JPH0447947A - Ink jet jprinter head - Google Patents

Abstract

PURPOSE:To reduce a pressure loss and make the drive efficiency excellent by forming a partition to make a pressure chamber surrounding pressure generating means from all-round direction, forming an inside face which nearly communicates the pressure chamber to an orifice, and forming on the partition a pressure transfer wall in which an ink supply passage with an outside circumference expanded rather than an inner side is formed symmetrically with respect to an axial core of the orifice. CONSTITUTION:In an ink jet printer head 53, a pressure generated on a surface of a heat generating resistor 31 and deflected toward an orifice 30 at a partition 54 is transferred to the orifice 30 along an inner face 58 of a pressure transfer wall 55 preferably without diffusing to side directions, so that ink drips are ejected from the orifice 30 with a high efficiency. Also, an orifice plate 29 is coupled to a substrate 26 by the partition 54 and the pressure transfer wall 55 of a pressure chamber 33, so that the rigidity of the whole device is high and the durability thereof is excellent. moreover, an occurrence of a breakdown of the partition 54 due to the pressure generated on the surface of the heat generating resistor 31 can be prevented.

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 an on-demand type.

Conventional technology In recent years, inkjet printer heads have been developed to instantly heat a portion of the ink filled in the pressure chamber behind the orifice to evaporate it, and then use the pressure generated by the volume change of the bubbles formed to push ink droplets out of the orifice. A bubble jet method was developed. Since this method can apply existing technology related to thermal heads, it is expected to be a method that can easily obtain a high-performance inkjet printer head.

As such a bubble jet type inkjet printer head, there are devices disclosed in Japanese Patent Publication No. 63-59911 and Japanese Patent Publication No. 63-59914. As illustrated in FIGS. 8 and 9, in this inkjet printer head 1, a groove cover 2 having continuous long grooves on the bottom surface is fixed on a flat substrate 3, and an orifice 4 is formed.
are formed in an array, and a supply chamber cover 5 having long grooves formed in the array direction is attached to the rear of the groove cover 2 to form a supply chamber 6 communicating with each orifice 4.

Here, a supply pipe 7 connected to an ink tank (not shown) is attached to the supply chamber 6, and a heating resistor 8 is connected to a common electrode 9 for each orifice 4 on the upper surface of the substrate 3. It is formed via the individual electrodes 10. Incidentally, these members 8 to 1O are formed to have substantially the same structure as an existing thermal head.

In this inkjet printer head 1 with such a configuration, each orifice 4 is filled with ink 11 supplied from the ink tank via the supply pipe 7 via the supply chamber 6. Therefore, the heating resistor 8 is selectively driven to generate heat by the electric power supplied from each electrode 9° 10, so that bubbles are generated in the ink 11 in the predetermined orifice 4, and ink droplets (both not shown) are ejected. be done. Note that the generation and disappearance of such bubbles takes place in a microscopic time of about μs, and as the pressure of the ink 11 rapidly rises and falls within this microscopic time, the ink 11 ejected from the tip of the orifice 4 becomes an ink droplet. and fly.

However, in the above-described inkjet printer head 1, since the orifice 4 has a straight tube shape, the pressure change of the ink 11 acts in the front-rear direction, resulting in low pressure efficiency.

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 12 disclosed in Japanese Patent Publication No. 63-6356, as illustrated in FIGS. By attaching it to the heating resistor 8, a flow path 14, which is an ink supply path bent at a substantially right angle, is formed. It is attached to the top surface.

In this configuration, the inkjet printer head 12 has a shape in which the flow path 14 is bent at a substantially right angle at the heating resistor 8, so that the pressure change of the ink 11 that occurs when bubbles are generated and disappears is suppressed by ink droplets. The pressure efficiency is improved by working well in the direction of injection. Note that in the illustrated drawing, ink droplets are ejected upward.

However, since pressure changes of the ink 11 are still conducted into the supply chamber 6, mutual interference tends to occur between the orifices 4 communicated via the supply chamber 6, and image quality tends to deteriorate.

Therefore, as illustrated in FIG. 12, the above-mentioned publication discloses that by forming a protrusion 17 in the long groove of the groove cover 2 forming the flow path 14, the pressure is transmitted from the heating resistor 8 to the supply chamber 6. Inkjet printer head 1 designed to reduce changes
8 is also disclosed.

However, it is actually difficult to form the above-mentioned convex portion 17 in the flow path 14, which is formed in the order of tens of micrometers, and the productivity of the device is extremely reduced, making it impractical. Not.

In the inkjet printer head 12.18 in which the flow path 14 is bent as described above, the direction of pressure change and the direction of flow during continuous ejection are asymmetrical with respect to the axis of the orifice 15. The flight direction of the ejected ink droplets is bent.

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 varies depending on factors such as temperature changes and changes in ink viscosity due to aging. However, it is difficult to perform accurate fluid analysis, so it is not practical.

Furthermore, the inkjet printer head 19 disclosed in JP-A-58-8659 and the JP-A-59207
In the inkjet printer head 20 disclosed in Japanese Patent No. 261, as illustrated in FIGS. 13 and 14, an orifice plate 22 is disposed on a partition wall 21 that surrounds a heating resistor 8 formed on a substrate 3. An apparatus is disclosed in which a plurality of flow passages 24, which are ink supply passages, are formed for - orifices 23. For example, in the orifice 23 in the middle of the inkjet printer head 19 and the inkjet printer head 20, the flow path 24 is located symmetrically with respect to the heating resistor 8 and the orifice 23, so it is possible to eliminate bending in the ejection direction of ink droplets. can. However, in these inkjet printer heads 19 and 20, the heating resistor 8 and the channels 14 and 24 are located on the same plane, so the pressure generated at the position of the heating resistor 8 is It is supposed to flow from orifice 2
3 is not well transmitted. For this reason, in these inkjet printer heads 19, 20, the driving efficiency of the device is reduced, and labor saving of the device is hindered.

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. 5 to 20. The main structure of this inkjet printer head 25 is such that a substrate 26, a pressure chamber layer 27, a supply channel layer 28, and an orifice plate 29 are sequentially laminated, as illustrated in FIGS. 17 and 18. Then, as illustrated in FIG. 15,
Orifices 30 continuously formed in an array on this orifice plate 29 and a heating resistor 31 which is a pressure generating means formed on the surface of the substrate 26 are located coaxially. A pressure chamber 33 symmetrical with respect to the axis of the orifice 30 is formed by the pressure chamber layer 27 in which a rectangular annular partition wall 32 is formed approximately at the center;
The supply path layer 28 is open at a portion facing the pressure chamber 33, and an ink supply path 34 is formed that is open in the entire circumferential direction relative to the orifice 30. In addition,
In this inkjet printer head 25, an ink storage chamber 35 is formed between the partition walls 32 of the pressure chamber layer 27, and an ink supply hole 3 communicating with the ink storage chamber 35 is formed.
6 is formed on the substrate 26.

Next, the structure of each part of the inkjet printer head 25 having the above-described structure will be described in detail below along with the manufacturing method. First, as illustrated in FIG. 19, the substrate 26 is formed of a Si wafer or the like having a thickness of about 0.1 to 1.0 (μm) and having good heat dissipation, and has a thickness of 2.0 μm on the surface thereof. 0(μ
m) heat storage layer 37 made of Sio, Al, O, etc.
form. Next, on top of this, a T with a thickness of 0.4 (μm)
By sputtering aAQ or TaN and patterning it by etching, the heating resistor 31 is formed to a thickness of 0.
A resistive layer 38 with a thickness of 4 (μm) is formed, and a resistive layer 38 with a thickness of 0.5 (μm) is similarly formed.
A common electrode 39 and individual electrodes 40 each having an AQ of .mu.m) are formed. Then, on top of these, a thickness of 0.3 (μm) is applied.
) and a second protective film 42 made of Ta having good cavitation resistance and having a thickness of 0.2 (μm) are formed by CVD or sputtering, respectively. Form layers in sequence.

Note that the shape of the heating resistor 31 formed as described above is, for example, a square of 60×60 (μm). Furthermore, in the following description, the substrate 26 means a substrate on which the above-mentioned members 37 to 42 are formed.

Then, the pressure chamber layer 27 is formed on the substrate 26 on which the heating resistor 31 and the like are formed as described above. As illustrated in FIGS. 20(a) and 20(b), this pressure chamber layer 27 is made of a 30 (μm) thick photosensitive resin coated on the substrate 26 and semi-cured (dried). The partition wall 3 is formed by photo-patterning the photosensitive polyimide 43 which is
2 and an outer peripheral portion 44, and the pressure chamber 33 and the ink storage chamber 35 are provided. Furthermore, this ink storage chamber 3
The ink supply hole 36 is formed in the substrate 26 through the ink supply hole 5 by laser processing. For example, the shape of the pressure chamber 33 formed as described above is a 70 x 70 (μm) square centered on the heating resistor 31, and the width of the partition wall 32 is 30 (μm). .

Here, the pressure chamber layer 2 is formed on the substrate 26 as described above.
7 is called a first plate 45, and a plate formed of the supply channel layer 28 and the orifice plate 29 and integrally joined to the first plate 45 is called a second plate 46. shall be called.

Therefore, the structure of this second plate 46 will be explained below. First, as illustrated in FIG. 20(C), a mask 48 with a predetermined pattern is attached to a jig substrate 47 such as an SUS substrate, and Ni is electroformed to a thickness of 40 (μm). The orifice plate 29 having the orifice 3o whose tip end is narrower than the distal end and whose minimum diameter is about 50 (μm) is formed by taking advantage of the fact that the mask 48 is raised around the mask 48. This is peeled off from the jig substrate 47 and the mask 48 is removed.
After removing it, Au plating (not shown) to a thickness of 0.1 (μm) is performed to fix it on the jig substrate 47 again.

Therefore, as illustrated in FIG. 20(d), uncured photosensitive polyimide 49 is coated on the orifice plate 29 to a thickness of 10 (μm), and as illustrated in FIG. 20(e), This is processed in the same manner as the pressure chamber layer 27 described above to form the ink supply path 34 centered on the orifice 30. The second plate 46 is formed by removing the orifice plate 29 on which the supply channel layer 28 is integrally formed from the jig substrate 47 and cutting it into a predetermined shape.

Then, as illustrated in FIGS. 20(f) and (g), the second plate 45.4 manufactured as described above is
An adhesive (not shown) is applied to the outer peripheral portion 44 of at least one of the orifices 30 and the heating resistor 31.
The inkjet printer head 25 is manufactured by press-bonding each other with the same details.

In this configuration, the inkjet printer head 25 has a drive circuit (not shown) connected to each electrode 39, 40, and an ink tank (both not shown) connected to the ink supply hole 36 through a communication pipe or the like. , as illustrated in FIG. 15, are arranged to face the printing paper 50 that moves relatively in the sub-scanning direction. Therefore, this inkjet printer head 25
When power is applied from each electrode 39, 40 and the heating resistor 31 generates heat, the ink 51 in contact with it evaporates and bubbles 52 are generated. At this time, the propagation direction of the pressure change in the ink 51 due to the generation of the bubbles 52 is the pressure chamber 3
3 and heads toward the orifice 30. Therefore, the power supply from the electrodes 39 and 40 is stopped in synchronization with the timing at which the ink 51 is ejected from the orifice 30, the temperature of the heating resistor 31 decreases, and the bubbles 52 contract.

Then, due to the pressure change of the ink 51 caused by the contraction of the air bubbles 52, the ink 51 that had protruded from the orifice 3o
A part of the ink droplet 5La is cut off and flies as an ink droplet 5La. Therefore, by selectively driving the heating resistor 31 to generate heat and causing the ink droplets 51a to fly from a predetermined orifice 30, an image can be formed on the surface of the printing paper 50 that moves relatively in the sub-scanning direction. In addition, in each pressure chamber 33.

The ink 51 that is sequentially replenished from the ink supply hole 36 is supplied from the ink storage chamber 35 via the ink supply path 34.

In this inkjet printer head 25,
The shapes of the ink supply path 34 and the pressure chamber 33 and the heating resistor 3
1 is symmetrical with respect to the axis of the orifice 30, the direction of action and feel of the pressure change in this part is symmetrical, and the ink droplet 51a is symmetrical with respect to the axis of the orifice 30.
It will fly in the direction of the axis.

Moreover, with this inkjet printer head 25,
Since the heating resistor 31 on the substrate 26 is surrounded by the partition wall 32 and faces the orifice 30, the pressure generated on the surface of the heating resistor 31 is deflected toward the orifice 30 without flowing to the side. As a result, the drive efficiency of the device is good, and it is possible to save labor on the equipment.

Problems to be Solved by the Invention In the inkjet printer head 25 described above, the arrangement of each part is symmetrical with respect to the fine details of the orifice 30, so the ejection direction of the ink droplets 51a is not bent. Being surrounded, the pressure generated by the bubble 52 is better deflected towards the orifice 30.

However, when the pressure directed toward the orifice 30 in this manner actually exceeds the upper end of the partition wall 32, a portion thereof actually diffuses laterally and flows out from the ink supply path 34. For this reason, the inkjet printer head 25 as described above
There is a need for proposals to reduce pressure loss and improve drive efficiency.

Means for Solving the Problems A pressure generating means is provided in a pressure chamber in which an orifice is located on the front side and an ink supply path is communicated with the pressure chamber, and at least a pressure generating means and a partition forming the pressure chamber are formed. In an inkjet printer head in which a plate is joined to a second plate in which at least an orifice is formed, a partition wall that surrounds the pressure generating means from the entire circumference to form a pressure chamber is formed, and the pressure chamber and the orifice are substantially communicated with each other. A pressure transmitting wall was formed on the partition wall, in which an ink supply channel was formed symmetrically with respect to the axis of the orifice.

An inner surface that substantially communicates between the pressure chamber and the orifice is formed on the partition wall that surrounds the working pressure generating means from the entire circumference to form a pressure chamber, and an ink supply path that is wider from the inside to the outside is formed. By forming the pressure transmission wall, the pressure generated in the pressure chamber and deflected toward the orifice by the partition wall is transmitted to the orifice without spreading laterally along the inner surface of the pressure transmission wall. Therefore, the ink droplets are ejected well, and the pressure loss due to the ink supply path of the pressure transmission wall is small because the shape of the ink supply path has fluid characteristics that make it difficult for ink to flow out.
An ink supply path with such characteristics has fluid characteristics that allow ink to easily flow from the outside into the inside, so the ink is supplied to the pressure chamber well without hindering the responsiveness of the device. There's nothing wrong with that.

Embodiment An embodiment of the present invention will be explained based on FIGS. 1 to 7. First, the inkjet printer head 5 of this embodiment
3, as illustrated in FIG. 1, a pressure transmission wall 55 is formed on the partition wall 54 of the pressure chamber 33 formed to have a thick wall so as to communicate the pressure chamber 33 and the orifice 30. .

Here, the lower pressure chamber layer 56 and the upper pressure chamber layer 57 that form the partition wall 54 and the pressure transmission wall 55 are each made of photosensitive polyimide and have a layer thickness of about 5 to 15 (μm). The pressure chamber 33 is formed in a square shape with a side of about 70 (μm), the partition wall 54 has a wall thickness of about 100 (μm), and the pressure transmission wall 55 has a wall thickness of about 30 (μm).

As illustrated in FIGS. 2 and 3, this pressure transmission wall 55 has inner surfaces 58 at its four corners that are continuous with the square pressure chamber 33, and ink supply channels 59 on its four sides.
is formed, and this ink supply path 59 connects to the pressure chamber 33.
．． The ink storage chamber 35 side is formed in a shape that is wider than the side of the ink storage chamber 35, and has fluid characteristics such that ink easily flows in and is difficult to flow out.

In this inkjet printer head 53 as well, the shape and arrangement of each part 58, 59 of the pressure transmission wall 55 are symmetrical with respect to the details of the orifice.

In this configuration, in this inkjet printer head 53, the pressure generated on the surface of the heating resistor 31 and deflected toward the orifice 30 by the partition wall 54 is transferred laterally along the inner surface 58 of the pressure transmission wall 55. Since the ink droplets 51a are well transmitted to the orifice 30 without being diffused, the ink droplets 51a are ejected from the orifice 30 with high efficiency.

Here, an ink supply path 59 is formed in the pressure transmission wall 55 that transmits the pressure inside the pressure chamber 33 to the orifice 30, but this has a fluid characteristic that makes it difficult for ink to flow out due to its shape. Ink 51 heading towards orifice 3o
The pressure loss is minute. The ink supply path 59 of the pressure transmission wall 55 having such characteristics has fluid characteristics that allow the ink 51 to easily flow into the inside from the outside, so that the ink 51 is well supplied to the pressure chamber 33. This does not affect the responsiveness of the device.

In other words, in this inkjet printer head 53,
Ink supply path 5 through which ink 51 easily flows in and is difficult to flow out
Since the pressure chamber 33 and the orifice 30 are communicated with each other through the pressure transmission wall 55 formed with a
It is possible to achieve both the efficiency of transmitting the pressure to zero and the efficiency of supplying the ink 51 to the pressure chamber 33, contributing to labor saving and improved performance of the apparatus.

In this inkjet printer head 53, the orifice plate 29 and the substrate 26 are connected by the partition wall 54 of the pressure chamber 33 and the pressure transmission wall 55, so that the entire device has high rigidity and good durability. Moreover, in this inkjet printer head 53, since the partition wall 54 of the pressure chamber 33 located on the same plane as the heating resistor 31 has a thick wall thickness, the pressure generated on the surface of the heating resistor 31 causes the partition wall 54 to
4 is also prevented from being destroyed.

Further, in the inkjet printer head 53 of this embodiment, the pressure transmission wall 55 is bonded to the back surface of the orifice plate 29, but the present invention is not limited to the above structure, and as shown in FIG. As illustrated, an inkjet printer head 60 in which a gap exists between these members 29,55 is also possible. In this inkjet printer bed 60, as shown in the figure, the shape of the orifice 62 formed in the orifice plate 61 is narrow at the tip and widened at the end, so that the pressure generated within the pressure chamber 33 is reduced. Even beyond the upper end of the pressure transmission wall 55,
It is designed to be well transmitted into the orifice 62 without spreading to the sides. Here, the orifice plate 61 provided with the orifice 62 having the above-described shape is a jig substrate (not shown) in which a protrusion is formed by isotropic etching.
The fact that it can be easily formed by using, etc. is disclosed in a patent application filed by Ganto Honro on May 16, 1990 titled "Method for Manufacturing an Inkjet Printer Head."

Furthermore, the inkjet printer head 53 of this embodiment
In the above, an example in which the partition walls 54 forming the pressure chambers 33 are individually divided is illustrated, but as illustrated in FIGS. 6 and 7, an inkjet in which the partition walls 63 are formed as a single layer without being divided into each pressure chamber 33 is shown. A printer head 64 or the like may also be implemented. In this case, since the step of dividing the partition wall 63 is omitted, the productivity of the apparatus can be improved.

In addition, the above-mentioned inkjet printer head 53.60
．． In No. 64, a bubble jet method using the heating resistor 31 as a pressure generating means was exemplified, but the present invention is not limited to the above method, and may also be an on-demand method using an electrostrictive element as a pressure generating means. It is also applicable to

Effects of the Invention As described above, the present invention has a structure in which a pressure generating means is provided in a pressure chamber in which an orifice is located on the front surface and an ink supply path is communicated with the pressure chamber, and at least the pressure generating means and the partition wall forming the pressure chamber are formed. In an inkjet printer head in which a first plate is joined to a second plate in which at least an orifice is formed, a partition wall that surrounds the pressure generating means from the entire circumference to form a pressure chamber is formed, and the pressure chamber and the orifice are connected to each other. An ink supply path that is expanded from the inside to the outside is formed on the partition wall, and the pressure transmission wall is formed on the partition wall to form an ink supply path that is narrower than the inside. The pressure deflected toward the orifice by the partition wall is transmitted to the orifice without being diffused laterally along the inner surface of the pressure transmission wall, resulting in good ejection of ink droplets. The pressure loss caused by the ink supply path is minimal because the shape of the ink supply path has fluid characteristics that make it difficult for ink to flow out, so it is possible to improve the drive efficiency of the device and save labor. Furthermore, the shape of the ink supply path with the characteristics described above has a fluid characteristic that allows ink to easily flow into the inside from the outside, so ink is supplied to the pressure chamber well and the responsiveness of the device is improved. This has the advantage that it is possible to obtain an inkjet printer head with a simple structure and good drive efficiency and responsiveness without hindering the above.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional side view showing an embodiment of the present invention, Fig. 2 is a perspective view of the main parts, Fig. 3 is a plan view, Fig. 4 is a plan view with each part disassembled, and Fig. 5 is the first Vertical side view showing a modified example, No. 6
The figure is a longitudinal side view showing the second modification, Fig. 7 is an exploded plan view of each part, Fig. 8 is a front view showing the first conventional example, Fig. 9 is a longitudinal side view, and Fig. 10 is a front view showing the first conventional example. 11 is an exploded perspective view of the second conventional example; FIG. 12 is a longitudinal side view of the third conventional example; and FIG. 13 is an exploded perspective view of the fourth conventional example. Figure 14 is a perspective view showing the fifth conventional example;
Figure 5 is a longitudinal cross-sectional side view of an inkjet printer head filed by the present applicant as Japanese Patent Application No. 2-58881, No. 16.
The figures are an exploded plan view of each part, Fig. 17 is an exploded perspective view, Fig. 18 is a perspective view, Fig. 19 is a vertical side view of the main parts, and Fig. 20 is an exploded perspective view.
The figure is a manufacturing process diagram. 30.62... Orifice, 33... Pressure chamber, 53, 60° printer head, 54, 6 Force transmission wall, 58... Inner surface, 5 31... Pressure generating means, 64... Infusiera 3 ...Partition wall, 55...Pressure 9...Ink supply route Tokyo Electric Co., Ltd. Figure A (a) (b) (C) (cl) (a) Figure 7 (b) (C) (d) 3''6 Figures (a) (b')

Claims (1)

[Claims] A structure in which a pressure generating means is provided in a pressure chamber having an orifice located on the front surface and communicating with an ink supply path, and a first plate in which at least the pressure generating means and a partition wall forming the pressure chamber are formed; In an inkjet printer head joined to a second plate in which an orifice is formed, a partition wall that surrounds the pressure generating means from the entire circumference to form a pressure chamber is formed, and the pressure chamber and the orifice are substantially communicated with each other. An inkjet printer head characterized in that a pressure transmission wall is formed on the partition wall, the pressure transmission wall having an inner surface and an ink supply path that is expanded from the inner side to the outer side and is formed symmetrically with respect to the axis of the orifice.