals, and redundant description will be repeated. Shall be omitted. That is, in this embodiment, the branch supply pipe 1 that communicates with the ejection opening group 19A for ejecting large droplets.
The passage length of 7a is set to be, for example, about twice as long as the passage length of the branch supply pipe 17b communicating with the ejection opening group 19B for ejecting small droplets. With such a configuration, the flow path resistance on the side of the ejection opening group 19A for ejecting large droplets, in which the total area of the ejection openings 19a is large and the liquid discharge flow rate at the time of suction recovery usually tends to be large. Is relatively large, whereas the total value of the areas of the discharge ports 19b is small, and the liquid discharge flow rate during suction recovery usually tends to be small. Since the path resistance is relatively small, the amount of liquid discharged at the time of suction recovery can be made nearly the same on the ejection opening group 19A side for ejecting large droplets and the ejection opening group 19B side for ejecting small droplets. You can
It becomes possible to suppress the wasteful discharge of the liquid at the time of suction recovery.

In the above-described embodiment, the two discharge port groups 19
Since the number of discharge ports 19a and 19b forming A and 19B is the same, it was necessary to change the passage cross-sectional area and the passage length of the branch supply pipes 17a and 17b. However, the common liquid chamber 16b for discharging small droplets is required. By arranging a large number of liquid discharge ports communicating with the discharge port 19b adjacent to the discharge port 19b, it is possible to obtain substantially the same effect as that of the above-described embodiment.

A cross-sectional structure of another embodiment of the liquid discharge head according to the present invention is shown in FIG. 7, and the front shape of the discharge port surface thereof is schematically shown in FIG. 8. The same function as in the previous embodiment is shown. The same symbols are given to the members of FIG. 3 and the duplicated description will be omitted. That is, in the present embodiment, the branch supply pipe 17a communicating with the ejection opening group 19A for ejecting large droplets.
Further, the passage cross-sectional area and the passage length of the branch supply pipe 17b communicating with the ejection opening group 19B for ejecting small droplets are both set to be the same. In the ejection port plate 21b in which the ejection port group 19B for ejecting small droplets in the present embodiment is formed, a liquid ejection port group 19C not involved in image formation is arranged along the ejection port group 19B. The number, size, and the like are set to be substantially the same as those of the individual ejection ports 19b. In this embodiment, 128 discharge ports 19b and liquid discharge ports 19b ', 19c' are arranged at 600 dpi intervals, and the diameter is set to about 12 μm. Further, 128 ejection ports 19a for ejecting large droplets are arranged at 600 dpi intervals, and the diameter is set to about 17 μm. With such a configuration, the ejection port 1 for ejecting small droplets
9b and the liquid discharge ports 19b ′ and 19c ′, the total value of the areas is used as the discharge port 19a and the liquid discharge port 19 for discharging large liquid droplets.
Since it can be made substantially equal to the total value of the areas of a ′, the amount of liquid discharged from the discharge port group 19A side at the time of suction recovery and the amount of liquid discharged from the discharge port group 19B and the liquid discharge port group 19C side. Are equal, and efficient suction recovery processing can be performed.

The area and size of the liquid discharge port 19c 'constituting the liquid discharge port group 19C may be other than those in the above-described embodiment, and the area of the discharge port 19b for discharging small droplets and the liquid discharge port 19b' may be changed. Ejection port 19a for ejecting large droplets with a total value
The closer to the total value of the areas of the liquid discharge ports 19a ', the more the effect according to the object of the present invention can be obtained. It is also possible to incorporate a discharge energy generation unit in the liquid passage communicating with the liquid discharge port 19c 'constituting the liquid discharge port group 19C so that the liquid droplet discharge operation can be performed as necessary.
Discharge port 19b for discharging small droplets and liquid discharge port 19b ', 1
When the total area of 9c ′ cannot be matched with the total area of the ejection port 19a for discharging large liquid droplets and the liquid ejection port 19a ′, branching is performed as in the embodiment shown in FIGS. 5 and 6. It is also effective to change the passage cross-sectional area and passage length of the supply pipes 17a and 17b.

In the embodiment shown in FIG. 3, the liquid discharge ports 19 formed on the two discharge port plates 21a and 21b, respectively.
Although the dimensions and shapes of a ′ and 19b ′ are matched with the dimensions and shapes of the liquid outlets 19a and 19b in which they are formed, the dimensions and shape of the outlet plate 21a provided with the outlet group 19A for ejecting large droplets. While forming a small liquid discharge port, a large size liquid discharge port is formed on the discharge port plate 21b provided with the discharge port group 19B for discharging small liquid droplets. can do.

FIG. 9 shows the arrangement state of the ejection port groups of the liquid ejection head according to the present invention. Members having the same functions as those of the previous embodiment are designated by the same reference numerals, and the duplicate description will be omitted. It shall be omitted. That is, in the ejection port plate 21a on which the ejection port groups 19A for ejecting large droplets are formed, small liquid ejection ports 19a 'having a diameter and size of about 10 μm are formed at both ends of the ejection port group 19A in the arrangement direction. ing. On the contrary, on the ejection port plate 21b on which the ejection port groups 19B for ejecting small droplets are formed, large liquid ejection ports 19b 'having a diameter and size of about 16 μm are formed at both ends of the ejection port group 19B in the arrangement direction. Has been done. The size and shape of the liquid discharge port 19a 'in this embodiment are the same as the discharge port 19b for discharging small droplets.
The size and shape of the
The size and shape of b'is set to be substantially the same as the size and shape of the discharge port 19a for discharging large droplets. With such a configuration, the total value of the areas of the ejection openings 19a and the liquid ejection openings 19a 'for ejecting the large droplets and the areas of the ejection openings 19b and the ejection openings 19b' for the small droplet ejection openings can be calculated. Since it can be close to the total value, the discharge port group 19A can be recovered at the time of suction recovery.
The amount of liquid discharged from the side of the discharge port group 19B and the amount of liquid discharged from the side of the discharge port group 19B can be brought close to each other to perform efficient suction recovery processing.

The number and size of the liquid discharge ports 19a 'and 19b' are not limited to those in the above-described embodiment, and the total area of the discharge ports 19b for discharging small droplets and the liquid discharge port 19b '. Is a discharge port 19a for discharging a large droplet and a liquid discharge port 1
The closer to the total value of the areas of 9a ′, the more the effect according to the object of the present invention can be obtained. Further, the passage cross-sectional area and the passage length of the branch supply pipe 17a communicating with the discharge port group 19A for discharging large droplets and the branch supply pipe 17b communicating with the discharge port group 19B for discharging small droplets are shown in FIG. Similar to the previous embodiment, both can be set to the same value, but the passage cross-sectional area and the passage length may be changed if necessary.

In the above embodiment, the two discharge port plates 21
Liquid discharge ports 19a and 19 formed in a and 21b, respectively.
By appropriately setting the number and size of b, the amount of liquid sucked and discharged from the discharge port group 19A and the discharge port group 19A
Although the amount of the liquid sucked and discharged from B is made close to each other, the total value of the opening areas of the discharge ports 19a forming the discharge port group 19A of the discharge port plate 21a and the discharge ports 19b forming the discharge port group 19B. The object of the present invention can also be achieved to some extent by suppressing the difference from the total value of the opening areas of 1 to within a predetermined range.

FIG. 10 shows a partial sectional structure of such a liquid discharge head according to the present invention. However, members having the same functions as those in the previous embodiment are designated by the same reference numerals, and duplicate explanations are omitted. It shall be. That is, the ejection port group 19A for ejecting large liquid droplets is composed of four liquid ejection ports 19a ′ on one side and 128 ejection ports 19a on one side, which are located at both ends in the arrangement direction, and these are arranged in two rows. Common liquid chamber 1
6a. A branch supply pipe 17a (not shown) is connected to the common liquid chamber 16a via an ink supply port 32a. The diameters of the liquid discharge ports 19a ′ and the discharge ports 19a of the discharge port group 19A for discharging large droplets are set to 12 μm, and they are arranged at intervals of 300 dpi per row. In the present embodiment, the arrangement pitches of the two columns are shifted by a half pitch along the arrangement direction, so the apparent arrangement pitch of these two rows is 600 dpi. Similarly, the ejection port group 19B for ejecting small droplets is composed of four liquid ejection ports 19b ′ located at both ends in the arrangement direction and a total of 128 ejection ports 19b, which are also arranged in two rows. Common liquid chamber 16b
Is in communication with. A branch supply pipe 17b (not shown) is connected to the common liquid chamber 16b via an ink supply port 32b. The diameters of the liquid discharge ports 19b ′ and the discharge ports 19b that form the discharge port group 19B for discharging small droplets are set to 10 μm and are arranged at intervals of 300 dpi per row. In the present embodiment, the arrangement pitches of the two columns are shifted by a half pitch along the arrangement direction, so the apparent arrangement pitch of these two rows is 600 dpi.

Therefore, the total opening area of the ejection opening group 19A for ejecting large droplets is suppressed to about 1.4 times the opening area of the ejection opening group 19B for ejecting small droplets. This is 1.
If the difference is about 6 times or less, the liquid can be uniformly discharged from all the ejection port groups at the time of suction recovery, so that the ejection port groups 19A and 19B can be discharged from the ejection port groups 19A and 19B at the time of suction recovery of the present embodiment. It is possible to keep the difference in the suction amount of the liquid within the allowable range.

In the above-described embodiment, the head cartridge 13 in which the flow path is branched into two has been described, but the present invention can be effectively applied to a liquid ejection head in which the flow path is branched into three or more. it can.

FIG. 11 shows the cross-sectional shape of yet another embodiment of the liquid discharge head according to the present invention, and FIG. 12 shows the front shape of the discharge port surface thereof. Members having the same functions as those of the previous embodiment. The same reference numerals as those in FIG. That is, the head cartridge 13 according to the present embodiment includes the ejection port group 1 for ejecting large droplets.
An ejection port plate 21a having 9A, an ejection port plate 21d having an ejection port group 19D for ejecting medium droplets, and an ejection port plate 21b having an ejection port group 19B for ejecting small droplets are provided. Correspondingly, it has three common liquid chambers 16a, 16d, 16b and branch supply pipes 17a, 17d, 17b. Discharge ports 19a constituting each discharge port group 19A, 19D, 19B
The diameter of the discharge port is about 16 μm, the diameter of the discharge port 19d is set at about 10 μm, the diameter of the discharge port 19b is set at about 7 μm, and 128 discharge port rows are formed at intervals of 600 dpi. It is the same as in the previous embodiment that the discharge ports located at are liquid discharge ports 19a ', 19d', 19b ', respectively. Discharge ports 19a, 19
Droplets of 4 picoliters, 2 picoliters, and 1 picoliter are discharged from d and 19b, respectively.

In this embodiment, the branch supply pipes 17a, 1
The branch points of 7d and 17b are set to two, and the ratio of these lengths is set to about 1: 2: 4. However, even if these branch points are set to one, there is no particular problem. Absent. Further, these branch supply pipes 17a, 17d, 17b
The cross-sectional areas may be different at a ratio of, for example, 1: 2: 4.

With such a structure, the flow path resistance becomes relatively large on the side of the large droplet discharge port 19a where the total area of the discharge ports is large and the ink discharge flow rate at the time of suction recovery is large. On the other hand, the total value of the discharge area is small,
Small droplet discharge port 19 with low ink discharge flow rate during suction recovery
Since the flow path resistance becomes relatively smaller toward the b side, the amount of liquid discharged during suction recovery is such that the discharge port group 19A for discharging large liquid droplets,
As a result of the ejection opening group 19D for ejecting medium droplets and the ejection opening group 19B for ejecting small droplets approaching each other, it is possible to suppress wasteful discharge of liquid during suction recovery.

In the above-described embodiment, the head cartridge 13 for ejecting a single type of liquid or a single color of ink has been described. However, a head for recovering suction of a plurality of types or colors of ink using the same cap member. The present invention can be applied to a cartridge.

The disassembled structure of the liquid discharge head according to the present invention is shown in FIG. 13. The members having the same functions as those in the previous embodiment are designated by the same reference numerals, and the duplicated description will be omitted. And A black ink tank 29K for storing black ink, a cyan ink tank 29C for storing cyan ink, a magenta ink tank 29M for storing magenta ink, and a yellow ink tank 29Y for storing yellow ink. Each color ink supplied from 29 is connected to the connection portion 3 formed on the connection plate 33.
4K, 34C, 34M, 34Y and slit-shaped ink supply paths 36K, 36C formed in the flow path forming plate 35.
Passing through 36M and 36Y, individual common liquid chambers 16K and 16C
It is supplied to ₁ , 16C ₂ , 16M ₁ , 16M ₂ , 16Y.
In this embodiment, the cyan color ink supply path 36C and the magenta color ink supply path 36M are each branched into two to form a branch supply tube, and each of the two cyan liquid common liquid chambers 16C ₁ , 16C ₂ and the common liquid chambers 16M ₁ and 16M ₂ for magenta ink, a total of five common liquid chambers 16K, 16C ₁ and 16C ₂ ,
It is equipped with 16M ₁ , 16M ₂ and 16Y. These common liquid chambers 16K, 16C ₁ , 16C ₂ , 16M ₁ , 16M ₂ , 16
Y is provided with a color ink ejection port plate 21L corresponding to three colors other than black and a black ink ejection port plate 21K for black, and the ejection ports formed on these ejection port plates 21L and 21K. Droplets can be discharged from the outlet.

At the time of suction recovery, the color ink and the black ink can be sucked and discharged separately by independently operating the suction pumps (not shown) communicating with the color ink cap member 25L and the black ink cap member 25K. Has become.

FIG. 14 shows a sectional structure of a part of the liquid discharge head in this embodiment. In this liquid ejection head, the bidirectional printing, that is, when performing the printing operation both in the forward scanning and the backward scanning, the ejection order of the color ink is not changed between the forward scanning and the backward scanning of the liquid ejection head. Therefore, cyan ink ejection port arrays are provided on both sides in the scanning direction,
A discharge port array for magenta color ink is arranged inside thereof, and a discharge port array for yellow ink is arranged in the middle. The ejection port group 19E formed on the ejection port plate 21K for black ink includes four liquid ejection ports 19e ′ on one side and two liquid ejection ports 19e ′ on both sides in the arrangement direction.
It is composed of zero discharge ports 19e, and these are connected to the common liquid chamber 16K in a state of being arranged in two rows. These are arranged at an interval of 300 dpi per row, but the apparent arrangement pitch of the two rows is 600 because the arrangement pitch of the two rows is shifted by a half pitch along the arrangement direction.
The interval is dpi.

A yellow ink ejection port group 19F is formed in the center of the color ink ejection port plate 21L, and the magenta color ink ejection port groups 19G and 19H are formed of the yellow ink ejection port group 19F. The ejection port groups 21I and 19J for cyan ink are formed on the ejection port plate 21L for color ink so that the three ejection port groups 19F to 19J are sandwiched therebetween.
It is formed on both side ends of the color ink ejection port plate 21L so as to sandwich H.

Similar to the ejection port group 19E for black ink, the ejection port group 19F for yellow ink includes four liquid ejection ports 19f ′ on one side and 128 ejection ports 19f on one side, which are located at both ends in the arrangement direction. And is connected to the common liquid chamber 16Y in a state of being arranged in two rows. All of them have a diameter set to 16 μm and are arranged at intervals of 600 dpi per row, but the arrangement pitch of the two rows is shifted by half a pitch along the arrangement direction, so the apparent arrangement pitch of these rows is Is 1200 dpi.

Ejection port groups 19G, 1 for magenta ink
Ejection port groups 19I and 19J for 9H and cyan ink
Are 128 large-droplet discharge outlets 19g _L , 19h _L , 19i _L , 19j _L each having a diameter of 16 μm, and four liquid discharge outlets 19g connected to both ends in the arrangement direction.
_A row of _L ', 19h _L ', 19i _L ', 19j _L's arranged at 600dpi, and 128 small droplet discharge outlets 19g _S , 19h _S , 19i _S , 19j _S each having a diameter of 10 μm and Four liquid discharge ports 19g following both ends in the arrangement direction
_{S ', 19h S', 19i} S ', 19j S' is formed by two rows respectively between rows arranged in 600 dpi. In this _embodiment, the outlet groups for magenta ink are located on both sides of the discharge port group 19F for yellow ink 19G, 19H and outlet groups 19I for cyan ink, 19J, these sequences direction Since they are shifted by a half pitch along the line, the ejection port groups 19G, 1 for magenta color ink
Ejection port groups 19I and 19J for 9H and cyan ink
The apparent array pitch is 1200 dpi.
It should be noted that by not forming the small liquid droplet ejection port as the ejection port for the yellow ink, in which the granularity of the dots is less noticeable than the cyan color ink and the magenta color ink, all the ejection ports for the yellow ink are common. Since it can be housed in the liquid chamber, the manufacturing cost of the print head can be suppressed, and the scanning movement width can be shortened, so that the apparatus can be downsized.

With such a nozzle arrangement on the color side, with respect to the ejection port group 19F for yellow ink having the maximum total opening area, the total opening area has the minimum total opening area. It is suppressed to about 1.4 times the total value of the opening areas of the ejection port groups 19G to 19J for the magenta color ink and the cyan color ink. This is 1.6
If the difference is about twice or less, it is possible to uniformly discharge the liquid from all the ejection port groups at the time of suction recovery, and therefore, the difference in the suction amount of ink at the time of suction recovery of the present embodiment is within the allowable range. It can fit inside.

The number, size and shape of the discharge ports and the liquid discharge ports are not limited to those in the above-described embodiment, and the total value of the opening areas in the discharge port group having the maximum total opening area is The closer to the total value of the opening areas in the ejection port group having the smallest total area value, the more the effect according to the object of the present invention can be obtained. For this purpose,
It is also effective to appropriately change the lengths of the ink supply paths 36K, 36C, 36M and 36Y and the passage cross-sectional areas.

FIG. 15 shows a fracture structure of the main part of the above-mentioned color liquid discharge head. That is, the main part of the liquid ejection head in this embodiment has a thickness of 0.5 mm to 1.0.
The discharge energy generating portion, the common liquid chamber 16, the discharge port 19 and the like are formed on the silicon substrate 37 of mm by using the film forming technique. The ink supply passage 36 is formed through the silicon substrate 37. Long ink supply port 32 connected to
Are formed by anisotropic etching using the crystal orientation. On both sides of the ink supply port 32, a plurality of (128 in one side in this embodiment) electrothermal converters 38 arranged in two rows at predetermined intervals along the longitudinal direction of the ink supply port 32 are shifted by a half pitch. Are formed in a closed state, and each constitutes a discharge energy generating portion. On the silicon substrate 37, in addition to the electrothermal converters 38, bump-shaped connection terminals 39 and aluminum formed of gold or the like for electrically connecting the electrothermal converters 38 to an electric wiring board (not shown). The electric wiring and the like (not shown) are formed by a film forming technique, and the drive IC (not shown) and the electrothermal converter 38 are connected via these connection terminals 39.
To the electrothermal converter 38 at the same time.

The ink supply port 3 is provided on the silicon substrate 37.
A discharge port plate 2 having a plurality of discharge ports 19 that face the electrothermal converter 38 through a common liquid chamber 16 communicating with the discharge port plate 2.
1 is provided. That is, a liquid path communicating with each of the discharge ports 19 and the common liquid chamber 16 is formed between the discharge port plate 21 and the silicon substrate 37, and a partition wall 40 is formed between adjacent liquid paths. To be done. These common liquid chambers 16,
The liquid passage, the partition wall 40, and the like are formed together with the ejection port plate 21 by the photolithography technique, similarly to the ejection port 19.

In the above-described embodiment, the total value of the opening areas in the discharge port group having the maximum total opening area is
The case where the total value of the opening areas is close to the total value of the opening areas in the discharge port group having the smallest total value has been described, but the total value of the opening areas of one or more discharge port groups communicating with the same liquid tank is the maximum. The total value of the opening areas of the liquid ejection heads is such that the total value of the areas of one or a plurality of ejection port groups communicating with another same liquid tank is the minimum. 5 times or less, preferably close to or equal to the minimum total value, the liquid discharge amount from the liquid tank communicating with the liquid discharge head having the maximum total opening area of the discharge port group is satisfied. Since it is possible to prevent the air bubbles from becoming extremely large, it is possible to prevent a problem that air bubbles are taken into the flow path.
This effect is particularly remarkable in the case of a liquid ejection head that uses a liquid tank 29 in which a porous body such as a sponge that holds a liquid is stored.

The present invention comprises means (eg, electrothermal converter or laser light) for generating thermal energy as the energy used for discharging the liquid,
This thermal energy brings about excellent effects in an ink jet type liquid ejection head, a head cartridge, or an image forming apparatus that causes a change in the state of a liquid. This is because according to such a method, high density and high definition printing can be achieved.

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 applicable to both the so-called on-demand type and the continuous type, but in the case of the on-demand type in particular, the electrical device arranged corresponding to the sheet or flow path holding the liquid. Thermal energy is generated by applying at least one drive signal that gives a rapid temperature rise exceeding nucleate boiling corresponding to print information to the heat conversion element, and causes film boiling on the heat-acting surface of the liquid ejection head. As a result, bubbles can be formed in the liquid in a one-to-one correspondence with this drive signal, which is effective. By the growth and contraction of the bubbles, the liquid is ejected through the ejection port 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 the ejection of the liquid with excellent responsiveness can be achieved. 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 rate of temperature rise on the heat acting surface, are adopted, more excellent printing can be performed.

As the constitution of the liquid discharge head, the combination constitution of the discharge port, the liquid passage and the electrothermal converter as disclosed in the above-mentioned specifications (the electrothermal converter is arranged along the liquid passage is shown. U.S. Pat. No. 455, which discloses a configuration in which the heat-acting portion is arranged in a region in which the heat-acting portion is bent, in addition to the straight liquid passage or the electrothermal converter (a right-angled liquid passage that faces the discharge port with the liquid passage in between).
The present invention includes a configuration using the specification of 8333 and the specification of US Pat. No. 4,459,600. In addition, JP-A-59-59 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters.
Japanese Laid-Open Patent Publication No. 123670 and Japanese Patent Laid-open No. Sho 59-59, which discloses a configuration in which an opening for absorbing a pressure wave of thermal energy corresponds to a discharge portion.
The effect of the present invention is effective even with a configuration based on Japanese Patent Laid-Open No. 138461. That is, according to the present invention, it is possible to perform printing reliably and efficiently regardless of the form of the liquid ejection head.

Even in the case of the serial type as in the above-described embodiment, the liquid ejection head fixed integrally to the carriage which moves in scanning, or the carriage which is electrically attached to the carriage by being exchangeably mounted. When using a replaceable chip-in type head cartridge that enables various connections and supply of liquid from the device body, or a head cartridge in which a liquid storage head itself is provided with a tank that stores liquid in an integrated or replaceable manner Also, the present invention is effective.

As the constitution of the image forming apparatus of the present invention, it is preferable to add a preliminary auxiliary means for making the ejection state of the liquid from the liquid ejection head proper, because the effect of the present invention can be further stabilized. It is a thing. Specific examples thereof include cleaning means for the liquid ejection head, pressurizing means, preheating means for heating using an electrothermal converter, a heating element other than this, or a combination thereof, and a printing operation separately. Preliminary ejection means for ejecting may be mentioned.

Regarding the type and number of the liquid ejection heads to be mounted, for example, only one is provided corresponding to a single color ink, or a plurality of types of ink having different print colors and densities (brightness). A plurality of units may be provided correspondingly. That is, for example, as the print mode of the image forming apparatus, not only the print mode of only the mainstream color such as black but also the liquid discharge head is integrally configured,
The present invention is extremely effective for an image forming apparatus provided with at least one of full-color print modes of different colors of multiple colors or mixed colors, although a plurality of combinations may be used. In this case, it is also effective to eject the treatment liquid (printability improving liquid) for adjusting the printability of the ink onto the print medium from a dedicated or common liquid ejection head in accordance with the type of print medium and the print mode.

In the embodiment of the present invention described above,
A liquid that solidifies at room temperature or lower and softens or liquefies at room temperature may be used, or in the inkjet method, the temperature of the liquid itself is adjusted within the range of 30 ° C to 70 ° C to stabilize the viscosity of the liquid in a stable discharge range. Since the temperature control is generally performed as described in (1), a liquid state may be used when the use print signal is applied. 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 to the liquid state, or to prevent the liquid from evaporating, it is solidified in the standing state and liquefied by heating. You may use what does. In any case, it liquefies by applying heat energy according to the print signal, and liquefies only when heat energy is applied, such as those that eject liquid and those that already start to solidify when reaching the print medium. The present invention can be applied to the case of using a material having a property. In such a case, the liquid is retained as a liquid or solid in the recesses or through holes of the porous sheet as described in JP-A-54-56847 or JP-A-60-71260. Then, it may be configured to face the electrothermal converter. In the present invention, the most effective one for each of the above-mentioned liquids is to execute the above-mentioned film boiling method.

The form of the image forming apparatus according to the present invention is used as an image output terminal of information processing equipment such as a computer, a copying machine combined with a reader, a facsimile machine or a textile printing machine having a transmitting / receiving function. Alternatively, the print medium may be in the form of an etching device, and the print medium may be a sheet or a long paper or cloth, or a plate-like wood or leather,
In addition to stone materials, resins, glass, metals, etc., three-dimensional three-dimensional structures can be cited.

[0085]

According to the liquid discharge head of the present invention, among the plurality of opening groups, the opening having the smaller total value of the cross-sectional areas of the branch passages communicating with the opening group having the larger total area of the openings is opened. Make it smaller than the cross-sectional area of the branch path that communicates with the group, or set the length of the branch path that communicates with the opening group with the larger total area of the openings among the multiple opening groups with the smaller total value. If the length of the branch passage communicating with the opening group is made longer, or especially if the discharge port group has three or more groups, it is connected to the opening group having the larger total area of the openings among the plurality of opening groups. The branch position of the branch path in the branch supply path
The amount of liquid sucked from the ejection port group with a large total opening area of the ejection ports, because it is located downstream of the branch position of the branch channel in the branch supply path that communicates with the opening group with a small total value. And the amount of liquid sucked from the discharge port group having a small total opening area of the discharge ports can be brought close to each other, and wasteful discharge of liquid due to the suction recovery process can be suppressed.

According to the liquid discharge head of the present invention, the plurality of openings are arranged adjacent to the plurality of discharge openings arranged at a predetermined interval for discharging the liquid onto the print medium, and the discharge openings located at the ends in the arrangement direction. And an opening group consisting of liquid discharge ports that do not participate in the formation of an image on the print medium and an opening group consisting of only discharge ports, or the total area of the discharge ports of the plurality of opening groups. The number of liquid discharge ports of the opening group having the larger value is smaller than the number of liquid discharge ports of the opening group having the smaller total value of the discharge port areas, or among the plural opening groups, The total value of the area of the liquid discharge ports of the opening group with the larger total value of the discharge ports is smaller than the total value of the area of the liquid discharge ports of the opening group with the smaller total value of the discharge ports. Since it is small, the total value of the opening area of the discharge port is large. And the amount of liquid is sucked from the discharge port group, aspirated from the total value is smaller ejection orifice groups of the opening area of the discharge port is the liquid volume and can be made close almost good suction recovery processing efficiency can be performed.

When the number of openings of at least one opening group among the plurality of opening groups is different from the number of openings of other opening groups, a specific droplet is printed faster than the other droplets. can do. For example, by increasing the numerical aperture of the black ink opening group to be larger than that of the other cyan ink, magenta color ink, and yellow ink opening groups, it is possible to suppress the manufacturing cost of the print head and further, in monochrome printing. An increase in print speed can be achieved.

When the area of at least one opening of at least one opening group among the plurality of opening groups is made different from the area of the openings of the other opening groups, for example, a small liquid droplet ejection port and a large liquid droplet ejection port Is formed in each ejection port group for cyan ink and magenta color ink, and only the large droplet ejection port is formed in the ejection port group for yellow ink in which the ink droplets are less noticeable. Since it is not necessary to provide a small liquid droplet ejection port in the group, the manufacturing cost of the print head can be suppressed, and the ejection port group for cyan ink and magenta ink can eject ink droplets having different ejection amounts. Become. For this reason, it is possible to improve the printing speed by selecting dots to be ejected as appropriate, such as ejecting a large droplet in a high-duty image in which dots are not conspicuous and ejecting a small droplet in a low-duty image in which dots are conspicuous. It is possible to improve the image quality.

According to the liquid head of the present invention, among the opening groups of the plurality of head portions, the total value of the opening groups having the largest total opening area is calculated as the total value of the opening groups having the smallest total opening area. If the total value of the opening areas is less than or equal to 1.6 times the total value, and the total area value of the opening areas forming the opening group among the plurality of head areas is the maximum, Since it is 5 times or less than the total value of the opening area of the smallest head part, the amount of liquid sucked from the head part having the largest total opening area and the head part having the smallest total opening area are sucked. It is possible to make the amount of liquid to be made substantially close to each other, and it is possible to suppress wasteful discharge of liquid due to the suction recovery process.

When the number of openings in at least one opening group out of all the opening groups is different from the number of openings in the other opening groups, a specific droplet is printed faster than other droplets. can do. For example, the manufacturing cost of the print head can be suppressed by increasing the numerical aperture of the opening group for black ink to be larger than the numerical aperture of the opening groups for other cyan ink, magenta color ink, and yellow ink. Moreover, it is possible to improve the printing speed in monochrome printing.

When the total value of the opening group having the maximum total area value of the openings and the total value of the opening group having the minimum total area value of the openings are made substantially equal to each other, liquid sucked from them The suction amount of can be made almost equal.

A group of openings are arranged adjacent to the plurality of ejection openings arranged at a predetermined interval for ejecting liquid onto the print medium and the ejection openings located at the ends in the arrangement direction, and an image is formed on the print medium. In the case of having a liquid discharge port that does not participate in, for example, when the liquid discharge ports are provided at both ends of the discharge port group, bubbles that tend to stay at both ends of the common liquid chamber can be effectively removed from the liquid discharge port during suction recovery. .

When the openings are collectively covered with a common cap and suction is performed, the suction recovery process of the liquid discharge head can be efficiently performed.

A liquid tank which stores a liquid and has a porous body for holding the liquid usually has an air flow in the porous body holding the liquid when the flow rate of the liquid processed at the time of suction recovery is large. Although a passage is formed, bubbles are easily drawn into the ink flow path portion of the liquid ejection head, which may cause a problem of image deterioration. However, the liquid ejection head of the present invention can perform good suction recovery processing.

According to the suction recovery method of the present invention, when the liquid is collectively sucked from the plurality of ejection port groups of the liquid ejection head and the ejection state of the droplets from the plurality of ejection port groups is maintained in a good condition. Since the amounts of the liquids sucked from the respective ejection port groups are made substantially equal to each other, it is possible to suppress the wasteful discharge of the liquids accompanying the suction recovery process, and it is possible to perform the efficient suction recovery process.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic structure of an embodiment in which an image forming apparatus according to the present invention is applied to an inkjet printer.

FIG. 2 is an exploded perspective view showing a schematic structure of an embodiment of a print head used in the inkjet printer shown in FIG.

FIG. 3 is a schematic diagram illustrating an array state of ejection port groups of the print head illustrated in FIG.

FIG. 4 is a perspective view showing the outer appearance of a cap member used in the inkjet printer shown in FIG. 1 together with a print head.

5 is a cross-sectional view showing a capped state of the cap member shown in FIG.

FIG. 6 is a sectional view showing another embodiment of the liquid discharge head according to the present invention together with its cap member.

FIG. 7 is a sectional view showing another embodiment of the liquid discharge head according to the present invention together with its cap member.

8 is a schematic diagram showing an array state of ejection port groups of the liquid ejection head in the embodiment shown in FIG.

FIG. 9 is a schematic diagram showing an array state of ejection port groups in still another embodiment of the liquid ejection head according to the present invention.

FIG. 10 is a partial extraction cross-sectional view of still another embodiment of the liquid ejection head according to the present invention.

FIG. 11 is a cross-sectional view showing another embodiment of the liquid discharge head according to the present invention together with its cap member.

FIG. 12 is a schematic diagram showing an arrangement state of ejection port groups of the liquid ejection head in the embodiment shown in FIG.

FIG. 13 is an exploded perspective view of still another embodiment of the liquid ejection head according to the present invention.

FIG. 14 is a partially extracted cross-sectional view of the embodiment shown in FIG.

FIG. 15 is a perspective view showing an external appearance of a main part of the liquid ejection head in a broken state in the embodiment shown in FIG.

[Explanation of symbols]

11 Carriage 12 Platen 13 Head Cartridge 14 Head Drive Motor 15 Drive Belts 16a, 16b, 16d, 16K, 16C ₁ , 16C ₂ , 16M
₁ , 16M ₂ , 16Y Common liquid chamber 17a, 17b Branch supply pipe 18 Liquid supply ports 19A, 19B, 19D to 19J Discharge port group 19C Liquid discharge port group 19, 19a, 19b, 19e, 19f, 19g _{L to} 19j _L ,
19g _{S to} 19j _S Discharge ports 19a ', 19b', 19e ', 19f', 19g _{L to} 19j _L ',
19g _S ~19j _S 'liquid discharge ports 20a, 20b, 20e discharge port surface 21a, 21b, 21e, 21L, 21K discharge port plate 22 discharge recovering apparatus 23 recovers motor 24 mechanical transmission mechanism 25,25L, 25K cap member 26 Waste ink absorber 27 Suction port 28 Suction piping 29, 29K, 29C, 29M, 29Y Liquid tank 30 Wiping blade 31 Blade holding member 32, 32c ₁ , 32c ₂ , 32m ₁ , 32m ₂ , 32y Ink supply port 33 Connection plate 34K, 34C, 34M, 34Y Connection part 35 Flow path forming plate 36K, 36C, 36M, 36Y Ink supply path 37 Silicon substrate 38 Electrothermal converter 39 Connection terminal 40 Partition wall

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[Procedure amendment]

[Submission date] December 13, 2002 (2002.12.
13)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Liquid ejection head and image forming apparatus

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction content]

[0001]

The present invention relates to relates to an image forming apparatus which have use the liquid discharge head of the liquid discharge head Contact <br/> by Biko.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

Still another object of the present invention is to efficiently suck liquid when collectively sucking liquid from a plurality of discharge port groups of a liquid discharge head having different discharge port configurations for each discharge port group. it can, moreover there is provided an image forming apparatus using a waste liquid discharge head that obtained prevent entrapment of air bubbles in the liquid consumption to suppressing while the channel of.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Delete

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Delete

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

The 11th form of the present invention is the first to the first aspect of the present invention.
An image forming apparatus for forming an image on the 10th one of the print medium by the liquid ejected plurality of discharge port groups or these liquid ejection heads in the form of a mounting portion of the liquid ejection head or the head cartridge A print medium carrying means, a cap member capable of covering a discharge port surface of the liquid discharge head where a plurality of discharge port groups are opened, and the liquid discharge from the plurality of discharge port groups via the cap member. And a suction recovery means capable of sucking the liquid interposed in the head.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Delete

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

[0038] In the image forming apparatus according to a first 1 of the embodiment of the present invention, the mounting portion may be one having a direction allowing scanning movement carriage intersecting the transport direction of the print medium. In this case, the liquid ejection head may be detachably mounted on the carriage via the attaching / detaching means.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0095

[Correction method] Delete

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiichiro Takahashi             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Hitoshi Nishikori             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor, Iwasaki             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Minoru Teshigawara             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Satoshi Chikuma             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Satoshi Seki             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Hitoshi Sugimoto             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F term (reference) 2C056 EA01 EA25 EA27 EE14 FA02                       FA03 FA10 FC01 HA05 HA21                       HA60 JA01 JA13 JA17 JC06                       JC20 KB40 KC01 KC02 KC11                       KC22

Claims (28)

[Claims] 1. A branch supply path, one end side of which communicates with a liquid supply port to which a liquid is supplied, and which is branched from the middle to form a plurality of branch paths, and a plurality of communication paths which respectively communicate with the plurality of branch paths of the branch supply path. A common liquid chamber, and a plurality of opening groups that communicate with the common liquid chambers via liquid paths and that are open to the atmosphere, respectively. The liquid discharge characterized in that the sectional area of the branch passage communicating with the opening group having the larger total area is smaller than the sectional area of the branch passage communicating with the opening group having the smaller total value. head. 2. A branch supply path, one end side of which communicates with a liquid supply port to which a liquid is supplied, and which branches from the middle to form a plurality of branch paths, and a plurality of communication paths which respectively communicate with the plurality of branch paths of the branch supply path. A common liquid chamber, and a plurality of opening groups that communicate with the common liquid chambers via liquid paths and that are open to the atmosphere, respectively. The liquid ejection head is characterized in that the length of the branch passage communicating with the opening group having the larger total area is larger than the length of the branch passage communicating with the opening group having the smaller total value. . 3. A branch supply path, one end side of which communicates with a liquid supply port to which a liquid is supplied, and which branches from the middle to form a plurality of branch paths, and a plurality of communication paths which respectively communicate with the plurality of branch paths of the branch supply path. A common liquid chamber, and a plurality of opening groups that communicate with the common liquid chambers via liquid paths and that are open to the atmosphere, respectively. The branching position of the branching path in the branching supply path communicating with the opening group having a larger total value of areas is larger than the branching position of the branching path in the branching supply path communicating with the opening group having a smaller total value. A liquid ejection head, which is on the downstream side in the flow direction of the liquid. 4. The liquid ejection head according to claim 3, wherein there are three or more opening groups. 5. A branch supply path, one end side of which communicates with a liquid supply port to which a liquid is supplied, and which is branched from the middle to form a plurality of branch paths, and a plurality of communication paths which respectively communicate with the plurality of branch paths of the branch supply path. A common liquid chamber and a plurality of opening groups that communicate with the common liquid chambers via liquid paths and that are open to the atmosphere, respectively, wherein the plurality of opening groups are arranged at predetermined intervals. A plurality of ejection openings for arranging in order to eject the liquid onto the print medium, and a liquid ejection opening arranged adjacent to the ejection openings located at the end in the arrangement direction and not involved in the formation of an image on the print medium. And a group of openings including only the discharge ports. 6. A plurality of common liquid chambers, each of which communicates with each other through a liquid passage, and each of which has a plurality of openings which are open to the atmosphere. These openings are arranged at a predetermined interval to discharge the liquid onto a print medium. A liquid ejection head having a plurality of ejection ports for adhering to each other and a liquid ejection port which is arranged adjacent to the ejection ports located at an end in the arrangement direction and which does not participate in image formation on a print medium. The number of the liquid discharge ports included in the opening group having the larger total area value of the discharge ports is the liquid discharge port included in the opening group having the smaller total value area of the discharge ports. The liquid ejection head is characterized in that it is less than the number of. 7. A plurality of groups of openings, each of which communicates with a plurality of common liquid chambers via a liquid path and which is open to the atmosphere, are arranged at a predetermined interval to discharge a liquid onto a print medium. A liquid ejection head having a plurality of ejection ports for adhering to each other and a liquid ejection port which is arranged adjacent to the ejection ports located at an end in the arrangement direction and which does not participate in image formation on a print medium. Of the opening groups, the total value of the area of the liquid discharge ports of the opening group having the larger total value of the areas of the discharge ports is the same as that of the opening group having the smaller total value of the areas of the discharge ports. A liquid ejection head characterized by being smaller than the total value of the areas of the liquid discharge ports. 8. The plurality of common liquid chambers are respectively connected to the plurality of branch passages of a branch supply passage which is connected at one end side to a liquid supply port to which the liquid is supplied and which is branched from the middle to form a plurality of branch passages. The liquid ejection head according to claim 6 or 7, wherein 9. At least one of the plurality of aperture groups
The liquid ejection head according to claim 1, wherein one opening group has a different number of openings from the other opening groups. 10. The method according to claim 1, wherein at least one opening group among the plurality of opening groups has at least one opening having an area different from that of another opening group. The liquid ejection head according to claim 1. 11. A branch supply path, one end side of which communicates with a liquid supply port to which a liquid is supplied, and which is branched from the middle to form a plurality of branch paths, and a plurality of communication paths which respectively communicate with the plurality of branch paths of the branch supply path. And a plurality of head portions each having a plurality of opening groups communicating with the common liquid chambers via liquid paths and opening to the atmosphere, at least one of all the opening groups is provided. A liquid ejection head in which the number of openings of the opening group is different from the number of openings of other opening groups, and the total value of the opening groups having the largest total area of the openings among all the opening groups is Is less than or equal to 1.6 times the total value of the smallest opening group, and the largest total area value of the openings forming the plurality of opening groups among the plurality of head sections. The total value of the A liquid ejection head, which is 5 times or less the total value of the head portion. 12. A branch supply path, one end side of which communicates with a liquid supply port to which a liquid is supplied, and which is branched from the middle to form a plurality of branch paths, and a plurality of communication paths which respectively communicate with the plurality of branch paths of the branch supply path. Of the common liquid chamber, a first head portion having a plurality of opening groups respectively communicating with these common liquid chambers via liquid paths, and each opening to the atmosphere, and a liquid supply port to which the liquid is supplied. And a second head part having a common liquid chamber that communicates with the common liquid chambers via liquid paths and that has an opening group that respectively opens to the atmosphere. At least one of all the opening groups is provided. A liquid ejection head in which the number of openings in one opening group is different from the number of openings in another opening group, and the total value of the opening groups having the largest total area of the openings among all the opening groups is Equivalent to the group of openings with the smallest total area of openings. The total value is 1.6 times or less of the total value, and the total value of the head parts having the largest total area of the openings forming the opening group among the first and second head parts is A liquid ejection head, wherein the total value is 5 times or less of the total value of the minimum head portion. 13. A branch supply path, one end side of which communicates with a liquid supply port to which a liquid is supplied, and which is branched from the middle to form a plurality of branch paths, and a plurality of communication paths which respectively communicate with the plurality of branch paths of the branch supply path. A plurality of head parts each having a common liquid chamber and a plurality of opening groups that communicate with the common liquid chambers via liquid paths and that respectively open to the atmosphere, and at least one of all the opening groups is provided. The opening group is a liquid ejection head having at least one opening having an area different from the openings of other opening groups, and the total value of the opening groups having the largest total area of the openings among all the opening groups is , The total area value of the openings is 1.6 times or less of the total value of the smallest opening group, and the total area value of the openings forming the plurality of opening groups is the largest among the plurality of head portions. The total value of the head part is the surface of the opening. A liquid ejection head, wherein the total value of the products is 5 times or less of the total value of the minimum head portion. 14. A branch supply path, one end side of which communicates with a liquid supply port to which a liquid is supplied, and which branches from the middle to form a plurality of branch paths, and a plurality of communication paths which respectively communicate with the plurality of branch paths of the branch supply path. Of the common liquid chamber, a first head portion having a plurality of opening groups respectively communicating with these common liquid chambers via liquid paths, and each opening to the atmosphere, and a liquid supply port to which the liquid is supplied. And a second head portion having a common liquid chamber that communicates with the common liquid chambers via liquid paths and that has an opening group that respectively opens to the atmosphere, at least among all the opening groups. One opening group is a liquid ejection head having at least one opening having an area different from the openings of other opening groups, and the total of the area values of the openings among all the opening groups The value is the total area of openings The value is not more than 1.6 times the total value of the minimum opening group, and the total head area of the openings forming the opening group has the maximum total area of the first and second head sections. The total value is 5 times or less of the total value of the area of the openings of the minimum head portion, which is the liquid ejection head. 15. The liquid ejecting apparatus according to claim 13, wherein the number of openings of at least one opening group of all the opening groups is different from the number of openings of other opening groups. head. 16. The method according to claim 11, wherein the total value of the opening group having the maximum total area value of the openings and the total value of the opening group having the minimum total area value of the openings are substantially equal to each other. The liquid ejection head according to claim 15. 17. The print medium is arranged adjacent to a plurality of ejection openings arranged at a predetermined interval to eject a liquid onto a print medium, and the ejection openings located at an end portion in the arrangement direction. The liquid ejection head according to any one of claims 1 to 4 and 11 to 16, wherein the liquid ejection head has a liquid discharge port that is not involved in image formation with respect to the above. 18. The liquid ejection head according to claim 1, wherein the opening group is collectively covered with a common cap and suction is performed. 19. A liquid tank for storing a liquid can be connected to the liquid supply port, and the liquid tank has a porous body for holding the liquid. 18. The liquid ejection head according to any one of 18. 20. The liquid ejection head according to claim 1, further comprising an ejection energy generation unit provided in the liquid passage for ejecting a droplet from an opening. . 21. The liquid ejection head according to claim 20, wherein the ejection energy generation unit includes an electrothermal converter that generates thermal energy for causing film boiling in the liquid. 22. A liquid is ejected from the opening group of the liquid ejection head according to any one of claims 1 to 21 in a batch, so that the ejection state of liquid droplets from the opening group is maintained in a good state. And a suction recovery method for a liquid ejection head, wherein the amount of liquid sucked from each opening group is made substantially equal. 23. A liquid ejection head according to any one of claims 1 to 21, and a liquid tank for storing a liquid supplied to the liquid ejection head via a liquid supply port of the liquid ejection head. A head cartridge, which is characterized by including. 24. The liquid tank is attachable to and detachable from the liquid ejection head.
The head cartridge described in. 25. A plurality of ejection port groups of the liquid ejection head according to any one of claims 1 to 21, or a plurality of liquid ejection heads of a head cartridge according to claim 23 or 24. An image forming apparatus for forming an image on a print medium by a liquid discharged from a group of discharge ports, the mounting portion of the liquid discharge head or the head cartridge, a print medium conveying unit, and a plurality of the liquid discharge heads. A cap member capable of covering the ejection port surface where the ejection port group opens, and a suction recovery unit capable of sucking the liquid existing in the liquid ejection head from the plurality of ejection port groups via the cap member. An image forming apparatus comprising: 26. The image forming apparatus according to claim 25, wherein the mounting portion includes a carriage that can scan and move in a direction intersecting a print medium transport direction. 27. The image forming apparatus according to claim 26, wherein the liquid ejection head is removably mounted on the carriage via a detaching unit. 28. The method according to claim 25, wherein the liquid is a treatment liquid for adjusting the printability of the ink and / or the print medium.
The image forming apparatus according to any one of 1.