JPH0469248A - Ink jet printer head - Google Patents

Abstract

PURPOSE:To eliminate a layer exclusively for an ink supply passage and make an ink supply excellent by arranging an orifice having a fine tip and an extended end and a partition of a pressure chamber having a tip periphery smaller than the end so as to face each other through an ink supply passage which opens to the whole peripheral direction. CONSTITUTION:An orifice 31 having a fine tip and an extended end is formed on a second plate 30 without supply passage layer and a partition 32 of a pressure chamber 9 whose tip periphery is smaller than the end is formed on a first plate 33. In a state that the first and second plates 33 and 30 are connected integrally, an ink supply passage 34 is formed in a clearance between the tip of the partition 32 of the pressure chamber 9 and the end of the orifice 31. An ink jet printer head 29 having such a constitution deflects a pressure generated at a surface of a heat generating resistor 7 by the partition 32 of the pressure chamber 9 so as to eject ink drips from the orifice 31 with a high efficiency. Thus, a layer dedicated to form the ink supply passage is not necessary to be manufactured and the fluid characteristic of the ink and the response characteristic will be excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an inkjet printer head such as a bubble jet type or a piezo type.

2. Description of the Related Art In recent years, inkjet printer heads have been developed as printer heads that are quiet and capable of high-density printing. this is,
Ink droplets or ink vapor are ejected from an orifice using a predetermined pressure generating means and fixed on the printing paper.In addition to the piezo method that uses an electrostrictive element as the pressure generating means, there are also thermal types that use a heating element as the pressure generating means. A method such as a bubble jet method and a bubble jet method have been proposed. These methods can apply existing technology related to thermal heads, and are therefore expected to be a method for easily obtaining high-performance inkjet printer heads.

Here, a bubble jet type inkjet printer head is one in which a part of the ink filled in a pressure chamber behind an orifice is instantaneously heated and evaporated, and the pressure caused by the volume change of the bubbles formed is used to push ink droplets out of the orifice. It is designed to be discharged.

There are various types of bubble jet inkjet printer heads.
The inkjet printer head disclosed in the above publication has a structure in which a flat member with a long groove serving as an orifice is attached to a substrate that has a structure similar to that of existing thermal heads. By selectively driving the heating resistor to generate heat, bubbles are generated in the ink within a predetermined orifice, and ink droplets are ejected. Note that the generation and disappearance of such bubbles takes place in a minute time of about μs,
As the pressure of the ink rapidly rises and falls within this range of J-II, the ink ejected from the tip of the orifice becomes ink droplets and flies.

However, in the above-mentioned inkjet printer head, since the orifice has a straight tube shape, the pressure change of the ink acts in the front and back direction, resulting in excessive pressure loss.

Therefore, as devices that have solved this problem, there are devices disclosed in Japanese Patent Publication No. 63-6356, Japanese Patent Publication No. 63-6357, and Japanese Patent Publication No. 63-6358. For example, in the inkjet printer head disclosed in Japanese Patent Publication No. 63-6356, a flow path is formed that is bent at a substantially right angle at the heating resistor part, so that changes in ink pressure can favorably affect the jetting direction of ink droplets. That's what I do.

However, in an inkjet printer head with a curved flow path as described above, the direction of pressure change and the direction of flow during continuous ejection are asymmetrical with respect to the fine details of the orifice, so the flight direction of the ejected ink droplets is bent. It ends up.

As a countermeasure to this problem, it has been proposed to displace the relative position of the pressure generating means with respect to the orifice, but the optimal value of this displacement may vary depending on factors such as changes in ink viscosity due to temperature changes and aging. They are different, and it is difficult to perform accurate fluid analysis, so it is not practical.

Furthermore, JP-A-58-8659 and JP-A-59-2
The inkjet printer head disclosed in Japanese Patent No. 07261 has a structure in which a pressure chamber partition wall surrounding the heat generating resistor is formed on a substrate on which the heat generating resistor is formed, and an orifice plate is bonded thereon. The flow path is located symmetrically with respect to the heating resistor and the orifice, so that the bending of the ink droplet in the ejection direction can be eliminated.

However, in these inkjet printer heads, the heating resistor and the flow path are located on the same plane, so the pressure generated on the surface of the heating resistor flows out of the flow path and is effectively transmitted to the orifice. Not done.

Therefore, as an inkjet printer head that solves the above-mentioned problems such as bending of the ejection direction of ink droplets and reduction in pressure transmission efficiency, the present applicant has proposed a patent application for patent application No. 1-29
There is a device proposed in No. 4240. Therefore, this inkjet printer head was used as the first technology as a prior art.
This will be explained based on FIGS. 1 to 16. The main structure of this inkjet printer head 1 is such that a substrate 2, a pressure chamber layer 3, a supply path layer 4, and an orifice plate 5 are sequentially laminated, as illustrated in FIGS. 13 and 14. And the 111th i! As illustrated in FIG. 1, orifices 6 continuously formed in an array on this orifice plate 5 and a heating resistor 7 which is a pressure generating means formed on the surface of the substrate 2 are located coaxially. A pressure chamber 9 symmetrical with respect to the axis of the orifice 6 is formed by the pressure chamber layer 3 in which a rectangular annular partition wall 8 is formed with the heat generating resistor 7 approximately at the center. The orifice 6 is formed by the supply path layer 4 whose opposing portions are open.
An ink supply path 10 is formed that is open in the circumferential direction with respect to the axis of the ink supply path 10 . In this inkjet printer head 1, an ink storage chamber 11 is formed between the partition walls 8 of the pressure chamber layer 3, and an ink supply hole 12 communicating with this ink storage chamber 11 is formed in the substrate 2. .

Next, the structure of each part of the inkjet printer head 1 having the above structure will be described in detail below along with the manufacturing method.

First, as illustrated in FIG. 15, the substrate 2 has a thickness of O.
It is made of a Si wafer, etc., which has good heat dissipation of about 0.01 to 1.0 (an), and has a thickness of 2.0 (μm) on the surface.
A heat storage layer 13 made of Sio, Al, O, etc. is formed. Next, a Ta layer with a thickness of 0.4 (μm) is placed on top of this.
By sputtering AQ or TaN and patterning it by etching, the heating resistor 7 is formed to a thickness of 0.4 (
Similarly, a resistance layer 14 with a thickness of 0.5 (μm) is formed.
) A common electrode 15 and individual electrodes 16 each made of AQ are formed. Next, on top of these, a first protective film 17 made of Si, N4 or Sin with a thickness of about 0.3 (μm) and a film made of Ta having good cavitation resistance and a thickness of about 0.2 (μm) are applied. CV D (C
The layers are sequentially stacked using a chemical vapor deposition method or sputtering.

The shape of the heating resistor 7 formed as described above is, for example, a square of 60 x 60 (μm). Furthermore, in the following description, the substrate 2 means the substrate on which the above-mentioned members 13 to 18 are formed.

Then, the pressure chamber layer 3 is formed on the substrate 2 on which the heating resistor 7 and the like are formed as described above. This pressure chamber layer 3 is shown in FIG. 16(a).

As illustrated in (b), photosensitive polyimide 19, which is one of the photosensitive resins with a thickness of 30 (μm), is coated on the substrate 2 and semi-cured (dried), and is photo-patterned. A partition wall 8 and an outer peripheral portion 20 are formed, and the pressure chamber 9 and the ink storage chamber 11 are provided.

Further, the ink replenishment hole 12 is formed in the substrate 2 through the ink storage chamber 11 by laser processing.
The shape of the pressure chamber 9 formed as described above is 70 x 70 (μm) centered on the heating resistor 7.
The width of the partition wall 8 is 30 (μm).
It has become.

Here, the pressure chamber layer 3 formed on the substrate 2 as described above will be referred to as a first plate 21. The plate that is integrally joined to the second plate 22 will be referred to as the second plate 22.

Therefore, the structure of this second plate 22 will be explained below. First, as illustrated in FIG. 16(C), a mask 24 with a predetermined pattern is attached to a jig substrate 23 such as an SUS substrate, and Ni is electroformed to a thickness of 40 (μm). The orifice plate 5 is formed by utilizing the fact that the orifice 6 is raised around the mask 24 and has the orifice 6 whose tip end is narrower than the end end and whose minimum diameter is about 50 (μm). After this is peeled off from the jig substrate 23 and the mask 24 is removed, Au plating (not shown) to a thickness of 0.1 (μm) is performed to fix it onto the jig substrate 23 again. Therefore, as illustrated in FIG. 16(d), an uncured photosensitive polyimide 25 is placed on the orifice plate 5 to a thickness of 10 mm.
(μm), as illustrated in FIG. 16(e),
This is processed in the same manner as the pressure chamber layer 3 described above to form the ink supply path 10 centered on the orifice 6. The second plate 22 is formed by removing the orifice plate 5, on which the supply path layer 4 is integrally formed, from the jig substrate 23 and cutting it into a predetermined shape.

Then, as illustrated in FIGS. 16(f) and (g), the first and second plates 21 and 22 manufactured as described above are
Adhesive material (not shown) is attached to at least one outer peripheral portion 20 of the
The inkjet printer head 1 is manufactured by coating the orifice 6 and the heating resistor 7 with each other and pressing them together with their axes aligned.

In such a configuration, this inkjet printer head l is provided with a drive circuit (not shown) for each electrode 15,16.
is connected to the ink tank (
(both not shown) are connected and, as illustrated in FIG. 11, are arranged to face the printing paper 26 that moves relatively in the sub-scanning direction. Therefore, this inkjet printer head 1 is
When power is applied from each electrode 15.degree. 16 and the heating resistor 7 generates heat, the ink 27 in contact with it evaporates and bubbles 28 are generated. At this time, the propagation direction of the pressure change in the ink 27 due to the generation of the bubbles 28 is regulated by the pressure chamber 9 and directed toward the orifice 6. Therefore, the power supply from the electrodes 15, 16 is stopped in synchronization with the timing at which the ink 27 is ejected from the orifice 6, the temperature of the heating resistor 7 decreases, and the bubbles 28 contract. Then, due to a change in the pressure of the ink 27 caused by the contraction of the air bubbles 28, a part of the ink 27 protruding from the orifice 6 is cut off, and this becomes an ink droplet 27a and flies. Therefore, by selectively driving the heating resistor 7 to generate heat and causing the ink droplets 27a to fly from a predetermined orifice 6, an image can be formed on the surface of the printing paper 26 that moves relatively in the sub-scanning direction.

Note that each pressure chamber 9 is supplied with ink 27 which is sequentially replenished from the ink supply hole 12 from the ink storage chamber 11 via the ink supply path 10.

In this inkjet printer head l, the shape of the ink supply path lO and the pressure chamber 9 and the position of the heating resistor 7 are symmetrical with respect to the axis of the orifice 6, so that pressure changes in this part are symmetrical. The action direction and the feel direction are symmetrical, and the ink droplet 27a flies in the axial direction of the orifice 6.

Furthermore, in this inkjet printer head 1, the heating resistor 7 on the substrate 2 is surrounded by the partition wall 8, and the orifice 6
Since it is opposed to the heating resistor 7, the pressure generated on the surface of the heating resistor 7 is transmitted to the orifice 6 without flowing to the side, and the drive efficiency is good and it is possible to save the labor of the equipment. .

Problems to be Solved by the Invention In the above-mentioned inkjet printer head l, the arrangement of each part is symmetrical with respect to the axis of the orifice 6, so that the ejection direction of the ink droplets 27a is not bent, and moreover, the heating resistor 7 is aligned with the partition wall 8. The pressure transmission efficiency is also good.

However, in the above-mentioned inkjet printer head 1, since the second plate 22 is formed of two layers, the orifice plate 5 and the supply path layer 4, productivity is reduced. here,
This supply channel layer 4 forms an ink supply channel 10 communicating from the ink storage chamber 11 to the pressure chamber 9, and if it is simply omitted, the leading edge of the partition wall 8 and the back surface of the orifice plate 5 will come into contact. Therefore, the ink 27 is not supplied into the pressure chamber 9.

Means for Solving the Problems A first plate on which at least a pressure generating means and a partition forming a pressure chamber are formed and a second plate on which at least an orifice is formed are joined together so that the pressure generating means and the orifice are formed. In the inkjet printer head that faces each other through a pressure chamber with which the ink supply path is communicated, an orifice is formed with a thin tip and a widened end, and the outer circumference of the leading edge of this orifice is smaller than the widened end. A partition wall of the pressure chamber was formed, and an ink supply path consisting of a gap opened in the entire circumferential direction was formed between the leading edge of the partition wall of the pressure chamber and the end of the orifice.

An orifice with a thin working tip and a widened end, and a partition wall of a pressure chamber whose outer periphery at a leading edge is /J% smaller than the end of this orifice form an ink supply path consisting of a gap that opens in the entire circumferential direction. Since they face each other through the ink supply channel, there is no need to manufacture a dedicated layer to form an ink supply path, and pressure can be transmitted from a pressure chamber with good ink replenishment to an orifice with good fluid characteristics.

Embodiment An embodiment of the present invention will be explained based on FIGS. 1 to 10. First, in the inkjet printer head 29 of this embodiment, as illustrated in FIG. 1, an orifice 31 having a narrow tip and a widened end is formed in a second plate 30 that does not have a supply path layer. , this orifice 31
The partition wall 32 of the pressure chamber 9 has a smaller outer circumference at its leading edge than at its distal end.
is formed on the first plate 33. In a state where these first and second plates 33 and 30 are integrally joined, an ink supply path is formed in the gap between the leading edge of the partition wall 32 of the pressure chamber 9 and the end of the orifice 31. 34 is formed.

Here, the partition wall 32 of the pressure chamber 9 of the first plate 33
is formed to a height of about 20 to 30 (μm), and is higher than at least 1/2 of the maximum height of the bubbles 28 generated on the surface of the heating resistor 7, so that the deflection of pressure is improved. . The thickness of approximately 50 (μ
m) said second plate 30 has an orifice 31 thereof;
The minimum pore diameter at the tip is about 50 (μm), and the maximum pore diameter at the end is about 150 (μm).

It is noted in this application that the second plate 30 having the orifice 31 having such a shape can be easily manufactured by using a jig substrate (not shown) in which a protrusion is formed by isotropic etching. This method is disclosed in Japanese Patent Application No. 126512/1996. Further, the other structure and manufacturing method are the same as those of the inkjet printer head 1 described above.

In such a configuration, this inkjet printer head 29, like the above-mentioned inkjet printer head 1, transfers the pressure generated on the surface of the heating resistor 7 to the pressure chamber 9.
The ink droplet 27a is deflected by the partition wall 32 and is ejected from the orifice 31 with high efficiency.

Here, in this inkjet printer head 29, the leading edge of the partition wall 32 of the pressure chamber 9 is located on the same plane as the end portion of the orifice 31, but the outer periphery of the partition wall 32 is located on the same plane as the orifice 31.
1, an ink supply path 34 communicating from the ink storage chamber 11 to the pressure chamber 9 is formed.

Moreover, with this inkjet printer head 29,
Since the orifice 31 has a shape with a narrow tip and a widened end, its fluid characteristics are good and pressure transmission efficiency is high.

In other words, in this inkjet printer head 29,
Although productivity is improved by omitting the supply channel layer 4, the supply of ink 27 to the pressure chamber 9 is good, and the fluid characteristics of the orifice 31 are also good, so it is possible to create a device with high performance and good productivity. It can be implemented.

Moreover, the inkjet printer head 29 of this embodiment
In this case, as illustrated in FIG. 5, the productivity of the first plate 33 is improved by omitting the patterning of the resistance layer 14 and forming the heating resistor 7 in the pattern of the electrodes 15 and 16. .

Here, an example of a practical method for manufacturing the first plate 33 as described above will be described in detail below. First, the thickness is about 0.5 (
The surface of the Si substrate 2 (m+) is thermally oxidized to a thickness of about 1.5
A heat storage layer I3 made of Sin with a thickness of about 3,000 μm is formed thereon, and a resistive layer 14 is uniformly formed by sputtering Tacit to a thickness of about 3,000 μm. The film was formed by sputtering and had a thickness of approximately 500 mm (
The Afi film of A) is patterned by photolithography to form each electrode 15 and 16. Then, on top of these, a thickness of about 4000 (A) is made by CVD method or sputtering method.
A first protective film 17 with high insulating properties made of Si, or 5iUx is formed, and then Ta or Ti, which has high cavitation resistance, is deposited to a thickness of about 1000 μm by sputtering or vapor deposition. Or a second protection made of Cr etc. [
form 18.

In addition, in the above-mentioned inkjet printer head 29,
Although the upper edge of the partition wall 32 of the pressure chamber 9 of the first plate 33 and the back surface of the second plate 3o are located on the same plane, the present invention is not limited to the above structure. , as illustrated in FIG. 6(a), the partition wall 3 of the pressure chamber 9
The inkjet printer head 35 is designed to improve the efficiency of supplying the ink 27 into the pressure chamber 9 by separating the upper edge of the second plate 30 from the back surface of the second plate 30, and the inkjet printer head 35 shown in FIG.
As illustrated in b), an inkjet in which the upper edge of the partition wall 32 of the pressure chamber 9 is located within the orifice 31 of the second plate 30 to improve the efficiency of pressure transmission from the pressure chamber 9 to the orifice 31. A printer head 36 or the like may also be implemented. Therefore, when actually manufacturing the device, it is necessary to use the inkjet printer head 29, 3 as described above.
5.36 may be selected depending on the viscosity of the ink 27, the specifications of the equipment, etc.

Further, in the above-described inkjet printer head 29, it is assumed that the partition wall 32 of the pressure chamber 9 is formed into a square cylindrical shape, as illustrated in FIG. 7, but the present invention is not limited to the above structure. The shape of the pressure chamber 9 should be symmetrical with respect to the axis of the orifice 31.
As exemplified in the figures and FIG. 9, cylindrical or polygonal cylindrical partition walls 37, 38, etc. can also be implemented. Further, in the above-mentioned inkjet printer head 29, the orifice 31 was explained assuming a conical shape, but it can also be implemented with, for example, a square pyramid shape, a dome shape, or a combination of these shapes. be.

Furthermore, in the above-described inkjet printer head 29, as illustrated in FIG. 10(a), the partition wall 3 of the pressure chamber 9
Although the heat generating resistor 7 is surrounded by the heat generating resistor 7 as an example in 2, the present invention is not limited to the above structure, and can function as long as most of the heat generating resistor 7 is located within the partition wall 32 of the pressure chamber 9. It is also possible to form the partition wall 32 of the pressure chamber 9 on the surface of the heating resistor 7, as illustrated in FIG. 1O(b).

Further, in the above-mentioned inkjet printer head 29, etc., a bubble jet type that uses the heat generating resistor 7 as a pressure generating means is exemplified, but the present invention is not limited to the above method, and the present invention is not limited to the above method. It is also applicable to a piezo system using a strain element.

Effects of the Invention As described above, the present invention provides a pressure generating means by joining a first plate in which at least a pressure generating means and a partition wall forming a pressure chamber are formed and a second plate in which at least an orifice is formed. In an inkjet printer head, where the and orifice face each other via a pressure chamber with an ink supply path in communication, the orifice is formed with a narrow tip and a widened end, improving the fluid characteristics of the orifice and reducing ink droplets. is discharged well, and the outer circumference of the leading edge of the orifice is smaller than the expanded end of the orifice. By forming an ink supply path consisting of gaps that open around the entire circumference, there is no need to create a dedicated layer to form the ink supply path, and the pressure chamber allows for good ink replenishment, resulting in good fluid characteristics. This has advantages such as being able to transmit pressure to an orifice, and manufacturing an inkjet printer head with good fluid characteristics and responsiveness with good productivity.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional side view showing an embodiment of the present invention, Fig. 2 is a plan view with each part exploded, Fig. 3 is an exploded perspective view, Fig. 4 is a perspective view, and Fig. 5 is a vertical cross-sectional side view of main parts. Figure 6 is a vertical sectional side view showing the first and second modified examples, Figure 7 (a) is a plan view of the main part, Figure 7 (b) is a side view, and Figure 8 (a) is the 8(b) is a side view, and FIG. 9(b) is a plan view of the main part showing the third modification.
a) is a plan view of the main part showing the fourth modification, FIG. 9(b)
is a side view, Figure 10 (a) is a plan view of the main part, Figure 10 (
b) is a plan view showing the fifth modification, and FIG. 11 is a plan view of the fifth modification.
12 is an exploded plan view of each part, FIG. 13 is an exploded perspective view, FIG. 14 is a perspective view, and FIG. 15 is an essential part. A vertical sectional side view of the section, and FIG. 16 is a manufacturing process diagram. 7... Pressure generating means, 33... Pressure chamber, 29, 35
゜36...Inkjet printer head, 30...
・Second plate, 31... Orifice, 32, 37
゜38...Partition wall, 33...First plate, 34.
...Ink supply path Applicant Tokyo Electric Co., Ltd. Figure 32 (a) (b) Figure 5 J) Figure 7 J) ○ Figure 1q Figure (b) (b) (b) , %, IO increase (a) ( b) U JZ diagram (a)

Claims (1)

[Claims] A first plate on which at least a pressure generating means and a partition wall forming a pressure chamber are formed and a second plate on which at least an orifice is formed are joined together so that the pressure generating means and the orifice are in communication with each other through an ink supply path. In the inkjet printer heads that face each other across the pressure chamber, an orifice is formed with a narrow tip and a widened end, and the partition wall of the pressure chamber has a smaller outer circumference at its leading edge than the widened end of the orifice. An ink jet printer head characterized in that an ink supply path consisting of a gap opened in the entire circumferential direction is formed between the leading edge of the partition wall of the pressure chamber and the end of the orifice.