JPH0858075A - Inkjet head and inkjet printing apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] In an inkjet head having a structure for ejecting dark and light inks in one head, good printing is performed by effectively using the dark and light inks. [Structure] A discharge port 2K for discharging dark ink, a liquid passage 3 and a common liquid chamber 5K for storing ink to be supplied thereto, and a similar discharge port 2U for discharging light ink, a liquid passage 3 and a common liquid chamber 5U. In the ink jet head integrally formed with, the cross-sectional area of the discharge port 2U of the light ink is made larger than that of the discharge port 2K of the dark ink, and similarly, the common liquid chamber 5
U and the liquid chamber buffer 51U each have a common liquid chamber 5
The volume of each of K and the liquid chamber buffer 51K is made larger. As a result, it is possible to increase the discharge amount of the light ink and perform printing with good image quality, and it is possible to prevent deterioration of the ink supply property due to the increase of the discharge amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printing apparatus for printing by ejecting ink droplets onto a print medium and an ink jet head used in the printing apparatus.

Here, "print" means plain paper, OH
It means that a fixed image or the like is obtained by ejecting ink onto a medium such as P paper or the like, such as cloth or a filter, and is also referred to as "recording" in the following description.

[0003]

2. Description of the Related Art In the conventionally known ink jet recording system, ink is ejected from a plurality of ink ejection openings formed in a recording head based on a recording data signal, and the ejected ink droplets are ejected onto a recording medium such as paper. The recording is performed by attaching them. This recording method is used, for example, in printers, facsimiles, copiers, and the like.

Among such recording methods, in order to eject ink, a heating element (electrothermal energy conversion element) is provided near the ejection port, and an electric signal is applied to the heating element to locally heat the ink. Generally, a method of generating bubbles and then ejecting ink from a discharge port by a change in pressure of the bubbles and a method of using an electromechanical conversion element such as a piezoelectric element are well known.

In this type of recording method, a dot density control method in which the number of recording dots per unit area is controlled by recording dots of a fixed size to express a halftone, or the size of recording dots is controlled to express a halftone. The halftone recording control is performed by the dot diameter control method.

Here, the latter dot diameter control method generally has a restriction such that complicated control is required for subtly changing the size of the recording dot, and therefore the former dot density control method is generally used. Has been.

Further, as the ink ejecting means, the former method using the electrothermal energy conversion element, which is easy to manufacture and can achieve high density and can realize high resolution, controls the pressure change amount. The dot density control method is used in most cases because the range of diameters that can be modulated by this is small.

Further, as the ink ejecting means, the former method using the electrothermal energy conversion element, which is easy to manufacture and can achieve high density and can realize high resolution, controls the pressure change amount. In most cases, the dot density control method is used because the range of diameters that can be modulated by this is small.

By the way, as one of the typical binarization methods for halftone expression used in this dot density control method, there is an ordered dither method. In this method, the number of gradations is the matrix size. There is a problem that is limited by. That is, it is necessary to increase the matrix size in order to increase the number of gradations, but if the matrix size is increased, one of the recorded images formed by one matrix will be used.
There is a problem that the pixels become large and the resolution is impaired.

Another typical binarization method is a conditional decision type dither method such as an error diffusion method. This is an independent decision type dither method in which the systematic dither method described above is binarized by using a threshold value unrelated to the input pixel, whereas the threshold value is changed in consideration of the peripheral pixels of the input pixel. Is the way. The conditional decision type dither method represented by this error diffusion method has good compatibility of gradation and resolution, and when the original image is a printed image, a moire pattern is extremely rare in the recorded image. There are advantages. However, on the other hand, there is a problem that the graininess is apt to stand out in the image name portion, and the image quality is evaluated poorly. This problem was particularly remarkable in a recording device having a low recording density.

Therefore, in order to make the above-mentioned graininess inconspicuous, the conventional ink jet recording apparatus is provided with two recording heads for respectively ejecting a light color ink and a dark color ink, and the main part to the halftone part of the image are changed. A recording method has been proposed in which recording dots are formed with light-colored ink and recording dots are formed with dark-colored ink from the halftone portion to the dark portion. By the multi-valued light and shade recording method using a plurality of dark and light inks having different densities for the same color, the gradation of the highlight portion is particularly improved even if only binary printing is performed and ternary printing is performed, and the granularity by dots is obtained. It is possible to reduce the feeling and improve the image quality. This is because the noise feeling of a single dot is eliminated by hitting a low density (light) ink to the highlight part.

However, the recording method using such dark and light inks requires two recording dots corresponding to each of the dark and light inks, and further Y (yellow), M (magenta), C (cyan), and Bk. In the case of full-color recording of four-color configuration such as (black), a dark and light head is required for each, so a total of eight recording heads must be incorporated in the recording apparatus, resulting in an increase in the apparatus size and maintenance complexity. Sometimes it caused problems.

Therefore, in recent years, in order to solve the above-mentioned problems, a recording head having a structure in which dark and light ink is ejected in one head has been proposed.

[0014]

When recording, it is necessary to eject a large amount of light ink on the recording paper in order to enhance the gradation of the highlight portion. One such method is
In the case of a head having a structure in which two types of light and dark ink are ejected in one head, the ejection amount of the light ink per ejection is not changed, and the ink is ejected continuously a plurality of times in a short time to form one pixel. There is a method of increasing the amount of ink. However, in this case, the complexity of the head drive circuit and the head structure itself is increased, and it requires a considerably high technology to build a structure for ejecting the dark and light ink in the same head, and the cost is increased. It was supposed to.

Therefore, if a method of increasing the discharge amount of the light ink at one time is adopted as another means for increasing the discharge amount of the light ink, a desired head can be obtained without largely changing the configuration of the entire recording head. It is possible. However, the problem here is that if the basic design of the recording head is designed to eject dark ink, and if the ejection amount is simply increased, the balance of the ink supply system to each ejection port of the head is disturbed and printing is performed. The problem is that it cannot be done properly.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet head having a structure for ejecting dark and light ink in one head, and the characteristics of each ink. Another object of the present invention is to provide a good inkjet head and an inkjet printing apparatus according to a print image design.

[0017]

Therefore, according to the present invention,
In an ink jet head for ejecting ink, a plurality of ejection ports for ejecting different kinds of ink and an energy acting unit for communicating with each of the plurality of ejection ports and for applying energy used for ink ejection And a plurality of liquid chambers communicating with the energy acting portion and storing ink supplied to the acting portion for each of the different types of ink, and an amount of ink ejected from the plurality of ejection ports by one ejection And a means for making each of the ejection ports corresponding to different types of ink different, and the volumes of the plurality of liquid chambers differ depending on the ejection ink amount of the ejection port corresponding to each type of ink. Is characterized by.

More preferably, the means is constituted by making the areas of at least the plurality of ejection ports different from each other.

Further, the different types of ink are different in type depending on the density, and the area of the ejection port is larger as the ejection port ejecting the ink of lower concentration.

In addition, each of the plurality of liquid chambers is provided with a bubble holding portion, and the volume of the bubble holding portion differs depending on the ink ejection amount of the corresponding ejection port depending on the type of ink. Characterize.

In addition, in an ink jet printing apparatus which uses an ink jet head for ejecting ink and ejects ink from the head onto a print medium to perform printing, the ink jet head includes a plurality of ink jet heads for ejecting different kinds of ink. An ejection port, and an energy acting unit that communicates with each of the plurality of ejection ports and applies energy used for ejecting ink,
A plurality of liquid chambers communicating with the energy acting portion and storing ink supplied to the energy acting portion for each of the different types of ink; and an amount of ink ejected from the plurality of ejection ports by one ejection, And a means for making different for each of the ejection openings corresponding to different types of ink, the volumes of the plurality of liquid chambers differ according to the ejection ink amount of the ejection openings corresponding to each type of ink. And

[0022]

According to the above construction, when the inks of different kinds such as dark and light inks are ejected by the integral construction, the ejection port area is increased to increase the ejection amount of the light ink and the image quality is improved. In such a case, the ink supply failure due to the refill characteristic that may occur due to the increase in the ejection amount is prevented in advance by the increase in the volume of the common liquid chamber relating to the light ink and further by the increase in the volume of the liquid chamber buffer. .

[0023]

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

(Embodiment 1) FIG. 1 is a perspective view showing a main configuration of a color ink jet printing apparatus according to an embodiment of the present invention.

In FIG. 1, an ink jet head (recording head) 12 has an ejection port array for ejecting dark color ink and an ejection port array for ejecting light color ink on the same head, as will be described later with reference to FIG. It is set up. The recording head 12 is detachably attached to the carriage 23, and is connected to the ink tank IT which is also attached on the carriage 23. The carriage 23 is slidably engaged with the guide shaft 22, and thereby, the carriage 23 can be reciprocated along the guide shaft 22 by the drive of the carriage motor 25 via the drive belt 24.

Inside the ink ejection port (liquid path) of the recording head 12, a heating element (electrical heat energy conversion element) for generating thermal energy used for ejection is provided.

A recording medium P such as a recording sheet is inserted from the front side of the apparatus as indicated by an arrow in the drawing, conveyed by a conveying roller (not shown), passes over the platen 27, and is ejected to the outside of the apparatus by a sheet ejection roller 21. . During this conveyance, ink is ejected from the recording head 12 onto the recording medium P whose recording surface is made flat by the platen 27. That is, in accordance with the reading timing of the encoder (not shown), the heating element of the print head is driven based on the print signal to drive dark ink,
An image can be formed by ejecting and adhering ink droplets on the recording medium P in the order of light ink.

At the home position HP of the carriage located outside the recording area, a recovery unit having a cap portion 26 is arranged. At the time of non-recording, the carriage 23 is moved to the home position HP and the cap portion 2 is moved.
The cap 6 covers the ink ejection port forming surface of the corresponding recording head 12 to prevent clogging of ink due to evaporation of the ink solvent or clogging due to adhesion of foreign matter such as dust and dust. Further, the capping function of the cap portion 26 is set to a preliminary ejection mode in which ink is ejected to the cap portion 26 which is away from the ink ejection port in order to eliminate ejection failure and clogging of the ink ejection port with low recording frequency. It is used to prevent the ejection recovery of the ink ejection port that caused ejection failure and such ejection failure by operating a pump (not shown) in the cap state to suck ink from the ink ejection port. . Also, by arranging the blade and blowing member at the position adjacent to the cap part,
It is possible to clean the surface of the inkjet head on which the ink ejection ports are formed.

FIG. 2 is a schematic perspective view of the recording head 12 as seen from the ink ejection port array side, and FIG. 3 is a perspective view schematically showing the structure of the ink ejection portion of the recording head 12.

As shown in these figures, a plurality of ejection ports are provided on the ejection port formation surface 1 of the recording head. That is,
A plurality of ejection ports 2K for ejecting dark ink and a plurality of ejection ports 2U for ejecting light ink are provided. A liquid path 3 having the opening end as an opening end is connected to each of the ejection ports, and heating elements 4 for generating thermal energy used to eject ink are arranged in the liquid path 3. The arrows in these figures indicate the scanning direction of the carriage.

Each of the liquid passages 3 communicates with a common ink chamber 5 at the end opposite to the ejection port 2k (2u). As described above, the recording head 12 is divided into a dark ink ejecting portion and a light ink ejecting portion in one head, and thus this common ink liquid chamber has a structure in which ink having different densities is partitioned. . Each common ink liquid chamber has an ink supply path 2200.
Is connected to the ink tank IT.

FIG. 4 is a perspective view schematically showing the details of the main part of the recording head of the above-mentioned embodiment.

In FIG. 4, the structure in which the K portion is on the dark ink side and the U portion is on the light ink side is shown with the surface surrounded by the alternate long and short dash line in the central portion as a boundary. Generally, when the same head is used for the composition of each of the dark ink and the light ink, the solvent components are almost the same, and the coloring material changes depending on the density. In the case of the present embodiment, in the black ink, a dye is used as a coloring agent in a solvent of glycerin, thiodiglycol, and urea of 5% by weight and isopropyl alcohol of 4% by weight, respectively.
The dark ink was 3% by weight, the light ink was 1% by weight, and the rest was water.

In the case of other colors, the ratio of dyes is slightly different, but the ratio of dark and light is preferably 3: 1.

Here, in the multi-valued dark and light ink jet printing, as described above, since a large amount of the light ink is used to enhance the gradation of the highlight portion, the ink ejection amount of the light ink is higher than that of the dark ink. Need to increase by about 70%.

Therefore, in the present embodiment, a method of increasing the ink ejection amount is achieved by changing the area of the ink ejection port depending on the density. In the case of a black ink head, the dark ink ejection port 2k is 400 μm ² and an ink ejection amount of about 30 ng is obtained, while the light ink ejection port 2u is 600 μm.
^By setting to ² , it became possible to obtain a discharge amount of about 50 ng. Along with this, 5U of light ink common liquid chamber
The volume of the dark ink common liquid chamber 5k is increased.

However, when the ejection port area is increased to increase the ink ejection amount, the balance of the ink supply system is disturbed, and when ejecting continuously from the same ejection port, it is formed on the recording paper by the ejection following the first ejection. The formed dots may not be formed well and the recording quality may deteriorate.

This is because the so-called refill characteristic changes due to the increase in the ejection opening area. That is, if the supply characteristic from the common ink chamber to the flow path is lowered due to the change of the refill characteristic, the refill time becomes long, and therefore the ink is sufficiently refilled during the second ejection after the first ejection. This is because the ink droplets are not formed properly because they are ejected before they are ejected.

By the way, as a means for solving this problem, a so-called liquid chamber buffer where ink does not enter (is difficult to enter) is provided in the common ink chamber to prevent the refill time before the second ejection from becoming long. It has been known. It is presumed that this principle is because the gas in the liquid chamber buffer expands and contracts in accordance with the operation of the ink due to the bubbling energy, thereby absorbing the bubbling energy that acts on the common ink chamber side during ejection.

Therefore, in this example, the configuration of the liquid chamber buffer 51 is changed between the dark ink side and the light ink side in response to the change in the refill characteristic. That is, since the light ink is about 70% larger than the discharge amount of the dark ink, the buffer volume and the common ink chamber volume that match the light ink are required, and the volume of the dark ink liquid chamber buffer 51k is 0.05 to.
To 0.1 mm ^3, the light ink side liquid chamber buffer 51u
The preferable range of the volume is 0.1 to 0.2 μm ³ .

In this example, the buffer volume for the case of 64 light and dark discharge ports is determined as described above, but the volume that matches the basic characteristics of the head, such as the discharge port, discharge volume, and response frequency, is the same. Of course, it is decided each time.

(Embodiment 2) FIG. 5 is a perspective view showing a main structure of an ink jet printing apparatus for performing full color printing according to another embodiment of the present invention, and recording heads 12Bk, 12C corresponding to individual ink colors. , 12M, 12Y
And ink tanks ITBkk, u, ITCk, u, I
Other than TMk, u, TYk, u, the basic configuration is the same as that of the above-described first embodiment, and therefore its description is omitted.

FIG. 6 is a schematic perspective view of a part of the recording head of this embodiment as seen from the ink ejection port array side.

As shown in the figure, each of the four-color recording heads of C (cyan), M (magenta), Y (yellow), and Bk (black) has an ejection port array for ejecting a dark color ink and a light color ink. And a discharge port array for discharging, and is mounted on the carriage at a predetermined distance.

When recording is performed using dark and light inks, the deviation of the landing positions of the dark ink dots and the light ink dots is also very important, and the density may change due to the deviation of the dots. As in the present embodiment, by dividing the ink having different densities of light and dark in one recording head, there is no shift in the vertical and horizontal resists, and there is no possibility that density gradation shift due to the landing position will occur. ing.

FIG. 7 is an exploded perspective view showing the structure of the ink jet head used in this embodiment.

One end of the wiring board 200 is connected to the heater board 1
00 wiring part, and the wiring board 20
The other end of 0 is provided with a plurality of pads corresponding to the respective electrothermal energy conversion elements (heat generating elements) for receiving an electric signal from the apparatus body. As a result, the electric signal from the device body is selectively supplied to each electrothermal energy conversion element.

The metal support 300 that supports the back surface of the wiring board 200 on a plane serves as a bottom plate of the ink jet unit. The pressing spring 500 includes a portion formed by bending a region near the ink ejection port of the grooved top plate 1300 in a linear shape elastically and pressing force to act on the region, and an escape hole formed in the base plate. And a pair of rear legs for receiving the force acting on the spring by the base plate. The wiring board 200 and the grooved top plate 1300 can be pressed against each other by the pressing force.

The wiring board 200 is attached to the support by sticking with an adhesive or the like. Ink supply pipe 22
A filter 700 is provided at the end of 00. The ink supply member 600 including the supply pipe 2200 is formed by molding, and the grooved top plate 1300 also integrally has the orifice plate portion 1301 and the flow passage 1500 leading to each ink supply port. Has been formed. To fix the ink supply member 600 to the support 300, two pins (not shown) on the back surface side of the ink supply member 600 are projected through the holes 1901 and 1902 of the support 300, respectively, and heat-sealed. Done by. At this time, the gap between the orifice plate portion 1301 and the ink supply member 600 is formed uniformly. The hooking agent is injected from the top hooking agent injection port of the ink supply member 600 to seal the wire bonding and at the same time to the orifice plate portion 13.
01 and the ink supply member 600 are locked, and further, the gap between the orifice plate portion 1301 and the front end of the support base 300 is locked by passing through the groove 310 provided in the support base 300.

FIG. 8 is a perspective view of the grooved top plate 1300 of the recording head shown in FIG. 7 as viewed from the heater board 100 side.

Two common liquid chambers are provided for each of the dark and light inks.
The individual liquid chambers 5k and 5u are partitioned by the wall 10, and the light ink liquid chamber 5u has a larger volume than the dark ink liquid chamber 5k. Supply ports 20k and 20u for supplying ink are provided in each liquid chamber. In addition, liquid chamber buffers 51k and 51u are provided on both sides of each liquid chamber.
Respectively, and the dark ink liquid chamber buffer 51
The volume of the light ink liquid chamber buffer 51u is larger than k.

Grooves 30 are provided on the pressure contact surface of the wall 10 for partitioning each liquid chamber with the heater board 100. This groove communicates with the outer peripheral portion of the grooved top plate 1300. Groove top plate 13
After pressing 00 to the heater board to bring them into close contact,
As described above, it is sealed with the latch. At this time, the latching agent penetrates along the groove to fill the gap between the grooved top plate and the heater board. In this way, the liquid chamber can be completely separated by the technical process conventionally used in the head. The structure of this groove differs depending on the physical properties of the sealant, and it is necessary to make the shape corresponding to each. in this way,
By separating the liquid chamber into a plurality of chambers, different inks can be supplied to the respective ink ejection ports.

FIG. 9 shows 4 of C, M, Y and Bk of this embodiment.
FIG. 3 is an exploded perspective view showing the structure of a 4-head integrated ink jet cartridge in which color recording heads are integrally assembled with a frame 3000.

The four recording heads are mounted in the frame 3000 at predetermined intervals and are fixed in a state where the resist in the ejection port array direction is adjusted. Reference numeral 3100 is a frame cover, and 3200 is a connector for connecting pads provided on the wiring board 200 of the four recording heads and electrical signals from the main body apparatus.

FIG. 10 is a perspective view showing a state in which the four-head integrated ink jet cartridge and the ink tank shown in FIG. 9 are mounted on the carriage.

Ink tanks ITBk, C, for each ink
M and Y are divided into upper and lower rooms, and the upper room is filled with dark ink and the lower room is filled with light ink. Then, the above-mentioned ink jet cartridge and the four ink tanks C, M, Y and Bk are pressure-bonded on the carriage to supply each ink from the ink tank to the recording head.

Also in this embodiment, the structure is such that the ejection port area, the common ink chamber volume, and the liquid chamber buffer volume as the bubble holding portion are changed between the dark and light inks.

In this embodiment, the color ink jet recording apparatus with four colors of cyan, magenta, yellow and black has been described, but the number of colors is not particularly limited to this and as described in the first embodiment. Even in monochrome monochrome,
It can also be applied to a color recording apparatus having a plurality of different dark and light inks.

Further, the dye concentration of the ink is not limited to two kinds of light and shade, but may be three or more kinds. This is because if there is a large difference in dot density between the dark and light inks of color, the gradation reproduction is not linear at the switching portion of the light ink and the dark ink, and pseudo contours are likely to occur. This can be properly prevented.

Further, a change in graininess or a change in color tone of the recorded image may occur at the ink switching portion, resulting in an unnatural image. In such a case, low density ink and medium density ink A more preferable print image can be obtained by increasing the number of ink colors and recording by using high-density ink.

[0061]

As described above, according to the present invention, when the inks of different types such as dark and light inks are ejected by the integrated structure, the ejection port area is increased to reduce the amount of the light ink. When the ejection amount is increased to improve the image quality, the ink supply failure due to the refill characteristic that may be caused by the increase in the ejection amount is caused by the increase in the volume of the common liquid chamber related to the light ink and further by the liquid chamber buffer. It is prevented by the volume increase.

As a result, it is possible to obtain a high quality ink jet head having high gradation reproducibility under the same driving condition.
Furthermore, it becomes possible to provide a low-priced and small-sized inkjet printing apparatus using this head.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing an outline of a recording head used in the above apparatus.

FIG. 3 is a perspective view schematically showing a structure of an ink ejection portion of the recording head.

FIG. 4 is a perspective view schematically showing details of a main part of a recording head according to an embodiment of the present invention.

FIG. 5 is a perspective view showing an outline of a color inkjet printing apparatus according to another embodiment of the present invention.

FIG. 6 is a schematic perspective view of the recording head in the above apparatus as viewed from the ejection port array side.

FIG. 7 is an exploded perspective view showing the configuration of the recording head shown in FIG.

FIG. 8 is a perspective view illustrating a grooved top plate of the recording head.

9 is an exploded perspective view illustrating the configuration of the inkjet cartridge with four heads shown in FIG.

FIG. 10 is a perspective view for explaining a carriage mounting state of the inkjet cartridge with four heads integrated therein.

[Explanation of symbols] 2k dark ink ejection port 2u light ink ejection port 3 liquid path 4 heating element (electrothermal conversion element) 5, 5k, 5u common liquid chamber 12Bk, 12C, 12M, 12Y recording head 51k dark ink liquid chamber buffer 51u Light ink liquid chamber buffer ITBk, ITC, ITM, TY ink tank

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location B41J 2/05 B41J 3/04 102 Z 103 B (72) Inventor Masami Ikeda 3 Shimomaruko Ota-ku, Tokyo Chome 30-2 Canon Inc.

Claims (5)

[Claims] 1. In an ink jet head for ejecting ink, a plurality of ejection ports for ejecting different kinds of ink and the plurality of ejection ports are respectively communicated with each other, and energy used for ejecting ink is applied. And a plurality of liquid chambers that communicate with the energy acting unit and store the ink supplied to the acting unit for each of the different types of ink, and a single ejection from the plurality of ejection ports. Means for varying the ejected ink amount for each ejection port corresponding to a different type of ink, and the volume of the plurality of liquid chambers is the ejection ink amount of the ejection port corresponding to each type of ink. An inkjet head that is different according to. 2. The ink jet head according to claim 1, wherein the means is configured by making at least respective areas of the plurality of ejection openings different from each other. 3. The different types of ink are different in type depending on the density, and the area of the ejection port is larger as the ejection port ejecting the ink of lower concentration. The described inkjet head. 4. A plurality of liquid chambers are provided with bubble holding portions, respectively, and the volume of the bubble holding portions varies depending on the ink ejection amount of a corresponding ejection port depending on the type of ink. The inkjet head according to any one of claims 1 to 3. 5. An inkjet printing apparatus for performing printing by using an inkjet head for ejecting ink and ejecting the ink from the head onto a print medium, wherein the inkjet head comprises a plurality of inkjet heads for ejecting different kinds of ink. An ink acting on each of the ejection ports and each of the plurality of ejection ports, which acts on the energy used for ejecting the ink, and an ink acting on the energy action part. A plurality of liquid chambers that store the different types of ink, and a means that makes the amount of ink ejected from the plurality of ejection ports in one ejection different for each ejection port corresponding to a different type of ink, The volume of the plurality of liquid chambers is the amount of the ejected ink at the ejection port corresponding to the type of ink. An inkjet printing apparatus, which is different according to the type.