JPH1029307A - Ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink jet recorder performing high density printing. SOLUTION: In an ink jet recorder performing high density printing at 480dpi or above, an ink jet port 13 has a size of ϕ40μm or less and the surface of a part 3 for imparting energy to an ink 15 is set substantially in parallel with the ink jet port 13. According to the structure, a jet energy imparted to the ink 15 from the energy imparting part 3 can be used efficiently for jetting the ink 15. Furthermore, since the ink is jetted from the ink jet port 13 at a rate of 10m/s or above even if the aperture of the ink jet port 13 is decreased for the purpose of high density printing, the ink can be jetted well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for performing printing by discharging ink, and more particularly to an ink jet recording apparatus capable of performing printing at a density higher than 400 dpi (dot par inch).

[0002]

2. Description of the Related Art The non-impact recording method has been attracting attention for office use and the like because the noise generation during recording is extremely small to a negligible level. inside that,
The so-called ink jet recording method is an extremely effective recording method that can perform high-speed recording and can perform recording without requiring a special fixing process on plain paper.
Various systems have been proposed or commercialized and put into practical use.

In such an ink-jet recording method, recording is performed by flying small droplets (ink droplets) of a recording liquid called so-called ink and attaching the ink droplets to a recording medium. For example, the applicant filed Japanese Patent Publication No. 56-9
No. 429. Here, the invention described in JP-B-56-9429 can be summarized as follows:
By heating the ink in the liquid chamber to generate bubbles, a pressure rise is generated in the ink, and the ink is ejected from an ink ejection port at the tip of a fine nozzle to perform recording.

After that, many inventions have been made utilizing this principle. One of them is, for example, Japanese Patent Publication No. 62-5967.
The invention described in Japanese Patent Publication No. 2 is known. This is achieved by installing an energy acting part such as a heating element or a piezoelectric element as an energy source for discharging ink on a substrate obtained by forming ceramics such as alumina, metal, plastics, etc. After forming a conductive resin layer by a coating method or a laminating method, an ink flow channel is formed on the photosensitive resin layer by a photolithography method usually performed, and then a substrate provided with the ink flow channel is provided. To form an ink jet recording head. Also, Japanese Patent Application Laid-Open No. Sho 57-4
The invention described in Japanese Patent No. 3876 is known,
This is one step further from the invention described in Japanese Patent Publication No. 62-59672 described above. After joining the upper cover, the ink discharge port is formed by cutting the substrate and the upper cover by a dicing method. As mentioned, the method of manufacturing the ink jet recording head is more clear.

However, in the above publication,
Although there is a description of a method for forming a configuration (ink flow channel groove, ink ejection port, etc.) necessary for an ink jet recording head on a substrate by using a technique such as photolithography, the specific size of the ink jet is described. There is no mention of whether to make a recording head.

On the other hand, Japanese Patent Application Laid-Open No. 55-132267 discloses that, as described in the specification,
An ink jet recording head in which ink ejection ports are arranged at a density of about 200 mm (200 to 300 pieces / inch) has been studied. In Japanese Patent Application Laid-Open No. 55-161665, the size of a heating resistor pattern (energy acting portion) is 80 μm × 200 μm, as described in the specification.
Since the size of the ink flow passage groove forming the ink discharge port at the tip is 80 μm in width × 80 μm in depth, an ink jet recording head having an ink discharge port array density of about 8 / mm is being studied. .

[0007]

However, in recent years,
There is a demand for higher definition and higher image quality recording quality, and it is no longer possible to meet the needs of the market with an ink jet recording head having an ink ejection port arrangement density as disclosed in the above-mentioned prior art. Specifically, 400 dpi
The above-mentioned high-density recording has been demanded, and the conventional ink jet recording head cannot cope with this.

An ink jet recording head capable of performing such high-density recording has not been realized, and therefore, it has not been sufficiently studied that a specific method for performing high-density recording of 400 dpi or more has been sufficiently studied. It is.

Therefore, the present invention provides a printing density of 400 dpi.
An object of the present invention is to provide an ink jet recording apparatus capable of achieving the above high density printing.

[0010]

According to the first aspect of the present invention,
In an ink jet recording apparatus that performs high-density printing of 480 dpi or more, the size of the ink ejection port is set to φ40 μm or less, and the surface of an energy applying section that applies ejection energy to ink is substantially parallel to the ink ejection port. Therefore, by making the surface of the energy application section that applies the ejection energy to the ink substantially parallel to the ink ejection port, the ejection energy given to the ink from the energy application section is efficiently used for ejecting the ink. For this reason, even with an ink jet recording apparatus that performs unprecedented high-density printing by reducing the size of the ink ejection port, the ink ejected from the ink ejection port can achieve an ejection speed of 10 m / s or more, and Dispenses stably at high speed.

According to a second aspect of the present invention, in the ink jet recording apparatus according to the first aspect of the present invention, the energy application section is a heating element that applies thermal energy to the ink from its surface to generate bubbles in the ink. The ink is ejected in a direction substantially perpendicular to the surface of the energy application section by the action force of the bubble. Accordingly, since the action force of the bubbles generated in the ink is used for the ink ejection without waste, the ink ejected from the ink ejection port is 10 m even in an ink jet recording apparatus which performs a high-density printing which has not been conventionally performed. / S or more is obtained, and the ink is stably ejected at a high speed.

According to a third aspect of the present invention, in the ink jet recording apparatus of the second aspect, the heating element has a size of 45 μm × 45 μm or less. Therefore, since the acting force of the bubbles generated in the ink is used for the ink ejection without waste, the ink ejection can be favorably performed even if the heating element is downsized.

According to a fourth aspect of the present invention, in the ink jet recording apparatus according to the first, second or third aspect of the present invention, the ink discharge ports are perforated by excimer laser processing on a resin sheet, and the ink discharge ports are perforated. The thickness of the resin sheet was 10 μm to 50 μm. Therefore, when drilling the ink ejection port by excimer laser processing,
Since the thickness of the resin sheet at the portion of the resin sheet where the ink ejection ports are perforated is 10 μm to 50 μm, the dimensional accuracy of the ink ejection ports is increased.

According to a fifth aspect of the present invention, there is provided an ink jet recording apparatus comprising an ink jet recording head having an ink discharge port for discharging ink and an energy action section for applying ejection energy to the ink, wherein the ink jet recording head faces the energy action section. Forming the ink ejection port on the side,
The ink is ejected in a direction substantially perpendicular to the energy application section to perform printing, and the printing density is 400%.
The ink jet recording head of dpi to 800 dpi is:
The distance from the surface of the energy application section to the outer surface of the ink ejection port was set to 40 μm to 70 μm. Therefore, by setting the distance from the surface of the energy application section to the outer surface of the ink ejection port to be 40 μm to 70 μm,
The ink to be ejected is not scattered, and 10m / s
The above ejection speed can be obtained, and the ink is ejected stably at high speed.

[0015]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a completed view of an ink jet recording head 1 used in an ink jet recording apparatus according to the present invention, and FIG. 2 is an exploded perspective view thereof. First, a plurality of heating elements 3 serving as energy action sections are provided in a row on a heating element substrate 2 serving as a substrate. Further, these heating elements 3 are provided with individual control electrodes 4 and a common electrode 5. Are electrically connected. The ends of these electrodes 4 and 5 are led out to the same side of the heating element substrate 2 and are used as bonding pads 6 and 7, respectively. An ink introduction port 8 for introducing ink is formed through the heating element substrate 2 at an end of the heating element 3 in the arrangement direction, and ink is introduced through the ink introduction port 8 through a filter 9. Tube 10 is connected. The heating element substrate 2
A lid member 12 having a concave portion 11 large enough to cover the heating element 3 and the ink inlet 8 is laminated on the upper portion. The lid member 12 is laminated so that the concave portion 11 faces the heating element 3, and a portion surrounded by the upper surface of the heating element substrate 2 and the concave portion 11 is an ink into which ink is introduced. Room. In addition, an ink discharge port 13 is formed in the cover member 12 at a position facing the heating element 3. FIG. 3 is a perspective view of the lid member 12 as viewed from the inside, and a barrier, which is a convex portion protruding toward the heating element 3, is provided around the ink discharge port 13 on the inner peripheral surface of the lid member 12 on the concave portion 11 side. 14 are formed.

Note that FIGS. 1 to 3 and FIGS.
In each of the drawings described later, for simplification of the description, a simplified structure or the like is illustrated as necessary, and has some omissions and exaggeration points. For example, the heating element substrate 2 is provided with a heat storage layer, a protective layer, and the like in addition to the heating element 3 and the electrodes 4 and 5, but is not illustrated here and will be described later. Although the number of pairs of the heating element 3 and the ink discharge port 13 is only three in the illustrated example, a large number is actually provided, and in the example of the low-end serial printer, 64 pairs are provided.
Up to 256 printers are provided, and in an example of a high-end multi-printer, 2000 to 4000 printers are provided. Further, as the number of heating elements 3 and the like increases, the number of ink introduction ports 8 increases, or the opening area increases. In the case of the heating element substrate 2 made of, for example, silicon, the ink inlet 8 can be easily formed by laser beam processing or etching. Further, the dimensional ratios of the respective parts in the illustrated example are given priority for ease of understanding, and are not necessarily realistic.

Next, the principle of discharging the ink 15 will be described with reference to FIG. FIG. 4 is a cross-sectional view of the vicinity of the ink ejection port 13 in the ink jet recording head 1.

First, FIG. 1A shows a steady state, in which the surface tension of the ink 15 and the external pressure at the ink discharge port 13 are kept in an equilibrium state.

FIG. 2B shows that the heating element 3 is heated, the surface temperature of the heating element 3 rises rapidly, a film boiling phenomenon occurs in the adjacent ink layer, and a boiling film is formed, and bubbles 16 are formed on the surface of the heating element 3. It has grown. At this time, the pressure of the ink ejection port 13 rises by the growth of the bubble 16, the balance with the external pressure is lost, and the ink column 15 a starts to grow from the ink ejection port 13.

FIG. 3C shows a state in which the bubble 16 has grown to the maximum, and the ink column 15 a is pushed out from the ink discharge port 13. At this time, no current is flowing through the heating element 3, and the surface temperature of the heating element 3 is decreasing. The maximum value of the volume of the bubble 16 is slightly delayed from the timing of applying the electric pulse to the heating element 3.

FIG. 2D shows a state in which the bubble 16 has been cooled and contracted by the ink 15 or the like. At the front end of the ink column 15a, the ink column 15a advances while maintaining the pushed speed, and at the rear end, the ink 15 flows backward due to a decrease in the pressure in the ink discharge port 13 due to the contraction of the bubble 16, and the root of the ink column 15a After constriction, the ink column 15a is cut from the constricted portion, and is discharged from the ink discharge port 13 as an ink droplet 15b. At this time, since the internal pressure of the ink ejection port 13 is lower than the external pressure, the meniscus is large and the ink ejection port 13
It will be in a state of getting inside. The tip of the ink droplet 15b at the time of ejection has an ejection speed of 10 to 18 m / s, and ejects toward a recording paper (not shown) provided at a position facing the ink ejection port 13.

FIG. 5E shows the ink 1 due to the capillary phenomenon.
5 is again supplied to the ink ejection port 13 and returned to the same state as shown in FIG. 9A, and the bubble 16 has completely disappeared.

Hereinafter, the configuration and manufacturing method of each part for improving the above-mentioned ejection principle will be individually described. First, the structure of the heating element substrate 2 and its manufacturing method will be described with reference to FIG. The heating element substrate 2 is one of important parts in the present embodiment, and the heating element substrate 2 itself is made of a material such as glass, alumina (Al ₂ O ₃ ), or silicon. The heat storage layer 17 formed on the heating element substrate 2 is made of, for example, an SiO ₂ layer. In the case of a glass or alumina substrate, it is formed by a thin film forming method such as a sputtering method. Formed by the method. The thickness of the heat storage layer 17 is preferably about 1 to 5 μm.

The material constituting the heating element 3 is a mixture of tantalum-SiO ₂ , tantalum nitride, nichrome, silver
A palladium alloy, a silicon semiconductor, or a boride of a metal such as hafnium, lanthanum, zirconium, titanium, tantalum, tungsten, molybdenum, niobium, chromium, and vanadium can be used. Of these, metal borides are particularly preferable, and among them, hafnium boride is most preferable, and then zirconium boride, lanthanum boride, vanadium boride, and niobium boride are preferable in this order. The heating element 3 is formed using such a material by an electron beam method, an evaporation method, a sputtering method, or the like. The film thickness is appropriately set according to the area, the material, the shape and size of the heat acting portion, the power consumption on the actual surface, and the like so that the calorific value per unit time becomes a desired value. 0.001 to 5 μm, preferably 0.01 to 1 μm
Degree.

As a material of the control electrode 4 and the common electrode 5,
It may be the same as a normal electrode material, for example, Al, Ag, A
u, Pt, Cu and the like are used. These are formed at a predetermined position in a predetermined size, shape, and film thickness by an evaporation method or the like. A protective layer 18 is formed on the heating element 3, and the protective layer 18 protects the heating element 3 without preventing heat generated by the heating element 3 from being effectively transmitted to the ink 15 side. As a material, silicon oxide (SiO ₂ ), silicon nitride, magnesium oxide, aluminum oxide, tantalum oxide, zirconium oxide, or the like is used. The production method is based on an electron beam method, an evaporation method, a sputtering method, or the like. The film thickness is usually 0.01 to 10 μm, preferably 0.1 to 5 μm (among others, 0.1 to 3 μm is optimal). The protective layer 18 is formed of one or more layers using these materials. In addition to these layers, the protective layer 18 is made of tantalum or the like to protect against cavitation generated when the air bubbles 16 contract and disappear. It is desirable to form a metal layer on the surface. Specifically, a metal layer such as tantalum may be formed with a thickness of about 0.05 to 1 μm.

An electrode protection layer 19 is formed on the electrodes 4 and 5.
Are formed. Examples of the material of the electrode protective layer 19 include polyimide isoindoloquinazolinedione (trade name: PIQ, manufactured by Hitachi Chemical Co., Ltd.), polyimide resin (trade name: PYRALIN, manufactured by DuPont), cyclization Polybutadiene (trade name: JSR-CBR, manufactured by Nippon Synthetic Rubber Co., Ltd.), Photo Nice (trade name, manufactured by Toray Industries, Inc.), and other photosensitive polyimide resins are used.

Next, the lid member (see FIGS. 1 to 3)
Twelve manufacturing methods will be described. The lid member 12 is formed by integral molding of a resin, and as a resin material, polysulfone, polyethersulfone, polyphenylene oxide, polypropylene, or the like having excellent ink resistance is used. Among them, good fluidity for molding (melt flo
It is preferable to use a material having a w rate of 10 g / 10 min or more). As the molding machine, a commercially available injection molding machine is used, but the injection pressure is set to 2000 kg /
A molding machine having a capacity of at least cm ² is desirable. Further, in order to increase the fluidity of the resin, the cylinder temperature is heated to 400 ° C. or higher. As the mold, a mold having a shape to be paired with the lid member 12 shown in FIG. 3 is used. Also, to improve the transferability,
A heater, a thermal catalyst, and the like are provided in the mold so that the material can be heated to a temperature higher than the heat deformation temperature of the material of the mold. It is also effective to increase the transferability by reducing the pressure of the resin-filled portion of the mold using a vacuum pump or the like.

In the above description, the lid member 12 and the ink discharge port 13 are integrally formed at the same time. However, as another method, a resin sheet having no ink discharge port 13 in a mold is formed. Then, the resin sheet taken out of the mold is irradiated with ultraviolet light by a laser device to remove and evaporate the resin, thereby forming the ink ejection port 13.
The highly accurate ink ejection port 13 can be formed. In particular, when an excimer laser is appropriately used, precise processing along the mask pattern can be easily performed. For example, as in the case of the ink jet recording head 1 that performs extremely high-density printing exceeding 400 dpi, for example. ,
It is very convenient to form an ink ejection port 13 that is small (smaller than φ30 μm) than ever before.

The above is a brief description of the ink jet recording head 1 used in the ink jet recording apparatus of the present invention. As apparent from FIG. A side shooter method for discharging the droplet 15b is employed. On the other hand, as shown in FIG. 6, there is an ink jet recording head of a system (edge shooter system) in which an ink droplet 15b is discharged in a direction parallel to the surface of the heating element 3. The present applicant has made various types of ink jet recording heads of both structures and measured them. As a result, in order to perform very high-definition printing, for example, high-density printing exceeding 400 dpi, a side shooter method was used. Was found to be suitable. Tables 1 and 2 show the measurement results. Table 1 shows a prototype of an ink jet recording head of the edge shooter type, in which ink droplets 15b are ejected, and the ejection speed of the tip of the ejected ink droplets 15b is measured. This is the result. On the other hand, Table 2 shows the results of similar measurements made on a trial production of a side shooter type ink jet recording head. Here, the prototype ink jet recording head has 64 ink ejection ports, and its array density is changed from 300 to 1000 / inch.
The used ink 15 has a surface tension of 40.5 dyn.
/ Cm and a viscosity of 1.62 cp. Further, in the side shooter type ink jet recording head, four barriers 14 as shown in FIG. 3 were formed around the ink discharge ports 13 as shown in FIG. In addition, the driving frequencies were all unified to 5 kHz.

[0030]

[Table 1]

[0031]

[Table 2]

As is clear from the above measurement results, in the edge shooter type ink jet recording head, when the arrangement density of the ink discharge ports is 480 / inch or more,
The ejection speed at the tip of the ink droplet became 10 m / s or less.

On the other hand, in the ink jet recording head of the side shooter system, even if the arrangement density of the ink ejection ports exceeds 480 / inch, the ejection speed of the tip of the ink droplet was 13 m / s or more.

As described above, it is considered that the difference in the ejection speed of the leading end portion of the ink droplet occurs between the edge shooter type and the side shooter type ink jet recording head due to the structure. In the side shooter type inkjet recording head 1 applied to the present invention,
Since the ink ejection port 13 is located right above the generated bubble 16, the growth direction of the bubble 16 matches the ejection direction of the ink droplet 15 b. Therefore, the driving force of the ink ejection due to the growth of the bubbles 16 is transmitted to the ink 15 very efficiently,
The ratio (discharge efficiency) of the discharge energy directly used for discharging the ink 15 to the discharge energy given to the ink 15 from the heating element 3 increases. Further, in the present embodiment, since the barrier 14 is provided around the ink discharge port 13, the propulsive force is hardly dispersed in the lateral direction, and the discharge efficiency is further improved.

On the other hand, FIG. 7 shows the growth direction of the generated bubbles 16 and the ejection direction of the ink 15 in the ink jet recording head of the edge shooter system. At 90 °, they do not coincide with each other, and half of the propulsive force of ink discharge escapes in the opposite direction (the direction of arrow A), so that the discharge efficiency is reduced.

Comparing Table 1 and Table 2 in consideration of such a structural difference, it can be understood that the results are different. That is, as the arrangement density of the ink discharge ports 13 is increased and the size of the ink discharge ports 13 is reduced in order to perform high-density printing, the size of each heating element 3 is reduced and the driving voltage is reduced. It is necessary to reduce the amount of ejection energy given to the ink 15 from each heating element 3, and the diameter of the ink ejection port 13 becomes smaller, so that the fluid resistance at the time of ink ejection becomes larger. For this reason, in the edge shooter type ink jet recording head having low ejection efficiency, it becomes gradually difficult to break down the meniscus in a state where the surface tension of the ink 15 and the external pressure are kept in an equilibrium state and eject the ink droplet 15b. . Therefore, in order to discharge ink at a high speed in an ink jet recording head that performs high-density printing exceeding 400 dpi, it is necessary to use a side shooter type ink jet recording head 1.

Next, the results of examining the effect of the difference in the ink ejection speed on the pixel diameter on the recording paper surface will be described. Table 3
Fig. 3 compares the sizes of pixels formed on the paper surface in the side shooter method and the edge shooter method. The ink used was the same as that described above, and a matte coated paper NM made by Mitsubishi Paper Mills was used as the recording paper. Note that the pixel diameters shown in Table 3 are average values of the number of measurement samples n (n = 50).

[0038]

[Table 3]

As can be seen from the above, even if the ink jet recording heads have the same arrangement density, printing by the side shooter method with a high ink ejection speed is about 90%.
Can be obtained. This is advantageous when very high-definition recording is performed as in the present invention. In other words, by discharging ink at a high speed, it is possible to land on the target paper very stably even when flying, and because the discharge speed is high, the pixel diameter is unlikely to spread even when landing on the paper, Since the bleeding is difficult, very high quality printing is performed.

Next, one of the features of the ink jet recording head 1 according to the present invention, the distance from the surface of the heating element 3 to the outer surface of the ink ejection port 13 and the lid member 12
The thickness dimension of the portion where the ink ejection port 13 is formed will be described. In order to efficiently transmit the propulsive force of the ink ejection by the generated air bubbles 16 to the ink 15 and eject the ink 15 from the minute ink ejection port 13, as shown in FIG. The distance "h" to the outer surface has a significant effect. Further, in the figure, “t” is a thickness dimension of a portion of the lid member 12 where the ink ejection port 13 is formed.

Here, Table 4 shows the results of measuring the ejection speed of the tip of the ink droplet to be ejected by experimentally producing an ink jet recording head in which the above-mentioned distance "h" and dimension "t" were changed. . In addition, the ink jet recording head used here has one ink ejection port 13 like the ink jet recording head prototyped for performing the measurement in Table 2.
Table 4 has four barriers 14 around the periphery.
Are set according to the case where the measurement is performed. The ink discharge ports are formed by processing a polysulfone resin sheet with an excimer laser.

[0042]

[Table 4]

From this measurement result, the printing density was 400 dp.
In an ink jet recording head that performs high-density printing such as i or beyond, the distance “h” from the surface of the heating element 3 to the outer surface of the ink ejection port 13.
Is required to be 70 μm or less. In addition,
Even when “h” is 70 μm or more, for example, 90 μm, ink droplets can be ejected, but the ejection speed of the tip of the ink droplet is 10 m / s or less, the ejection force is weak, and the ink droplet is easily affected by disturbance. This is disadvantageous for performing stable printing.

In the case where printing is performed at a very high density as in the case of the ink jet recording head according to the present invention, the processing accuracy of the ink discharge ports 13 is increased and each ink discharge port 1 is formed.
No. 3 requires no variation, and Table 5 shows the results of measuring the processing accuracy of the ink discharge ports 13. The material used was a sheet of polysulfone resin, and the thickness of the material was changed to form an ink ejection port 13 having a diameter of 28 μm using an excimer laser, and the dimensional accuracy was examined. In addition, since the size of the ink ejection port 13 could not be measured with high precision using an optical length measuring device, a simple head was manufactured, and pure water was ejected from the ink ejection port 13 for a certain period of time to discharge the ink. By collecting pure water and measuring its weight, the ink discharge port 1
It is converted to the caliber of 3.

[0045]

[Table 5]

From this measurement result, it is understood that the dimensional accuracy of the formed ink discharge port 13 is within ± 0.3 μm by setting the thickness “t” of the polysulfone resin to 50 μm or less. In general, very small pixels
In order to print at a high density exceeding dpi, the variation in the diameter of the ink discharge ports 13 needs to be at least within ± 0.5 μm. From the measurement results shown in Table 5, the thickness of the material is reduced. This can be achieved by setting it to 10 μm to 50 μm.

Next, a description will be given of a measurement result on the effect of the barrier 14 on the ejection efficiency of the ink 15. 4
When high-density printing exceeding 00 dpi is performed, the structure around the ink ejection port 13 is important, as well as the difference in ejection structure as shown in Tables 1 and 2. This occurs in an ink jet recording head that performs relatively coarse printing with a printing density of 400 dpi or less, because the size of the ink discharge port is large, the fluid resistance at the time of ink discharge is small, and the size of the heating element is large. The propulsive force for ejecting ink is large because the bubbles generated are large enough. On the other hand, in the case of an ink jet recording head that performs high-density printing exceeding 400 dpi, the size of the ink ejection port and the heating element is reduced, and the ink ejection time is reduced. This is because the fluid resistance increases and the driving force for ejecting the ink decreases. Therefore, by forming the barrier 14 as shown in FIGS. 3 and 8 around the ink discharge port 13, the propulsive force of the bubble can be efficiently transmitted to the ink discharge port 13 side without escaping in the lateral direction. .

Here, Table 6 shows the results of measuring the ejection speed of the leading end of the ink droplets ejected by experimentally producing an ink jet recording head in which the printing density was changed and the number of barriers 14 was changed. It should be noted that two barriers 14 are in the state shown in FIG. 3 and four barriers 14 are in the state shown in FIG. The conditions for ejecting ink droplets are set in accordance with the above-described measurement, and the distance “h” is set to 50 μm and the thickness “t” is set to 20.
It is set to μm.

[0049]

[Table 6]

From this measurement result, the printing density was 400 dp.
In the ink jet recording head i, an ejection speed of 10 m / s or more can be obtained even without the barrier 14, but in the case of the ink jet recording head having a printing density exceeding 480 dpi, the ejection is performed without the barrier 14. Since the speed becomes slow and the influence of disturbance becomes liable, it becomes difficult to perform stable printing. On the other hand, the printing density was 480
In an ink jet recording head that performs high-density printing exceeding dpi, a sufficiently high ejection speed can be secured by providing the barrier 14, and the number of the barriers 14 increases the ejection speed more than two. be able to.

From the above, it has been found that it is effective to provide the barrier 14 when performing high-density printing.
On the other hand, since it is necessary to secure a space for positioning the barrier 14 between the adjacent heating elements 3, the heating elements 3
Has to be reduced. Therefore, as shown in FIG. 10, the shape of the heating element 3 is formed to be vertically long in a direction orthogonal to the arrangement direction of the heating elements 3 (that is, the arrangement direction of the ink ejection ports 13). Thereby, the heating element 3
In this case, a sufficient heat generation amount can be obtained by increasing the surface area of the first heating element, and a space for locating the barrier 14 between the adjacent heating elements 3 can be secured. Even when high-density printing is performed as in the present invention, the ink discharge ports 13 can be arranged in a line at the same density as the final printing density.

[0052]

According to the ink jet recording apparatus of the first aspect of the present invention, in an ink jet recording apparatus for performing high-density printing of 480 dpi or more, the size of the ink ejection port is set to φ40 μm or less, and the energy for giving ejection energy to the ink. Since the surface of the working portion and the ink discharge port are substantially parallel, the surface of the energy working portion, which applies the discharge energy to the ink, is substantially parallel to the ink discharge port. Energy can be efficiently used for ink ejection. Therefore, even in an ink jet recording apparatus that performs unprecedented high-density printing in which the size of the ink ejection port is reduced to φ40 μm or less, ejection from the ink ejection port is not possible. The ink ejection speed can be as high as 10 m / s or more. It is possible to discharge with a constant can be obtained with high pixel position accuracy in the plane position can be realized a high-quality mark copy.

According to the second aspect of the present invention, in the ink jet recording apparatus according to the first aspect, the energy applying section applies heat energy to the ink from its surface to generate bubbles in the ink. Since the ink is ejected in a direction substantially perpendicular to the surface of the energy application section by the action force of the bubble, the action force of the bubble generated in the ink can be used for ink ejection without waste, which has not been available in the past. Even in an ink jet recording apparatus that performs high-density printing, the ejection speed of the ink ejected from the ink ejection port can be increased to 10 m / s or more, and the ink can be ejected stably at a high speed. As a result, high pixel position accuracy in the paper position can be obtained, and high-quality printing can be realized.

According to the third aspect of the present invention, in the ink jet recording apparatus according to the second aspect of the present invention, since the size of the heating element is 45 μm × 45 μm or less,
By reducing the size of the ink ejection port, the heating element can be reduced in size, and the working force of the bubbles generated in the ink is used for ink ejection without waste. Discharge can be performed favorably. Further, the size of the heating element is set to 45 μm × 45 μm = 20.
Even when the thickness is 25 μm ² or less, the ink is stably ejected at a high speed at a high speed, and is more efficient than a head having another configuration (a head configured to discharge the ink in a direction substantially parallel to the surface of the heating element). It can be an energy acting part.

According to the fourth aspect of the present invention,
In the ink jet recording apparatus according to the invention described in 2 or 3, the ink discharge ports are perforated by excimer laser processing on the resin sheet, and the thickness of the resin sheet at the portion where the ink discharge ports are perforated is 10 μm to 50 μm. The dimensional accuracy of the outlet can be increased, and the dimensional accuracy of the ink ejection port can be increased, so that the mass of the ink ejected from the ink ejection port can be made uniform, and the pixel diameter on the paper becomes uniform. Therefore, the image quality can be improved.

According to the fifth aspect of the present invention, in an ink jet recording apparatus provided with an ink jet recording head having an ink discharge port for discharging ink and an energy action section for applying discharge energy to the ink, the ink jet recording head is used for printing. Density is 400dpi-800d
pi, an ink ejection port is formed on the side facing the energy application section, ink is ejected in a direction substantially perpendicular to the energy application section, and printing is performed. 40 μm distance to the surface
Since the thickness is set to about 70 μm, by discharging the ink in a direction substantially perpendicular to the energy application section, the ejection energy given to the ink from the energy application section can be efficiently used for the ejection of the ink. Since the distance from the surface of the ink ejection port to the outer surface of the ink ejection port is 40 μm to 70 μm, the ejection speed of the ink ejected from the ink ejection port can be as high as 10 m / s or more. And high pixel position accuracy in the paper position can be obtained, and high quality printing can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an ink jet recording head according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view thereof.

FIG. 3 is a perspective view of the lid member as viewed from the inside.

FIG. 4 is an explanatory diagram showing the principle of ink ejection in a side shooter type ink jet recording head.

FIG. 5 is a vertical sectional front view showing the structure of a heating element substrate in detail.

FIG. 6 is an explanatory view showing the principle of ink ejection in an edge shooter type inkjet recording head.

FIG. 7 is an explanatory diagram showing a part of the enlarged view.

FIG. 8 is a perspective view showing a state in which four barriers are formed around an ink discharge port.

FIG. 9 is a vertical sectional front view showing a peripheral portion of an ink discharge port in a cross section.

FIG. 10 is a plan view showing a positional relationship between a heating element and barriers arranged at high density.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink jet recording head 3 Energy action part, heating element 13 Ink ejection opening 15 Ink

Claims (5)

[Claims] In an ink jet recording apparatus for performing high-density printing of 480 dpi or more, the size of an ink ejection port is set to φ40 μm or less, and the surface of an energy application section that applies ejection energy to ink is substantially parallel to the ink ejection port. An ink jet recording apparatus, comprising: 2. The energy application section is a heating element that applies thermal energy to the ink from its surface to generate bubbles in the ink, and the energy of the bubbles acts in a direction substantially perpendicular to the surface of the energy application section. The ink jet recording apparatus according to claim 1, wherein the ink is ejected. 3. The heating element has a size of 45 μm × 45.
3. The ink jet recording apparatus according to claim 2, wherein the diameter is not more than μm. 4. An ink discharge opening is formed by excimer laser processing in a resin sheet, and the thickness of the resin sheet at a portion where the ink discharge opening is formed is 10 μm to 50 μm.
The ink jet recording apparatus according to claim 1, 2 or 3, wherein 5. An ink jet recording apparatus comprising an ink jet recording head having an ink discharge port for discharging ink and an energy action section for applying discharge energy to the ink, wherein the ink discharge port is provided on a side facing the energy action section. And printing is performed by ejecting the ink in a direction substantially perpendicular to the energy application section, and a printing density of 400 dpi to 800 dpi.
The distance from the surface of the energy applying section to the outer surface of the ink ejection port is 4
An ink jet recording apparatus having a thickness of 0 μm to 70 μm.