JPH0820108A - Inkjet head and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To provide an ink jet head with efficient discharge characteristic by employing a buckling body. CONSTITUTION:An ink supply port 102 is provided to a substrate 101. A buckling body, fixed at its both ends to the substrate 101 and capable of deforming in buckling deformation, is heated with a heater layer 109 provided thereto, and moves inside the ink supply port 102 in the direction vertical to the substrate 101. Ink is discharged by movement of a piston 103 that is in a size approximately the same as the ink supply port 102 and moves in the direction vertical to the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head of a so-called ink jet head printer, in which liquid ink is ejected in the form of minute liquid droplets and ejected onto the paper surface for printing.

[0002]

2. Description of the Related Art With the development of a computer, the existence of a printer as an output device of the information has become important recently. In other words, code information, image information, etc. from the computer are printed on paper or O
A printer for printing and printing on a film for HP (overhead projector) is required to have higher performance, smaller size, and higher functionality as the computer becomes smaller and higher performance. Among them, inkjet printers that eject liquid ink onto paper, polymer film, etc. to form character information and images have the features of downsizing, high performance, and low power consumption, and have been actively developed in recent years. Has been done to.

The most important part of the structure of an ink jet printer is a part called an ink jet head for ejecting ink, and the key is how to make this head small and at low cost.

Several types of ink jet heads have been conventionally used. One uses a piezoelectric element, and FIGS. 13 (a) and 13 (b) show
3A and 3B are schematic cross-sectional views when a piezoelectric element is energized and when energization is stopped. The piezoelectric element 11 is provided inside the container 10.
Is provided, an ink pressure chamber is formed between the piezoelectric element 11 and the inner wall of the container 10, an ink inflow hole 12 is provided on one side of the container 10, and a nozzle 13 is provided on the other side. A high voltage is applied to the piezoelectric element 11 to cause mechanical deformation of the piezoelectric element 11, and a pressure is generated in the ink pressure chamber by using this mechanical displacement, whereby ink is ejected in a granular form from the nozzle. It is a thing.

A bubble jet method is another method. FIG. 14 is an exploded perspective view of an example thereof. A heater 23 is provided inside a cavity between a lid 20 and a substrate 21 in which grooves that form a plurality of nozzles 22 are formed.
The cavity is full of ink. This heater 2
The ink is boiled by rapidly heating 3 to form bubbles, and the ink is ejected from the nozzle due to the pressure change due to the generation of the bubbles.

[0006] Also, Japanese Patent Laid-Open Publication No. 30543 of 1990.
There is also a buckling system in which a bimetal element is provided in the ink chamber, the bimetal element is heated and deformed, and the ink is pressurized and ejected by this deformation, as shown in FIG.

Further, there is a system in which a buckling structure (hereinafter referred to as a buckling body) is used in place of the bimetal element, and its deformation causes the ink to be pressurized and ejected. Japanese Patent Application No. 5-278271, Japanese Patent Application No. 6-55525, filed by the applicant.
Japanese Patent Application No. 6-96670 and the like.

[0008]

First, in the method using the first piezoelectric element, a piezoelectric material is formed into multiple layers to form a piezoelectric element, which is mechanically processed to form a head. Since it is necessary to mechanically process when forming the ink, there is a drawback that the distance between the ink chambers cannot be reduced so much, and as a result, the distance between the nozzles that eject ink cannot be reduced. In addition, a high voltage is required to deform the piezoelectric element.

In the case of the second bubble jet method, since it is necessary to boil the ink to form bubbles, it is necessary to instantaneously raise the temperature of the heater to several hundreds of degrees Celsius, and the deterioration of the heater cannot be avoided. However, it had a short life.

The third buckling method has a drawback that the structure becomes complicated because it is necessary to form a bimetal structure in which different kinds of materials are laminated as a driving source. Further, when a drive source is created, it is required to create a large number of minute drive sources all at once. However, in the method of the above-mentioned Japanese Patent Laid-Open Publication, it is necessary to individually create and assemble the parts, and the integrated Was difficult to convert. Further, there is a problem in the shape of the ink supply hole and the buckling member, and the efficiency of ink supply is poor.

The use of the buckling body eliminates the drawbacks of the conventional buckling method, but further improvement of ejection characteristics is desired.

[0012]

In order to solve the above-mentioned problems, the following means are used in the present invention.

A supply hole for supplying ink onto the substrate, a buckling member having both ends fixed on the substrate to cause buckling deformation, and a buckling member attached to the buckling member via an insulating layer to heat the buckling member. A heater and a piston portion that reciprocates along the wall surface inside the ink supply hole and is configured integrally with the buckling body are provided, and ink is ejected by the movement of the piston portion in a direction perpendicular to the substrate.

When the orifice plate is bonded to one surface of the buckling body via the bonding layer, the heights of the bonding surfaces of the bonding layer and the buckling body are made substantially equal.

The material of the substrate is single crystal silicon, and the wall surface of the ink supply hole is constituted by the (111) plane.

The piston part is formed of a shell structure together with the buckling body. Forming a recess corresponding to the ink supply hole on the substrate; forming a sacrificial layer inside the recess and on the lower portion of the buckling body formed on the upper surface of the substrate; The manufacturing method includes a step of forming a piston portion and a step of forming an ink supply hole and removing a sacrifice layer thereafter.

In the above manufacturing method, a silicon single crystal is used for the substrate, and recesses are formed by silicon anisotropic etching.

In the above manufacturing method, the sacrificial layer formed under the buckling body is formed of an aluminum thin film.

In the above manufacturing method, the piston portion and the buckling body are simultaneously formed by plating.

[0020]

In the present invention, since the buckling phenomenon of the buckling body is used for ejecting ink, the structure of the driving body is simple as compared with the case of using a bimetal or a piezoelectric element. In addition, if the size of the piston is set to an appropriate size, an integrated head with high resolution and small size can be constructed. Further, when the gap between the piston and the wall surface around the piston is appropriately set, the backflow of ink can be prevented, and efficient ejection can be performed. If the gap is provided perpendicularly to the substrate, the size of the gap does not change even when the piston is driven, the characteristics do not change easily, and the length of the gap in the substrate direction, that is, the thickness of the piston increases The backflow resistance (flow path resistance) can be easily increased, and the effect of preventing ink backflow can be increased.

Further, if the heater circuit is separately formed, the resistance value can be made higher than that when a current is directly applied to the buckling body, and the power consumption can be made smaller when the same power is applied. Further, when the heater is formed on the gap formed by the sacrificial layer, the heater layer floats from the substrate, so that the amount of heat that escapes to the substrate during heating is small and power consumption can be reduced.

By patterning the adhesive layer in the shape of a cavity, the cavity can be easily formed. Further, at this time, since the isolation can be made completely so that the ink does not flow between the adjacent cavities, there is no pressure loss at the time of ink ejection, and the efficiency can be improved.

When the (111) plane is used for the wall surface of the supply hole of the substrate, the anisotropic etching rate is slow, and this surface remains until the end, and the dimensions of the supply hole and the gap are accurate.

At this time, the crystal plane orientation of the substrate is (1
When the substrate having the (00) orientation is used, the supply hole can be formed perpendicularly to the substrate, the size of the gap does not change even if the piston moves, and the characteristics do not change. Further, it has a great effect of preventing backflow of ink. Further, when a substrate having a crystal plane orientation of (110) is used, this substrate is mainly used for manufacturing a semiconductor and is consumed in a large amount, so that there is an advantage that it can be inexpensive, and cost can be reduced. Become.

Since the piston having a shell structure which is provided in the central portion of the buckling body and is integral with the buckling body has a concave shape, it has a high bending rigidity and is unlikely to be deformed, so that a strong structure can be configured. Further, since it is configured by the shell structure, even if the volume is increased, the weight of the moving part is small and it is possible to drive at high speed.

Further, the buckling member, the piston and the wiring portion can be plated at the same thickness at one time. By doing this, it is not necessary to provide a thick part in a part,
The entire thickness can be made uniform. When plating is performed, if the film thickness of each portion is different, internal stress is often generated inside the film, residual stress may occur after the film is formed, or the film may be peeled off due to the residual stress. If plating can be performed to a uniform thickness, such problems will be solved, it is possible to suppress the generation of internal stress, it is possible to avoid deformation due to stress after creation, and it is possible to create precise structures. .

Since the concave portion is formed in the substrate and the piston portion is formed therein and the concave portion can be used as it is for the ink supply portion, the shape of the piston portion can be accurately formed. Moreover, since the buckling body and the piston portion are formed after forming the sacrificial layer in the recess, the size of the gap can be controlled by the thickness of the sacrificial layer.
Very small gaps can be easily formed.

When a silicon single crystal is used for the substrate and a process for leaving the (111) plane on the wall surface of the supply hole is used,
Due to the slow rate of anisotropic etching, this surface remains to the end and the feed hole and gap dimensions are accurate.

At this time, if a process using a substrate having a (100) orientation is used, a supply hole can be formed perpendicularly to the substrate, the size of the gap does not change even if the piston moves, and the characteristics change. Absent. It also prevents the backflow of ink. In addition, when a process using a substrate having a crystal plane orientation of (110) is used, the substrate is consumed in large quantities for the production of a semiconductor, so that there is an advantage that the substrate can be obtained at low cost and cost can be reduced.

When aluminum is used as the sacrificial layer, vapor deposition and sputtering can be used to form the sacrificial layer, a thin sacrificial layer can be easily formed, and etching can be easily performed, so that a fine pattern can be easily formed. is there.
Further, in the case of aluminum, when etching is performed, there is a characteristic that a residue does not remain even in the thin gap and etching can be easily performed, and since a thin sacrifice layer can be formed, backflow of ink is prevented.

When aluminum is used for the sacrificial layer, the etching of aluminum simultaneously proceeds with anisotropic etching, and the sacrificial layer is removed at the same time, so that the process can be simplified.

When the piston is formed by plating, the piston can be easily formed in the recess. Further, particularly in the case of plating, Ni, Cu, Co or the like can be used as a material, but these are easy to plate and it is easy to form a film having low internal stress. Further, these metals have a relatively large coefficient of thermal expansion and Young's modulus, and it is possible to increase the strain energy stored in the buckling body. It is also easy to make these alloys, and in this case, it is possible to increase the strength of the buckling body to prolong its life and increase the strain energy. Further, by using plating, it is possible to form the piston portion with a shell structure having a recess and having an equal thickness.

[0033]

FIG. 1 is a sectional view of an embodiment of the present invention. Ink supply holes 102 are provided perpendicularly to the surface of a silicon single crystal substrate 101. Inside the ink supply hole 102, a piston 103 movable along the wall surface 104 in the direction perpendicular to the substrate 101 is provided. Piston 10
3 and the wall surface 104 of the ink supply hole 102
Is set in the range of approximately 0.05 to 5 μm. The piston 103 is integrally fixed to and supported by the buckling body 106.

Both ends of the buckling member 106 are fixed portions 1 respectively.
Although it is fixed to the substrate 101 at 07 and 107, the other portions are not fixed, and a gap 10 is formed from the substrate 101.
It is in a floating state, keeping 8. The heater layer 1 is formed on the back surface of the end portion of the buckling body 106 via the upper insulating layer 110.
09 is provided. The back surface of the heater layer 109 is sandwiched between the lower insulating layers 111, and serves to electrically insulate the buckling body 106 and to prevent oxidation / deterioration and corrosion during heating. An oxide film 112 made of SiO ₂ is provided on both surfaces of the substrate 101. In the figure, the lower insulating layer 111 is provided over the entire length of the buckling body 106, but it is not particularly necessary to provide it over the entire length, and it is sufficient to cover the heater layer 109.

An electric signal is supplied to the heater layer 109 by the wiring layer 113 to perform heating. Although it is possible to heat the buckling body 106 by energizing it, providing a heater layer is more convenient for heating.

An adhesive layer 114 is provided on the fixed portions 107 at both ends of the buckling body 106 and on the periphery thereof, and an orifice plate 115 is adhered thereon. The space surrounded by the adhesive layer 114 becomes a cavity 117 that contains ink.
Nozzles 116 are provided on the orifice plate 115, from which ink is ejected. Next, the operation of the device shown in FIG. 1 will be described.

During operation of this element, ink is supplied from the ink supply hole 102 to the cavity 117 surrounded by the adhesive layer 114, and the cavity 117, the gaps 108, 1
05, the ink supply holes 102 are all filled with ink.

Then, a current is supplied to the heater layer 109 in a pulsed form from an external power source (not shown) to rapidly heat it. Then, the buckling body 106 that is in contact with it is also rapidly heated and causes thermal expansion. However, since both ends of the buckling body 106 are fixed to the substrate 101 by the fixing portions 107, thermal expansion causes compressive stress inside the buckling body 106. When this compressive stress exceeds a certain limit, the buckling body 1
No. 06 deforms rapidly (buckles) and deforms in the vertical direction of the substrate 101 as shown by the dotted line in FIG. Then
Piston 103 integrally configured with buckling body 106
Also moves to the position indicated by the dotted line.

At this time, in the cavity 117, the movement of the piston 103 causes the shaded portion 118 in FIG.
Volume change occurs. This volume change is caused by the heater 10
Since the buckling body 106 can be deformed rapidly by heating 9 rapidly, it can be rapidly generated. Therefore, the pressure is rapidly increased in the cavity 117, and the ink can be ejected from the nozzle 116.

When the current pulse to the heater layer 109 stops flowing, the buckling body 106 is cooled, returns to its original state and is not deformed. At this time, an amount of ink corresponding to the ejected ink is supplied from the ink supply hole 102 through the gap 105 into the cavity 117, so that the ink can be ejected by applying a current pulse to the heater layer 109 again. It will be possible.

9A and 9B show the operation of the piston in more detail.
It is sectional drawing which shows the state before and after the deformation | transformation of 06.
The buckling body 106 is thermally expanded by heating, and buckling deformation occurs as shown in FIG. 9B. As a result, the piston 103 is driven in the direction perpendicular to the substrate 101. Ink ejection is shown in FIGS. 12 (a) and 12 (b). (A) is a state before the buckling body is deformed, and (b) is a state after the buckling body is deformed. Due to the deformation of the buckling body 106, the piston 103 is driven perpendicularly to the substrate 101 to increase the pressure in the cavity 117 and eject ink droplets.

Here, the following points are important for efficient ink ejection. When the ink is ejected by the movement of the piston 103, the volume change 118 needs to be set to 2 to 3 times or more the volume of the ejected ink particles. Therefore, the piston 103 should be large. However, if it is too large, the size of the entire head becomes large, and therefore an appropriate size must be selected. Generally, the printer resolution is 300-600.
dpi (dot per inch) is required. If the nozzles are lined up at this interval, an integrally configured head can be created. Therefore, the lateral width of the head is preferably 80 to 40 μm or less. Therefore, if the length of the piston 103 is 300 to 600 μm and the diameter of the ink droplet is about 40 μm, a minimum displacement of 5 to 6 μm is required. On the other hand, if the length of the portion of the buckling body 106 to be heated (the length on one side excluding the piston 103) is 300 μm, the deformation of 5 to 20 μm is possible depending on the thickness and the rising temperature. Can be discharged.

Particularly, the length of the piston 103 is set to 300 μm.
When m, the width is 50 μm, and the thickness is about 50 μm, an integrated head with high resolution and small size can be configured.

When the piston 103 moves to eject ink, the ink in the cavity 117 is pressurized and ejected from the nozzle 116, but at the same time, flows backward through the gap 105 toward the supply hole 102 side. Therefore, the gap 1
05 is preferably as small as possible. However, if it is made too small, the driving of the piston 103 will end,
When returning to the original position, the supply of ink to the cavity 117 cannot catch up, and air is sucked into the cavity 117 from the nozzle 116, which causes malfunction, so it is important to select an appropriate gap.

The gap 105 is provided in the direction perpendicular to the substrate as shown in the embodiment, and when the size thereof is set to 5 μm or less, particularly preferably 1 to 0.05 μm, the backflow of ink can be prevented and the efficiency is improved. Discharge is possible. When the gap 105 is provided perpendicularly to the substrate, the size of the gap 105 does not change even when the piston 103 is driven, and the characteristics are hard to change.

Further, when the gap 105 is provided perpendicularly to the substrate, the length of the gap 105 in the direction perpendicular to the substrate 101, that is, the thickness of the piston 103 is increased.
The backflow resistance of ink (flow path resistance) can be easily increased, and the effect of preventing backflow of ink can be increased. The thickness of the piston 103 is preferably larger than the moving distance of the piston, and is at least 5 μm, preferably 20 μm or more.

2 (a) to 2 (f) are schematic cross-sectional views of respective steps for producing the element of the first embodiment described above.

First, as shown in FIG. 2A, the substrate 101
After forming an oxide film 112 on both surfaces of the above and patterning it to open a window, anisotropic etching is performed using a KOH solution. If a substrate having a crystal plane orientation of (110) is used as the substrate 101, a (111) plane having a slow etching rate remains, etching proceeds in a direction perpendicular to the substrate 101, and recesses 203- are formed on both sides. a, 203-b
Since the gap is formed, the gap 105 for preventing the backflow of the ink described in FIG. 1 can be accurately formed. Recess 203-a,
The remaining portion 212 sandwiched by 203-b serves as a base for forming the piston.

Next, as shown in FIG. 2B, the sacrificial layer 20.
4 is formed. The sacrificial layer 204 is finally removed by etching to form the gaps 105 and 108 in FIG. 1, and the material can be aluminum, silicon dioxide, photoresist, or polyimide resin. As a method of forming aluminum and silicon dioxide as a sacrificial layer, a method such as vapor deposition, sputtering, CVD or the like can be used. Next, the piston 103 is created by plating the upper recess 203-a with a metal.
This is because a conductive layer (for example, Ni, Ta, Ag) as a base is formed in a thickness of 0.01 to 1 μm on the entire surface before plating, and a portion which is not desired to be plated is covered with a photoresist to form a portion. It can be achieved by plating. In this case, it is effective to rotate the substrate 101 or perform film formation from an oblique direction when forming the conductive layer so that the conductive layer is not broken by the corner portion 217 of the recess 203-a. Further, it is also particularly effective to adopt a film forming method such as CVD capable of excellently covering the step. The piston 103 is formed to have substantially the same height as the upper surface of the substrate 101. Piston 10
As the material constituting 3, Ni, Cu, Co, P, S
Alternatively, alloys thereof can be used.

When aluminum is used as the sacrificial layer 204, vapor deposition and sputtering can be used to form the sacrificial layer, a thin sacrificial layer can be easily formed, and etching can be easily performed, so that a fine pattern can be obtained. Is easy to form. Further, in the case of aluminum, when etching is performed, there is a characteristic that a residue can be easily left inside the thin gap, and a thin sacrificial layer can be formed. Therefore, the gap is made small and backflow of ink is prevented.

Further, when Ni is used as the material of the piston 103, it is possible to easily form a film having a low internal stress by plating easily.

Next, as shown in FIG. 2C, a lower insulating layer 111, a heater layer 109 and an upper insulating layer 110 are sequentially formed.

Materials for the upper and lower insulating layers 110 and 111 include oxides such as SiO ₂ and Al ₂ O ₃ and Si.
Nitride such as N, AlN, TaN and MoN, and carbide such as SiC can be used.

The material of the heater layer 109 is Ni, Co, C
r, Hf, Mo, Ta or alloys thereof can be used. The heater layer 109 can be formed in a zigzag shape or a sawtooth shape so as to have a long length, which has the effect of increasing the resistance value and reducing the current consumption.

When the heater layer 109 is formed on the sacrificial layer 204, the heater layer 109 is formed on the substrate 10 as shown in FIG.
Since it is in a state of being floated from 1, the amount of heat that escapes to the substrate 101 during heating is small, and power consumption can be reduced.

Next, as shown in FIG. 2D, the buckling member 10
6 and the wiring pattern 210 are formed by plating.
The plating method can be performed by forming a pattern with a photoresist on a portion 211 that does not require plating, and removing the resist after plating. The wiring pattern 210 is formed in a pattern that connects the wiring to the heater layer 109. The materials for forming the buckling body 106 include Ni, Cu, Co,
P, S or alloys thereof can be used.

In particular, Ni, Cu, and Co have a relatively large thermal expansion coefficient and Young's modulus, so that the strain energy stored in the buckling body can be increased and a large ejection energy can be obtained. Further, when these alloys are used, the strength of the buckling body 106 is improved, the life is extended, and the Young's modulus is increased to increase the strain energy and increase the ejection energy.

Next, as shown in FIG. 2E, the entire substrate 101 which has been subjected to the above processing is immersed in a KOH solution and anisotropically etched to remove the remaining portion 212. At this time, if aluminum is used for the sacrificial layer 204, the etching of aluminum proceeds simultaneously with the anisotropic etching, and the sacrificial layer 204 is removed at the same time, so that the process can be simplified.

Next, as shown in FIG. 2F, an orifice plate 115 having a nozzle 116 is adhered to the upper part of the substrate 101 by an adhesive layer 114. As the adhesive layer 114, an ultraviolet curable adhesive or a thermosetting adhesive can be used.

FIG. 3 is a plan view of the pattern of the adhesive layer 114 and its periphery. The adhesive layer 114 is formed in a shape like a diagonal line, and thus the cavity 117 is formed.
The heater layer 109 passes under the fixing portion 107 of the buckling body 106 and is connected to the heater layer formed under the buckling body 106. The heater layer 109 is connected to the wiring layer 113. The buckling body 106 is formed, for example, by forming gaps 301, 301 in a nickel plating layer.

Here, the adhesive layer 114 is formed in FIG.
The height of the surface 216 in (f) is set to be substantially equal over the entire substrate. Although only a portion of the heater layer 109 that passes through the fixing portion 107 is raised, it is possible to configure the heater layer 109 and the upper and lower insulating layers 110 and 111 to be substantially negligible if they are thin.
In the case of the first embodiment, the height of the cavity 117 needs to be 10 to 50 μm, so the thickness of the adhesive layer 114 is set to this thickness. On the other hand, the thickness of each of the heater layer 109 and the upper and lower insulating layers 110 and 111 is 0.1 to 1
It is formed to a thickness of about μm. In the case of the present invention, the thinner the heater layer, the better the heat conduction to the buckling body, and the more efficient heating becomes possible. Moreover, since the heater layer and the upper and lower insulating layers are formed by a thin film process, it is possible to form them with the above-mentioned thickness. Then, the surface 216
The heights can be configured to be substantially the same height. In this way, when the adhesive layer 114 is patterned into cavities as shown in FIG. 3, the isolation can be easily completed so that ink does not flow between the adjacent cavities. If there is a step, a gap is created in that portion, and a pressure loss occurs when ink is ejected, making ejection impossible. Therefore, in this case, there is no pressure loss when ejecting ink, and the efficiency can be improved.

FIG. 4 is a schematic sectional view of the second embodiment of the present invention. Ink supply holes 402 having obliquely upper and lower slopes 404-a and 404-b are provided on the substrate surface of a silicon single crystal substrate 101. Inside the supply hole 402, there is provided a piston 403 having a trapezoidal cross section, which has a cross section substantially equal to the wall surface 404-a at the upper part of the supply hole 402 and is movable in the direction perpendicular to the substrate 101. The gap 405 between the piston 403 and the wall surface 404-a above the ink supply hole 402 is
It is set in the range of approximately 0.05 to 5 μm. The piston 403 is integrally fixed to and supported by the buckling body 106.
Both ends of the buckling body 106 are fixed to the silicon substrate 101, but the other portions are not fixed to the substrate 1.
From 01, it is in a state of floating with a gap 408 being maintained. A heater layer 109 is provided on the back surface of the buckling body 106, and one heater layer 109 is provided on each of the left and right sides in the example of FIG. Heater layer 109
Is sandwiched between the upper insulating layer 110 and the lower insulating layer 111,
It plays a role of electrically insulating the buckling body 106 and preventing oxidation / deterioration and corrosion during heating. An oxide film 112 is provided on each side of the silicon substrate 101.

An electric signal is supplied to the heater layer 109 by the wiring layer 113 to heat it. An adhesive layer 114 is provided on the fixing portion 107 of the buckling body 106 and on the periphery thereof,
An orifice plate 115 is adhered on it. Nozzles 116 are provided on the orifice plate 115, from which ink is ejected.

The second embodiment is structurally different from the first embodiment except that the wall surfaces 404-a and 404-b of the ink supply hole 404 are not perpendicular to the substrate 101 and have an angle. And has the same structural advantages. However, the gap 405 changes when the piston 403 reciprocates. Here, the ink supply hole 402 is formed by the oxide film 112.
After the patterning is performed to open the window, anisotropic etching is performed using a KOH solution. At this time, when a silicon single crystal having a crystal plane orientation of (100) is used for the substrate 101, a (111) plane having a slow etching rate remains, and a wall surface 404-a in a direction of 55 ° with respect to the substrate 101,
404-b is formed.

A substrate having a crystal plane orientation of (100) is mainly used for producing a semiconductor and is consumed in a large amount, so that it has an advantage that it can be obtained at a low cost and the cost can be reduced.

The ejection operation is exactly the same as in the first embodiment shown in FIG. 1, and the piston 403 moves in the direction perpendicular to the substrate to eject ink from the nozzle 116. FIGS. 10A and 10B show the operation of the piston in more detail, and are cross-sectional views of the buckling body 106 before and after deformation, respectively. The buckling body 106 thermally expands due to heating, and causes buckling deformation as shown in FIG. As a result, the piston 403 is
It is driven in the direction perpendicular to 1.

Here, the point that ink is ejected efficiently is also the same as in the first embodiment, and the following points are important and the same discussion can be made regarding the size of the piston 403. As a result, in particular, the length of the piston 403 is 300 μm for the long side of the trapezoidal cross section and 50 μ for the width.
When the m and the thickness are about 50 μm, a high resolution and small integrated head can be configured.

The size of the gap 405 is also the same as that of the first embodiment. In the second embodiment, the size is 5 μm or less, particularly preferably 1 although it is provided on the substrate in the plane direction of 55 °. If it is set to between 0.05 μm and 0.05 μm, backflow of ink can be prevented, and efficient ejection can be performed. Further, by increasing the length of the gap 405, that is, the thickness of the piston 403, it is possible to easily increase the backflow resistance of ink (flow path resistance) and increase the effect of preventing backflow of ink. The thickness of the piston 403 is preferably larger than the moving distance of the piston 403, and the same applies to the fact that the thickness is at least 5 μm, preferably 20 μm or more.

5 (a) to 5 (f) are schematic cross-sectional views of respective steps for forming the structure of the second embodiment. Each of these steps can be performed using the same process as each step of FIGS. 2 (a) to 2 (f). The difference is that a substrate having a (100) orientation is used as the first silicon single crystal substrate 101. Therefore, as shown in FIG.
3-a and 203-b are formed at an angle of 55 ° with respect to the substrate 101. The other processes are exactly the same, and therefore the description of each step is omitted.

The adhesion of the orifice plate 115 is also the first
The same method as in the embodiment of can be adopted. That is, the adhesive layer 1
The height of the surface 216 of FIG. 5 (f) where 14 is formed is set to be substantially equal over the entire substrate, and the adhesive layer 114 is formed as shown in FIG.
In the same way as patterning in the shape of a cavity,
To prevent ink flow between adjacent cavities,
Complete isolation and easy to create. If there is a step, a gap is created in that portion, and a loss of pressure occurs when ejecting ink, making ejection impossible. Therefore, in this case, there is no pressure loss when ejecting ink, and the efficiency can be improved.

Next, a third embodiment of the present invention will be described.
FIG. 6 (a) is a sectional view of the third embodiment of the present invention, and FIG. 6 (b) is a schematic plan view without the orifice plate. The ink supply hole 10 is perpendicular to the surface of the silicon single crystal substrate 101.
2 are provided. The wall surface 1 is inside the supply hole 102.
A piston 603 that is movable in the direction perpendicular to the substrate 101 is provided along the axis 04. The gap 105 between the piston 603 and the wall surface 104 of the ink supply hole 102 is about 0.05.
It is set in the range of ˜5 μm. The piston 603 is integrally fixed to and supported by the buckling body 606. The both ends of the buckling member 606 are fixed portions 107, and the silicon substrate 101
However, the other portions are not fixed and are in a state of floating from the substrate 101 with a gap 108 kept therebetween. The buckling body 606 and the piston 603 are integrally formed by members having approximately the same thickness. Piston 60
The buckling member 606 is provided with a recess 619.

FIG. 7 shows a buckling member 606 and a piston 60.
3 is a cross-sectional perspective view taken along the vicinity of the center line of FIG. That is,
A recess 619 is provided in the center of the buckling body 606, and a piston 603 is configured by this.

As shown in FIG. 6A, the buckling member 60
A heater layer 109 is provided on the back surface of 6, and one heater layer 109 is provided on each of the left and right sides in this example. The heater layer 109 is sandwiched between the upper insulating layer 110 and the lower insulating layer 111, and the buckling member 6 is formed.
06, it plays a role of electrical insulation and prevention of oxidation / deterioration and corrosion during heating. Silicon substrate 101
An oxide film 112 is provided on both surfaces of.

An electric signal is supplied to the heater layer 109 by the wiring layer 113 to heat the heater layer 109. An adhesive layer 114 is provided on the fixing portion 107 of the buckling body 606 and its periphery,
The orifice plate 115 is bonded. Orifice plate 11
5, a nozzle 116 is provided, from which ink is ejected.

As shown in FIG. 6 (b), the buckling body 60
6 is buckled by being separated by two gaps 601 and 601 provided in the plating layer. The recess 619 integrally formed in the center by plating is a hollow piston 60.
It becomes the inner surface of 3.

Next, the operation of the device shown in FIG. 6 will be described. During operation of this element, the ink supply hole 100 is placed in the cavity 117, which is a space surrounded by the adhesive layer 114.
The ink is supplied by the cavity 117 and the gap 10
8, 105 and the ink supply hole 102 are all filled with ink.

Then, a current is supplied to the heater layer 109 in a pulsed form from an external power source (not shown) to heat it. Then, the buckling member 606 that is in contact with it is also rapidly heated and causes thermal expansion. However, since both ends of the buckling body 606 are fixed to the substrate 101 by the fixing portions 107, thermal expansion causes a compressive stress inside the buckling body 606.
When the compressive stress exceeds a certain limit, the buckling body 606 is rapidly deformed (buckles) and is deformed in the vertical direction of the substrate 101. Then, the piston 603 integrally configured with the buckling body 606 also moves in the vertical direction.

In this case, the piston 603 at the center of the buckling member 606 has a concave shape as shown in FIG. 7, and therefore has high bending rigidity and is unlikely to be deformed. Therefore, the buckling deformation occurs only in the portion of the buckling body 606 other than the piston portion. Further, the deformation caused in the buckling body 606 is caused by the buckling body 60.
6 is deformed with the central portion 620 other than the piston portion as an antinode, and the end portion 62 of the boundary between the buckling body 606 and the piston 603 is generated.
Although there is a concern that the deformation of No. 1 will not occur, in the configuration of the present invention,
Since the energy of this deformation is greater than the energy of deformation of the fixed portion 107 of the buckling body 606 as a node and the end portion 621 as an antinode, the desired deformation occurs with the end portion 621 as an antinode.

When deformed in this way, the cavity 11
7, the movement of the piston 603 causes a volume change corresponding to the shaded portion in FIG. This volume change is caused by rapidly heating the heater 109,
Since the buckling body 606 can be deformed, it can be rapidly generated. Therefore, the pressure is rapidly increased in the cavity 117, and the ink can be ejected from the nozzle 116.

When the current pulse to the heater layer 109 stops flowing, the buckling body 606 is cooled, returns to its original state, and is not deformed. At this time, an amount of ink corresponding to the ejected ink is supplied from the ink supply hole 102 through the gap 105 into the cavity 117, so that it is possible to eject the ink by applying a current pulse to the heater layer 109 again. Become. 11A and 11B show the operation of the piston in more detail, and are cross-sectional views showing states of the buckling body before and after deformation, respectively.
The buckling body 606 is thermally expanded by heating, and buckling deformation occurs as shown in FIG. As a result, the piston 603 is driven in the direction perpendicular to the substrate 101.

In the third embodiment, since the piston 603 is composed of a three-dimensional shell having a thin structure, it is possible to form a rigid structure having high rigidity despite the thin shell. Further, since it has a shell structure, the weight of the movable part is small and it is possible to drive at high speed.

Here, consideration regarding the size of the piston, the size of the gap, and the like for efficiently ejecting the ink is the same as in the case of the first embodiment.

FIGS. 8A to 8F are schematic cross-sectional views of respective steps for forming the structure of the third embodiment. FIG. 8 (a) is shown in FIG.
Since it is similar to (a), the description is omitted.

FIG. 8B is almost the same as FIG. 2B, but in this case, no piston is formed in the recess 203-a.

Next, as shown in FIG. 8C, a lower insulating layer 111, a heater layer 109, and an upper insulating layer 110 are sequentially formed. The material of each insulating layer, the material and shape of the heater layer, the advantages of forming the heater layer on the sacrificial layer, and the like are the same as those described with reference to FIG.

Next, as shown in FIG. 8D, the concave portion 203-
The piston 603, the buckling member 606, and the wiring pattern 210 are formed on a by plating. This is because an underlying conductive layer (for example, Ni, Ta, Ag) is completely formed on the entire surface before plating.
It can be performed by forming a film having a thickness of 01 to 1 μm, forming a pattern of a photoresist on the portion 211 where plating is unnecessary, and removing the resist after plating. In this case, it is effective to rotate the substrate 101 or perform film formation from an oblique direction when forming the conductive layer so that the conductive layer is not broken by the corner portion 217 of the recess 203-a. Further, it is also particularly effective to adopt a film forming method such as CVD capable of excellently covering the step.

The wiring pattern 210 is formed so as to be connected to the heater layer 109. As a material forming the buckling body 606, Ni, Cu, Co, P, S or an alloy thereof can be used. Especially Ni, Cu, C
o has a relatively large thermal expansion coefficient and Young's modulus, so that the strain energy stored in the buckling body can be increased and a large discharge energy can be obtained. In addition, when these alloys are used, the strength of the buckling member 606 is improved, the life is extended, the Young's modulus is increased, the strain energy is increased, and the ejection energy is increased, which is described in the description of FIG. 2D. Is the same as

In the case of this embodiment, the buckling body 606, the piston 603 and the wiring portion are plated at the same thickness at one time. By doing so, it is not necessary to provide a thick portion in a part, and the entire thickness can be made uniform. When plating, when the film thickness of each part is different, internal stress is often generated inside the film, and residual stress may occur after the film is formed, or the film may peel off due to the residual stress. If the plating is performed evenly, such a problem can be solved, the generation of internal stress can be suppressed, deformation due to stress after creation can be avoided, and a precise structure can be created.

Next, as shown in FIG. 8 (e), the entire substrate 101 which has been subjected to the above-mentioned treatment is dipped in a KOH solution for anisotropic etching to remove the residual portion 212. At this time, if aluminum is used for the sacrificial layer 204, the etching of aluminum proceeds simultaneously with the anisotropic etching, and the sacrificial layer 204 is removed at the same time, so that the process can be simplified. This is similar to that described with reference to FIG. Next, as shown in FIG. 8F, the orifice plate 115 having the nozzle 115 is adhered by the adhesive layer 114. As the adhesive layer 114, an ultraviolet curable adhesive or a thermosetting adhesive can be used. As in the first and second embodiments, the cavity can be easily isolated by forming the plan view of the pattern of the adhesive layer 114 as shown in FIG.

[0090]

Since the head having a simple structure can be realized, the cost can be reduced. Moreover, since the structure is easily integrated, a small head can be realized, and at the same time, a high resolution head can be obtained and high quality printing can be performed. Since the gap between the ink supply holes is narrow, it is possible to prevent backflow of ink during ejection, and it is possible to realize a highly efficient head. Since it is easy to increase the resistance of the backflow, it is easy to improve the efficiency. Power consumption can be reduced by improving efficiency. If the heater layer is separately provided, the current consumption can be reduced, the current capacity of the drive power source can be reduced, and the drive device can be made compact and lightweight.

Since the cavity can be easily formed, the manufacturing cost is reduced. In addition, since ink can be completely isolated, it is possible to improve efficiency and prevent crosstalk between adjacent heads.

Since the supply holes, gaps, etc. can be formed accurately, the production accuracy is improved and a highly integrated head can be obtained.
A small head with high resolution can be obtained. In addition, a head with high yield and little variation can be obtained during production. When a substrate having a crystal plane orientation of (100) is used, a head with little change in characteristics can be obtained, and a head with high environmental resistance can be obtained during use. In addition, an inexpensive head can be obtained by using a substrate having a crystal plane orientation of (110).

When the piston has a shell structure, the rigidity of the piston can be increased even if the thickness is reduced, and as a result, a highly efficient head can be obtained without being deformed during driving. Further, since a thin and lightweight piston having high rigidity can be manufactured, a head having a high frequency response can be obtained. Since the plating thickness can be made uniform and the residual stress can be reduced, a precise structure can be formed, and a highly integrated head can be manufactured with high yield.

Since the size and shape of each part can be accurately created, a head having uniform characteristics can be formed at one time, and the head manufacturing cost can be reduced. In addition, since variations at the time of production can be reduced, characteristics and yield can be improved. Furthermore, since the size of the gap is extremely small and can be accurately formed, the effect of preventing backflow is great, the efficiency is improved, and as a result, a compact head with low power consumption can be obtained. Since the fabrication can be performed all at once using anisotropic etching, the fabrication process is simplified and the cost can be reduced.

When aluminum is used as the sacrificial layer, a fine pattern can be easily formed, so that a compact head having high integration and high resolution can be constructed. Since a thin gap can be formed and ink backflow can be prevented, a highly efficient head can be configured, and a compact and low power consumption head can be obtained. Since the sacrificial layer is removed simultaneously with the anisotropic silicon etching, the process can be simplified.

When plating is used to form the buckling body, the piston, etc., a film having a small residual stress can be easily formed. Therefore, a fine and precise structure can be formed, and a compact and highly integrated head can be formed. In addition, a material having a large buckling body strain energy such as Ni, Co, or Cu can be used,
An inkjet head with a high ejection speed can be obtained, and printing quality can be improved. Further, when plating is used, a shell structure piston can be easily formed, a lightweight and highly rigid piston having a high frequency response can be obtained, and a head having high printing quality at high speed can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a first embodiment of the present invention.

2 (a) to 2 (f) are schematic cross-sectional views of respective steps of manufacturing the first embodiment.

FIG. 3 is a plan view of an adhesive layer and its periphery.

FIG. 4 is a schematic sectional view of a second embodiment of the present invention.

5 (a) to 5 (f) are schematic cross-sectional views of respective steps of manufacturing the second embodiment.

6A and 6B are a cross-sectional view of a third embodiment of the present invention and a plan view of an adhesive layer and its periphery, respectively.

FIG. 7 is a sectional perspective view of a buckling body and a piston according to a third embodiment.

8A to 8F are schematic cross-sectional views of respective steps of manufacturing the third embodiment.

9A and 9B are explanatory views before and after deformation of the buckling body in the first embodiment, respectively.

10 (a) and 10 (b) are explanatory views of a buckling body of the second embodiment before and after deformation, respectively.

11 (a) and 11 (b) are explanatory views of the buckling body of the second embodiment before and after deformation, respectively.

12A and 12B are explanatory diagrams of ink ejection before and after deformation of the buckling body, respectively.

13A and 13B are cross-sectional views of a conventional piezoelectric element before and after deformation, respectively.

FIG. 14 is an exploded perspective view of another conventional example.

[Explanation of symbols]

 101 Substrate 102 Ink Supply Hole 103 Piston 104 Wall Surface 105 Gap 106 Buckling Member 107 Fixing Part 108 Gap 109 Heater Layer 110 Upper Insulating Layer 111 Lower Insulating Layer 112 Oxide Film 113 Wiring Layer 114 Adhesive Layer 115 Orifice Plate 116 Nozzle 117 Cavity

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yorisei Ishii 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Shingo Abe 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Incorporated (72) Inventor Kenji Ota 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture

Claims (8)

[Claims] 1. A substrate having an ink supply hole, a buckling member that is subjected to buckling deformation by heating and has both ends fixed to one surface of the substrate across the ink supply hole, and means for heating the buckling member. , A piston part integrally formed with one surface of the buckling body so as to reciprocate along the wall surface of the ink supply hole, and attached to the other surface of the buckling body via an adhesive layer It has an orifice plate having a nozzle, a cavity surrounded by the orifice plate, an adhesive layer and a buckling body, and ejects ink from the nozzle by pressurizing the piston by the buckling deformation of the buckling body. And inkjet head. 2. The ink jet head according to claim 1, wherein the heights of the material forming the buckling member and the adhesive surface of the adhesive layer are substantially equal over the entire surface. 3. The ink jet head according to claim 1, wherein the material of the substrate is single crystal silicon, and the wall surface of the ink supply hole is composed of the (111) plane. 4. The ink jet head according to claim 1, wherein the piston portion is integrally formed with the buckling body by a shell structure. 5. A step of forming a concave portion corresponding to an ink supply hole in a substrate, a step of forming a sacrificial layer inside the concave portion and a buckling body lower portion formed on the upper surface of the substrate, and a buckling body on the upper surface of the substrate. A method for manufacturing an inkjet head, comprising: a step of forming a piston portion inside the concave portion; and a step of forming an ink supply hole and removing a sacrificial layer thereafter. 6. The method for manufacturing an ink jet head according to claim 5, wherein a silicon single crystal is used for the substrate, and the recesses are formed by silicon anisotropic etching. 7. The method for manufacturing an inkjet head according to claim 5, wherein the sacrificial layer formed below the buckling body is formed of an aluminum thin film. 8. The method of manufacturing an ink jet head according to claim 5, wherein the piston portion and the buckling member are simultaneously formed by plating.