JPH0524200A - Ink jet head - Google Patents

Abstract

PURPOSE:To obtain an ink jet head having good printing characteristics by using a new orifice structure. CONSTITUTION:An ink jet head consists of a heater substrate 2 provided with a plurality of heaters 3 and a channel substrate 1 provided with ink flow paths. On a nozzle surface, a slit-form groove having a width larger than that of a nozzle port 10 is formed over the plurality of nozzle ports 10 in a nozzle arrangement direction as a common orifice forming part 17. Because a thin ink layer is formed on the common orifice forming part, ink is applied all over the periphery of an ink drop forming part. In this manner, an ink drop may not be caught by a part of the periphery of the nozzle port 10, but can be delivered in a predetermined direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head having an ink flow path and / or an ink ejection port formed by adhering two or more substrates together and having an improved ink orifice portion (ink holding portion). It is about the head.

[0002]

2. Description of the Related Art Non-impact recording methods have been widely adopted in recent years in printers and other output methods because of their low noise. Among them, the inkjet recording method is
This is a printing method that has attracted attention because it has good coloring properties of ink, and has the potential for cost reduction and size reduction.

An ink jet head of this system is disclosed in JP-A-61-230954 and JP-A-1-166965.
It is usually composed of a heater substrate and a channel substrate, as described in Japanese Patent Laid-Open Publication No. Hei. The manufacturing method will be described.

On a Si substrate, which is a polished wafer, SiO ₂ is deposited as a heat storage layer, and a poly is used as a heater.
After depositing -Si, patterning is performed. Further, Al to be the wiring is patterned, a heater and a protective layer for the wiring are deposited, and patterned to form a heater substrate. Further, a pit layer may be formed on it by using photosensitive polyimide.

On the other hand, an ink flow path (channel) and an ink chamber are formed by anisotropic etching (ODE) on a polished Si substrate, which is another wafer, to produce a channel substrate.

After these two heater substrates and channel substrates are aligned, they are bonded and separated into one print head chip by dicing.

FIG. 8 is a perspective view in which a part of a print head chip having a pit layer manufactured by the above-mentioned method is cut. In the figure, 1 is a channel substrate, 2 is a heater substrate, 3 is a heater, 4 is a bubble, 5 is a pit, 6 is an ink chamber, 9 is an ink droplet, 10 is a nozzle opening, 11 is an electrode,
Reference numeral 12 is a bonding pad, and 13 is a photosensitive resin layer. In addition, in this figure, the illustration of the heater 3, the protective layer of the electrode 11 and the like is omitted. A plurality of heaters 3 is formed on the heater substrate 2, and the heaters 3 are formed on the channel substrate 1.
An ink flow path in which the nozzle port 10 is opened is formed corresponding to. Ink is held in each nozzle opening 10 to form an ink orifice portion separated for each nozzle opening.

In such an ink jet head, the material forming the nozzle openings has a great influence on the printing characteristics. FIG. 9 is a front view of the vicinity of the nozzle opening of FIG. As described above, the channel substrate 1 and the heater substrate 2 are formed of Si substrates, and the heater substrate 2 is provided with the photosensitive resin layer 13 such as photosensitive polyimide. Therefore, the nozzle opening 10 is surrounded by Si and the photosensitive resin, and therefore, the nozzle opening is made of different materials.

Different materials usually have different ink affinity. FIG. 10 is an explanatory diagram of a flying state of an ink droplet when an ink flow path and a nozzle opening are made of materials having different ink affinity. Since the photosensitive resin layer 13 has a high ink affinity and the channel substrate 1 has a low ink affinity, the ink droplets 9 tend to be biased toward the photosensitive resin layer 13 side, causing a deviation in the flight direction of the ink droplets. Or, since the tail of the ink droplet is bent, the shape of the print dot is disturbed and the print image quality is deteriorated.

As a countermeasure against this, Japanese Patent Laid-Open No. 58-17566.
As described in Japanese Patent Publication No. 6, it has been proposed to surface-treat the nozzle surface. However, when the surface treatment is performed by the surface treatment agent, it is very difficult to uniformly apply the surface treatment agent to the surface around the nozzle opening without the surface treatment agent entering the nozzle, The print quality cannot be expected.

As another method, as described in Japanese Patent Publication No. 25335/1990, a method of forming all nozzle openings with the same material such as a photosensitive resin has been proposed.
In FIG. 11, a photosensitive resin layer 13 is formed on the heater substrate 2 as a protective layer for the wiring portion, an ink flow path is formed on the top plate 15 by the photosensitive resin layer 14, and the both are bonded to form a nozzle. The mouth 10 is formed. In this case, since the ink flow path and the nozzle port are made of the same material, that is, a photosensitive resin, there is no difference in the ink affinity of the material around the nozzle port. However, in general, a material such as a photosensitive resin has high ink affinity and the shape of the nozzle opening has a corner portion, so that the tail of the ink droplet is easily pulled to any corner of the quadrangle. As a result, the print image quality deteriorated.

As shown in FIG. 12, there is also a method of forming a triangular groove in the channel substrate 1 and forming the triangular nozzle port 10 by the photosensitive resin layer 13 formed on the heater substrate 1. There was a problem for the same reason I did.

As a configuration for improving these problems,
There is a nozzle configuration described in "Hewlett Packard Journal" Vol. 36, No. 5. This is shown in FIG. (A) figure is a front view, (B) figure is BB sectional drawing of (A) figure. This nozzle structure is a so-called roof shooter type in which a circular nozzle opening 10 is formed in a nozzle plate 16 facing the heater 3. This configuration has a big problem that it is difficult to increase the density.

FIG. 14 shows an example of a roof shooter type. (A) figure is a front view, (B) figure is BB sectional drawing of (A) figure. This example is disclosed in JP-A-61-49734, JP-A-62-253456, and JP-A-63-2.
No. 72558, etc. This is a roof shooter type in which a slit-shaped nozzle opening 10 is formed in a nozzle plate 16. This structure is easy to make and can be highly densified. However, there is a problem that it is easily affected by the ink ejection of adjacent dots, and the ink ejection directionality in the slit direction is poor.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an ink jet head having good printing characteristics by using a novel orifice structure. To do.

[0016]

According to a first aspect of the present invention, in an ink jet head in which two or more substrates are bonded to each other to form an ink flow path and / or an ink ejection port, The ink orifice portion holding the ink is common to a plurality of ink flow paths. In the invention of claim 2, in the invention of claim 1, a plurality of ink streams are provided. ink orifice portion which is common to road and ink affinity surrounding each I _O, when the I _R, is characterized in that the set to be I _O> I _R.

The ink orifice portion, which is common to a plurality of ink flow paths, can be formed in a concave shape in a direction orthogonal to the arrangement direction of the ink flow paths. As a method of forming an ink orifice portion that is common to a plurality of ink channels in a concave shape in a direction orthogonal to the ink channel array direction, a film provided with slits corresponding to the ink channel array direction Alternatively, a method may be used in which the plate is bonded to the surface on which the ink flow path end surface is exposed. in this case,
The film or plate may be formed of a material having a higher ink repellency than the surface in which the ink flow path and the end surface of the ink flow path are exposed. Alternatively, the film or plate may be subjected to an ink repellent treatment before being joined to the surface where the ink flow path end surface is exposed.

[0018]

According to the present invention, in the ink ejection portion, the ink orifice portion that holds the ink is common to the plurality of ink flow paths, so that the common ink orifice portion has a thin ink A layer is formed. Ink drops
Although it is ejected so as to break through this thin ink layer,
Since the periphery of the portion where the ink droplet is formed is ink, the ink droplet can be ejected in a predetermined direction without being attracted to any of the periphery of the nozzle opening.

The ink affinity of the ink orifice portion common to a plurality of ink flow paths and its surrounding area is I
_{By setting O O} and I _R such that I _O > I _R , the ink is attracted by the common ink orifice portion, and the ink can be held well in this portion. Become.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is for explaining a first embodiment of the present invention. FIG. 1A is a front view and FIG. 1B is a sectional view taken along line BB in FIG. In the figure, 1 is a channel substrate, 2 is a heater substrate, 3 is a heater, 5 is a pit, 6 is an ink chamber, 10 is a nozzle port, 13 is a photosensitive resin layer, and 17 is a common orifice forming part. In this embodiment, a plurality of heaters 3 are formed on the heater substrate 2, and on the substrate,
A photosensitive resin layer 13 in which the heater portion is opened and pits 5 are formed is provided. A groove corresponding to the heater 3 is formed as an ink flow path in the channel substrate 1 and communicates with the ink chamber 6. An inkjet head is configured by joining these two substrates. The opening of the ink flow path serves as a nozzle surface, and a slit-shaped groove having a width larger than that of the nozzle opening 10 is formed on the nozzle surface in the nozzle arrangement direction so as to form a common orifice. It is part 17. This common orifice forming part 1
By 7, the ink holding state is formed across the plurality of nozzle openings 10.

The depth L _D and width H _D of this groove are selected so that L _D <H _n <H _D with respect to the height H _n of the nozzle opening. Further, when the nozzle pitch is P _N , it is preferable that L _D <H _n <H _D ≦ 2 × P _N. In this example, dimensions having the following relationships were selected and good results were obtained. L _D : H _n : H _D : P _N = 1: 12: 30: 18

FIG. 2 is a plan view of FIG. 1 seen from above.
In the figure, 1 is a channel substrate, 2 is a heater substrate, 6 is an ink chamber, 10 is a nozzle opening, 12 is a bonding pad,
18 is a dummy nozzle. In this embodiment, three dummy nozzles 18 are arranged on both sides of the print nozzle. The dummy nozzle 18 is not driven during printing. Therefore, the heater of this nozzle may be omitted. The length W _D of the common orifice forming portion is W _P <W _N <W _D with respect to the width W _{P in} the arrangement direction of nozzles for printing and the width W _{N in} the arrangement direction of all nozzles including the dummy nozzles 18. Has become. W _H is the width of the head, W _R is the width of the ink chamber 6.

According to this structure, the ejection directionality of ink droplets is stable, clogging is less likely to occur, and reliability is high.

In a normal head, the ink supply for forming the ink orifice again after the ink is ejected is
It is performed only from the ink chamber through its own ink flow path. Further, if the width W _{R of the} ink chamber is not sufficiently large with respect to the width W _P of the nozzles for printing in the arrangement direction,
When driving at a high frequency, the ink supply could not catch up at both ends, causing print fading. However, according to the present invention, the ink is supplied from the adjacent nozzles through the common orifice forming portion, so that the ink refilling can be achieved in a short time. Further, if several dummy nozzles are provided at both ends, the width W _{R of the} ink chamber need not be so large. This makes it possible to reduce the outer dimensions of the head itself without deteriorating the printing characteristics.

FIG. 3 shows an ink ejection process in the ink jet head described with reference to FIG. In the figure, 3 is a heater, 4 is a bubble, and 17 is a common orifice forming part.
FIG. 6A shows a state where no drive signal is given to the heater. When the drive signal is applied to the heater 3,
Bubbles 4 are generated as shown in FIG. 7B, and bubbles 4 grow rapidly as shown in FIG. The force exerted by the growth of the bubbles 4 is directed in the ink ejection direction by the separated ink flow path, so that the ink in the common orifice forming portion formed sufficiently thin is pierced,
Ink ejects. (D) due to the protrusion of ink drops
As shown in FIG. 7E, the ink droplet 9 is ejected. At the same time, the bubbles 4 disappear in each separated ink flow path. In this case, the ink droplet 9 is ejected in a desired direction without being attracted to the offset portion of the nozzle opening 10 in the local area where the ink droplet is formed, because the ink droplet 9 is all around.

FIG. 4 is for explaining the second embodiment of the present invention. FIG. 4A is a front view and FIG. 4B is a sectional view taken along line BB in FIG. In the figure, the same parts as those in FIG. 14 is a photosensitive resin layer. In this embodiment, a photosensitive resin layer 13 having an open heater portion is provided on a heater substrate 2 provided with a plurality of heaters 3, and a recess serving as an ink chamber is provided on the channel substrate 1 to form an ink flow path wall. The photosensitive resin layer 14 is formed. The channel substrate 1 is bonded to the heater substrate 2 manufactured in this way, and the bonded two substrates are diced to manufacture an inkjet head.

According to this embodiment, the inside of the nozzle and the peripheral portion of the nozzle opening are all made of the photosensitive resin layer 1 having good ink affinity.
No. 3, 14 and the nozzle openings on the end faces are formed by patterning the photosensitive resin layer, so that unlike the dicing surface, a smooth surface with small surface roughness can be obtained. Further, the common orifice forming portion 17 includes the photosensitive resin layer 13,
The common orifice forming portion 17 is stably formed because the common orifice forming portion 17 is similarly formed by patterning 14. Also,
Since there is no photosensitive resin layer in the place to be diced and the same material is used, dicing is easy.

Further, as a method for stabilizing the ink in the common orifice forming portion, an ink repellent treatment may be applied to the surface around the common orifice portion. The ink repellency treatment can be commonly performed regardless of the first and second embodiments.

FIG. 5 is a sectional view of the essential parts of the third embodiment of the present invention. In the figure, 1 is a channel substrate, 2 is a heater substrate, 3 is a heater, 10 is a nozzle opening, 17 is a common orifice forming portion, and 19 is an ink repellent film. In this embodiment, the common orifice forming portion 1 of the inkjet head is used.
Ink repellent film 19 is formed around 7. The ink repellent film 19 is formed in a desired area by transferring a surface treatment agent. Generally, the surface treatment is the most difficult technique to prevent the treatment agent from entering the nozzle, but in this embodiment, as shown in FIG.
There is no problem even if there is some intrusion, but rather it becomes a preferable shape for stabilizing the common orifice forming portion. Therefore, a stable inkjet head that can achieve high image quality can be obtained by a simple surface treatment.

6A and 6B are for explaining a fourth embodiment of the present invention. FIG. 6A is a front view and FIG. 6B is a sectional view taken along line BB of FIG. In the figure, 1 is a channel substrate, 2
Is a heater substrate, 3 is a heater, 10 is a nozzle opening, 17
Is a common orifice forming part, S _A is an ink-philic area, S _B
Is an ink repellent area. In this embodiment, the common orifice forming portion 17 is configured by adjusting the affinity with the ink around the nozzle opening without changing the shape of the nozzle surface. That is, the vicinity of the nozzle opening is the ink-philic area S _A and the surrounding area is the ink-repellent area S _B. Since the area around the nozzle mouth is ink-philic,
The ink bleeds and the bleeding ink is confined in the ink repellent area to form a common orifice.

FIG. 7 is for explaining the fifth embodiment of the present invention. FIG. 7A is a front view and FIG. 7B is a sectional view taken along line BB of FIG. In the figure, the same parts as those in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted. Reference numeral 20 is an ink repellent film or an ink repellent plate. In this embodiment, the shape of the common orifice forming portion 17 is similar to that of the first and second embodiments, but the manufacturing method is greatly different. First, as in the prior art, a head is manufactured using the channel substrate 1 and the heater substrate 2, and an ink repellent portion is formed on the nozzle surface thereof. The ink-repellent portion can be formed by sticking a film or plate formed of an ink-repellent material, or a film or plate subjected to an ink-repellent treatment. At the time of sticking, there is almost no need to align the nozzles in the direction in which they are arranged, so the sticking process is easy. According to this embodiment, since the film or plate can be made ink-repellent independently, various treatment methods such as plasma treatment, plating treatment and vapor deposition treatment can be adopted.

It should be noted that, in the above-mentioned explanatory views of the embodiments, the illustration of the electrode portions, protective layers and the like not directly related to the present invention is omitted. The present invention is not limited to these examples, but includes all methods for achieving the conditions and configurations described in the claims.

[0033]

As is apparent from the above description, according to the present invention, by forming a common ink orifice in a plurality of nozzle openings, it is possible to eject ink droplets with good directionality. The nozzle is less likely to be clogged due to drying, and a stable inkjet head can be obtained. In addition, a shape and configuration that can be easily surface-treated can be adopted, and characteristics are not significantly affected by the material for forming the nozzle orifice and the quality such as chipping, so that the burden of the manufacturing process of the head can be greatly reduced. .

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of an inkjet head of the present invention.

FIG. 2 is a plan view of the inkjet head of FIG. 1 seen from above.

FIG. 3 is an explanatory diagram of an ink ejection process of the inkjet head of FIG.

FIG. 4 is an explanatory diagram of a second embodiment of the inkjet head of the present invention.

FIG. 5 is an explanatory diagram of a third embodiment of the inkjet head of the present invention.

FIG. 6 is an explanatory diagram of a fourth embodiment of the inkjet head of the present invention.

FIG. 7 is an explanatory diagram of a fifth embodiment of the inkjet head of the present invention.

FIG. 8 is a perspective view in which a part of a conventional inkjet head is cut.

9 is a front view of the vicinity of the nozzle opening of FIG.

FIG. 10 is an explanatory diagram of a flying state of ink droplets in a conventional inkjet head.

FIG. 11 is an explanatory diagram of a nozzle of an example of a conventional inkjet head.

FIG. 12 is an explanatory diagram of a nozzle of another example of a conventional inkjet head.

FIG. 13 is an explanatory diagram of a nozzle of another example of the conventional inkjet head.

FIG. 14 is an explanatory diagram of a nozzle of another example of a conventional inkjet head.

[Explanation of symbols]

1 channel substrate, 2 heater substrate, 3 heater, 5 pits, 6 ink chambers, 10 nozzle openings, 13
Photosensitive resin layer, 17 Common orifice forming part.

Claims (2)

[Claims] 1. In an ink jet head in which two or more substrates are bonded to each other to form an ink flow path and / or an ink ejection port, the ink ejection section, which holds ink, has a plurality of ink flow paths. An inkjet head that is common to both. 2. When the ink affinity in and around the ink orifice portion common to a plurality of ink flow paths is I _O and I _R , respectively, I _O > I _R The inkjet head according to claim 1.