JPH068449A - Ink jet head - Google Patents

Abstract

PURPOSE:To enable a static electricity-using type ink jet head to be more compactly densified by a method wherein a plurality of nozzles are formed at equal intervals respectively to one side surface and the other side surface of a Si monocrystal substrate. CONSTITUTION:A Si substrate 1 is a monocrystal Si substrate of which a crystal face direction is (100). A plurality of nozzles 4a, a cavity 5a interconnected to each nozzle 4 of which a bottom wall is of a frequency 6a, an ink feed passage 8a which is formed at an end part on an opposite side to the nozzle 4a in each cavity 5a, and a common ink chamber 7 for feeding ink to each feed passage 8a are formed to a front side face of the substrate 1. Further, a nozzle 4b, a diaphragm 6b, a cavity 5b, an ink feed passage 8b, and the ink chamber 7 are formed in the same way to a rear side face of the substrate 1. An ink jet head which is of a higher density by being compared with a case wherein the nozzles or the like are formed only on one side of the Si substrate will be obtained thus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head which is a main part of a small and high density ink jet recording apparatus manufactured by applying a micromachining technique.

[0002]

2. Description of the Related Art An ink jet recording apparatus has many advantages such as extremely low noise during recording, high speed printing, and printing on inexpensive plain paper. The so-called ink-on-demand method, in which ink droplets are ejected only when necessary for recording, is currently in the mainstream because it does not require recovery of ink droplets required for recording.

In this ink-on-demand type ink jet head, as shown in Japanese Patent Publication No. 2-51734, the driving means is a piezoelectric element, and as shown in Japanese Patent Publication No. 61-59911. There is a method in which the ink is ejected by the pressure generated by heating the ink and generating bubbles.

[0004]

However, the above-mentioned conventional ink jet head has the following problems.

In the former method using a piezoelectric element,
The step of sticking the piezoelectric element chip to each vibration plate for generating pressure in the pressure chamber is complicated, and particularly high speed and high printing quality are required for printing by the recent inkjet recording device, In order to achieve this, in forming multiple nozzles and increasing the density of nozzles, it is extremely complicated to finely process the piezoelectric element and bond it to each diaphragm. In addition, in high density, the piezoelectric element has a width of 1
Although it has become necessary to machine with 0 to several tens of microns, there has been a problem that the variation in printing quality becomes large in the size and shape accuracy in the conventional machining.

Further, in the latter method of heating ink, since the driving means is formed of a thin-film resistance heating element, the above problems did not exist, but the rapid heating / cooling of the driving means is not possible. There is a problem that the life of the ink jet head is short because the resistance heating element is damaged by repeated or impact when bubbles disappear.

In order to solve these problems, the present applicant has applied for a patent for an ink jet recording apparatus of a type in which a vibrating plate for generating a pressure in a pressure chamber as a driving means is deformed by electrostatic force (Japanese Patent Application No. 3-234537). No.), but this method has the advantages of small size, high density, high print quality, and long life.

An object of the present invention is to provide an ink jet head of a higher density in an ink jet head of a system using electrostatic force.

[0009]

An ink jet head of the present invention comprises a plurality of nozzles for ejecting ink droplets,
A pressure chamber communicating with each of the nozzles, a vibrating plate forming at least one wall of the pressure chamber, a common ink chamber for supplying ink to the pressure chamber, and a driving unit for causing deformation of the vibrating plate. An inkjet head comprising electrodes for deforming the vibrating plate by an electrostatic force, the driving unit including a Si single crystal substrate having a (100) plane orientation as a constituent member, and one surface of the Si single crystal substrate and the other surface. A plurality of the nozzles are formed at equal intervals on each of the surfaces, and the nozzles formed on the one surface and the other surface cut a predetermined position of the Si single crystal substrate. In the end surface generated by the above, the nozzles are arranged in a staggered manner, and further, in the nozzle formed on the one surface and the nozzle formed on the other surface, between the nozzles in the longitudinal direction of the end surface. Characterized in that it is arranged to be shifted by 1/2 from each other as a unit length.

When etching an Si single crystal using an alkaline solution, so-called anisotropic etching, in which the etching rate greatly differs depending on the crystal plane orientation, can be utilized, and by utilizing this, various three-dimensional shapes can be accurately formed. It can be processed. Furthermore, the so-called "micromachining technology", which forms microdevices by combining processing using photolithography, thin film formation, etching, and other technologies that have been cultivated in IC manufacturing technology, is currently receiving attention. However, the present invention provides a high-performance inkjet head by subjecting a Si single crystal to highly precise three-dimensional processing by a micromachining technique.

In the Si single crystal substrate having the (100) plane orientation,
In the alkaline etching, the (111) plane having the smallest etching rate intersects the substrate surface at an angle of about 55 degrees, that is, the space shape surrounded by the inclined surface of 55 degrees can be formed with high accuracy. By applying this space shape as a pressure chamber (cavity), it is possible to provide an ink jet head of high printing quality in which the variation of the pressure chamber volume is small and therefore the ejected ink volume is constant.

In the ink jet head of the present system which ejects ink by deforming / restoring the vibrating plate, assuming that the width of the vibrating plate 6 is W ₁ and the depth of the cavity 5 is D shown in FIG. The width W ₂ of

[0013]

[Equation 1]

When a plurality of nozzles are formed on one surface of the Si single crystal substrate, the nozzle pitch cannot be made smaller than several 1, but as shown in FIG.
According to the configuration of the present invention in which the cavities are formed on both surfaces of the i single crystal substrate, the nozzle pitch can be reduced.
The advantage of the present invention is that the wall 1 that forms between the cavity formed on one surface of the Si single crystal substrate and the cavity formed on the other surface closest to the cavity 1
Since 7 has both (111) faces 18 on both sides, the walls are not penetrated by etching in the cavity forming process by etching, and the shape according to the design dimension can be formed.

[0015]

The operation principle of the ink jet head of the present invention is as follows.
By applying a pulse voltage to the electrode or the diaphragm, by applying a positive or negative charge to the electrode or the diaphragm, the diaphragm is deformed by electrostatic attraction or repulsion,
The ink in the pressure chamber is ejected from the nozzle.

[0016]

【Example】

(Embodiment 1) Hereinafter, a detailed description will be given based on a first embodiment of the present invention.

FIG. 1 is an exploded perspective view showing the structure of an ink jet head according to the first embodiment of the present invention, showing a partial cross section. As shown in FIG. 1, the ink jet head of this embodiment has a Si substrate 1 and electrodes 11a on which nozzles 4a and 4b, cavities 5a and 5b, diaphragms 6a and 6b, etc. are formed by alkali anisotropic etching.
11b, grooves 12a and 12 for forming the gap portion
It has a structure in which glass substrates 2a and 2b on which b and the like are respectively formed are laminated and joined.

The Si substrate 1 is a single crystal Si substrate having a crystal plane orientation of (100), and the front surface (upper surface in FIG. 1) of the Si substrate 1 has a plurality of nozzles 4a. A cavity 5a communicating with each nozzle 4a and having a bottom wall as a vibrating plate 6a, and an ink supply path 8a formed at an end of each cavity 5a opposite to the nozzle 4a.
And a common ink chamber 7 for supplying ink to each ink supply path 8a is formed, and the back surface (lower surface in FIG. 1) of the Si substrate 1 similarly has nozzles 4b, Although the vibration plate 6b, the cavity 5b, the ink supply path 8b, and the ink chamber 7 are formed, in the present embodiment, the ink chamber 7 is formed.
Is formed by penetrating through both sides of the Si substrate 1, and is therefore commonly used on the front side and the back side of the Si substrate 1.

The Si substrate 1 is used for the glass substrates 2a and 2b.
Electrodes 11a and 11b arranged facing the vibrating plates 6a and 6b formed above, and grooves 12a for maintaining a facing gap (gap) between the vibrating plates 6a and 6b and the electrodes 11a and 11b. 12b is formed,
The cavities 5a and 5b are respectively bonded to the back side and the front side of the Si substrate 1 so that they serve as pressure chambers for pressurizing ink.

FIG. 2 shows a manufacturing process of the Si substrate 1 shown in FIG.
Shown in.

First, both sides of a (100) plane-oriented Si wafer are mirror-polished to form a Si substrate 1 having a thickness of 200 μm (FIG. 2A), and the Si substrate 1 is exposed to O ₂ and water vapor atmosphere. After thermal oxidation treatment at 1100 degrees Celsius for 4 hours,
A SiO ₂ film 15 having a thickness of 1 micron is formed on both sides of the Si substrate 1.
a and 15b are formed (FIG. 2 (b)). SiO ₂
The films 15a and 15b are used as an etching resistant material.

[0022] Next, on the SiO ₂ film 15a, a photoresist pattern 16a corresponding to the shape of a nozzle 4a · cavity 5a · ink chamber 7 (not shown), also on the SiO ₂ film 15b is , Similarly nozzle 4
b, a cavity 5b, a photoresist pattern 16b (not shown) corresponding to the shape of the ink chamber 7, etc. is formed,
With the hydrofluoric acid-based etching solution, the SiO ₂ films 15a and 1
The exposed portion of 5b is removed by etching to remove the photoresist patterns 16a and 16b (FIG. 2C). The photoresist patterns 16a and 16b are formed by aligning their positions on the micron order with a double-sided aligner. Also, photoresist pattern 1
The design dimension value of each part of the photomask pattern which is the source of 6a and 16b was determined as follows.

The design dimension value of each component is determined from the ink ejection characteristics required for the ink jet head of this structure. In this embodiment, the widths W ₁ of the vibration plates 6a and 6b are 500 μm and the thickness t is 30 μm.

On a (100) Si substrate, (111)
The plane is a crystal structure with respect to the (100) plane which is the substrate surface,
Since they intersect at an angle of about 55 degrees, when the dimensions of the structure formed in the (100) Si substrate are determined as described above, the mask pattern of the etching resistant material is unique to the thickness of the Si substrate. It is determined. As shown in FIG.
The width W ₂ of the upper end of the cavity 5a is set to 740 microns,
When the Si substrate 1 is etched to 170 μm, a diaphragm 6a having a width W ₁ of 500 μm and a thickness t of 30 μm is obtained.

In actual etching, the (111) plane is etched (undercut) little by little, and the dimension W ₂ in FIG. 3 becomes slightly larger than the mask pattern width W ₃ . Therefore, the width W _{2 of the} photomask pattern 16a
Needs to be corrected to be smaller by the amount of the undercut dimension of the (111) plane 18, and in this embodiment, is set to 730 μm. Also, the space (or pitch) between adjacent cavities
Is restricted by the position of the cavity 5b formed on the back surface side of the Si substrate 1. That is, in the ink jet head of the present embodiment, the cavity 5a and the cavity 5b formed in the vicinity of the cavity 5a are separated by the wall portion 17 having the (111) plane 18 on two sides as described above. However, the thickness of the wall portion 17 needs to have a certain thickness or more in consideration of the crosstalk, that is, the influence on the ejection characteristics to the adjacent cavities. In the present embodiment, the thickness of the wall portion 17 is large. t '
Value was 40 microns. A plurality of cavities 5 are formed on the front surface and the back surface of the Si substrate 1 based on the value of the thickness t '.
The dimensions and spacing of a and 5b are determined. That is, the pitch interval is 1296 microns, and this value is S
Since it is a value on one surface on the i substrate, the nozzle density is doubled on both surfaces, that is, 648 microns.

Si substrate 1 at the stage of step (c) of FIG.
Then, etching with an alkaline solution is performed. As an etching solution, an aqueous solution of potassium hydroxide containing isopropyl alcohol was used to perform etching of a predetermined amount of 170 μm (FIG. 2 (d)). At this time, the nozzles 4a and 4b, the ink supply paths 8a and 8b, the ink chamber 7 and the like are formed at the same time as the cavities 5a and 5b, but the etching resistant mask pattern corresponding to the nozzles and the ink supply path has a narrow width. The two (111) planes that appear due to etching intersect at a shallower depth than the cavities 5a and 5b, and further etching hardly progresses. Further, since the ink chamber 7 has the same etching-resistant mask pattern on both sides of the Si substrate 1, 100 μm, which is ½ of the thickness of the Si substrate 1, is etched from both sides. A through hole is formed at this point, and the ink chambers are common on both sides.

Next, the SiO ₂ films 15a and 15a, which are the etching resistant mask material remaining on both sides of the Si substrate 1, are formed.
5b was completely removed with a hydrofluoric acid-based etching solution (see FIG. 2).
(E)), Si substrate 1 is completed.

Next, the manufacturing process of the glass substrates 2a and 2b will be described.

Vibration plates 6a and 6b formed on the Si substrate 1
At the same width as the diaphragms 6a and 6b (7
30 μm) and grooves 12a and 12b for forming gaps at the same pitch are formed by etching using a hydrofluoric acid-based etching solution. As the groove depth, the design dimension value of the gap length is 0.50 micron, and the value is adjusted to 0.60 micron by adding 0.10 micron which is the material thickness of the electrodes 11a and 11b to this value in the etching process. I do. The electrode material is Au (gold) /
A two-layer film of Cr (chrome) is formed on the entire surfaces of the glass substrates 2a and 2b by a sputtering method, and then an unnecessary portion is removed by etching. In this example, the thickness of Cr was 0.05 μm, the thickness of Au was 0.95 μm, and a two-layer film was formed by continuous sputtering.

In addition, a hole 13 for ink supply is formed in the glass substrate 2b at a position corresponding to the ink chamber 7 on the Si substrate 1.

Next, as shown in FIG. 4, the Si substrate 1 and the glass substrates 2a and 2b are joined. The joining is by the anodic joining method. After the Si substrate 1 and the glass substrates 2a and 2b are aligned, each member is butted, and the entire butted member on the hot plate 20 is sandwiched between the upper electrode 21 and the lower electrode 22, and the temperature is 310 degrees Celsius. To 800 ° C. with the Si substrate on the positive side and the glass substrates 2a and 2b on the negative side.
By applying a DC voltage of V for 10 minutes, the glass-
A bonded body of Si-glass is obtained.

Finally, the obtained bonded body is cut by dicing to obtain an ink jet head.

As described above, an ink jet head having a high density was obtained as compared with the case where nozzles and the like were formed only on one side of the Si substrate. In actual printing, each vibrating plate is vibrated by the oscillation circuits 14a and 14b (not shown) corresponding to each vibrating plate 6a and 6b,
The ink in each pressure chamber is pressurized, and ink droplets are ejected from each nozzle 4a and 4b.

(Second Embodiment) The second embodiment of the present invention will be described below in detail.

FIG. 5 shows a sectional view of an ink jet head in the second embodiment of the present invention. The present embodiment has a structure in which two ink jet heads shown in the first embodiment of the present invention are laminated, and therefore the nozzle density is further doubled. Since the Si substrates 1a and 1b shown in FIG. 5 are both manufactured by the same manufacturing method as in the case of the first embodiment of the present invention, the description of the manufacturing process is omitted. The glass substrates 2c and 2e are also manufactured by the same method as the glass substrates 2a and 2b in the first embodiment of the present invention. However, a hole 13 (not shown) for ink supply is also formed in the glass substrate 2e.

In order to evenly disperse the four nozzle rows (4c, 4d, 4e, 4f) in the longitudinal direction (x direction in FIG. 5) of the end surface of the Si substrate of the ink jet head of this embodiment, the nozzles 4c are arranged. With the nozzle 4e, the distance between nozzles formed adjacently on the same surface of the Si substrate is set to 1 and
Since the Si substrates 1a and 1b are stacked and assembled so as to be displaced by / 4, the electrode 11d formed on the glass substrate 2d
The positions of and 11e are shifted by 1/4. Although the glass substrate 2d can have any thickness, the nozzle 4
The distance between the nozzle row consisting of d and the nozzle row consisting of the nozzle 4e must be an appropriate value. In this embodiment, S
The thickness was set to 200 μm, which is the same thickness as the i substrates 1a and 1b.

After the alignment between the members of the Si substrates 1a and 1b and the glass substrates 2c, 2d and 2e, Si-- by means of the anodic bonding method as in the first embodiment of the present invention.
The glass members were joined to integrate each member. In the ink jet head obtained here, the nozzle spacing (pitch) is 1296 microns on the same Si surface, but since the four nozzle rows are stacked in a form shifted by 1/4 pitch, the pitch is 324 microns. It will be considerable.

Finally, the obtained bonded body is cut by dicing to obtain an ink jet head. As described above, by stacking two Si substrates having nozzles and the like formed on both sides thereof, an ink jet head having a higher density was obtained.

Further, in addition to the above structure, by further laminating a Si substrate and glass and increasing the number of nozzle rows to 6, 8, ... Can be achieved.

(Third Embodiment) The third embodiment of the present invention will be described in detail below.

FIG. 6 is an exploded perspective view showing the structure of an ink jet head in the third embodiment of the present invention, showing a partial cross section.

As shown in FIG. 6, the ink jet head of this embodiment has nozzles 4i and 4h, pressure chambers 5i and 5h,
Si substrate 1c in which diaphragms 6i and 6h and the like are formed by alkali anisotropic etching, electrodes 11i and 11h (not shown), and Si ₂ spacers 23i and 23h and the like for forming gap portions are formed in the Si substrate 1c. It has a structure in which 24 and 30 are laminated and joined. Si shown in FIG.
Since the substrate 1c is manufactured by the same manufacturing method as in the first embodiment of the present invention, the description of the manufacturing process is omitted.

The manufacturing process of the Si substrate 24 is shown in FIG. S
Since the i substrates 24 and 30 are basically manufactured in the same process, the manufacturing process of the Si substrate 30 will be omitted.

First, an n-type Si substrate 2 having a (100) plane orientation
The front surface (upper side in FIG. 7) of No. 4 is mirror-polished, and the Si substrate 24 is subjected to thermal oxidation treatment at 1100 degrees Celsius for a predetermined time in an atmosphere of O ₂ and water vapor. _Two films 25a and 25b are formed (FIG. 7).
(A)).

Then, a photoresist pattern 26a corresponding to the shape of the electrode 11i is formed on the SiO ₂ film 25a.
(Not shown) is formed, the exposed portion of the SiO ₂ film 25a is removed by etching with a hydrofluoric acid-based etching solution, and the photoresist pattern 26a is removed (FIG. 7).
(B)).

Next, B to the exposed portion 27 of the Si substrate 24
Dope (boron). The processing method is as follows. Wherein the Si substrate 24 were fixed with quartz holder in a quartz tube, for introducing the vapor was bubbled BBr ₃ and N ₂ as a carrier in the quartz tube together with O _2. After processing at 1100 degrees Celsius for a predetermined time, the Si substrate 24 is light-etched with a hydrofluoric acid-based etching solution, and then O
Drive-in was performed in ₂ to form the exposed Si portion 27 as a p-type layer 28 (FIG. 7C). The p-type layer is shown in FIG.
And functions as the electrode 11i. In the step of FIG. 7C, the thickness of the SiO ₂ films 25a and 25b on both sides of the Si substrate 24 increases, but in the present embodiment, the SiO ₂ film 25a is formed on the diaphragm 6 in FIG.
i and the electrode 11i, the p-type layer 28 (electrode 11
A photoresist pattern 29 (not shown) corresponding to the shape of i) is formed and SiO 2 is formed using a hydrofluoric acid-based etching solution.
₂ The exposed portion of the film 25a is removed by etching (see FIG.
(D)), the Si substrate 24 shown in FIG. 6 is formed.

In the ink jet head of this embodiment, the vibrating plate 6i is used as in the case of the first embodiment of the present invention.
The dimensions of distance between the electrode 11i is determined to 0.50 microns on the ink ejection characteristics of the ink jet head, in FIG. 7 (c) step, the SiO ₂ film 25
The process was performed such that the thickness of a was 0.50 micron.

The Si substrate 24 in FIG. 6 formed by the above process and the Si substrate 30 manufactured in the same process.
The Si substrate 1c and the Si substrate 1c are joined by a Si-Si direct joining method. The joining process is as follows.

First, the Si substrates 1c, 24 and 30 are washed with a mixed solution of sulfuric acid and hydrogen peroxide (100 ° C.) and dried, and then the positions of the corresponding patterns of the Si substrates 1c and 24 and 30 are positioned. After performing the matching, the three substrates are stacked. The integrated Si substrates 1c, 24 and 30 are heat-treated at 1100 ° C. for 1 hour in an N ₂ atmosphere to obtain a strong bonded state.

Finally, the obtained bonded body is cut by dicing to obtain an ink jet head.

As described above, also in this embodiment, an ink jet head having a high density was obtained as in the case of the first embodiment of the present invention.

Further, as in the case of the second embodiment of the present invention, S in which nozzles and the like are formed on both side surfaces in this embodiment.
i substrate and Si with electrodes formed at predetermined positions on both sides
By alternately laminating the substrates, it is possible to easily manufacture a higher density inkjet head.

[0053]

As described above, the present invention has the following effects.

Nozzles, cavities, etc. are equally spaced on both sides of the Si single crystal substrate, and the nozzles formed on one side and the other side are the end faces of the Si single crystal substrate. In the staggered arrangement, the high density ink jet head can be obtained. In addition, by stacking and assembling a plurality of Si substrates having nozzle cavities formed on both sides thereof so that the respective nozzles are optimally arranged,
Further, there is an effect that a high-density inkjet head can be obtained.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a structure of an inkjet head according to a first embodiment of the present invention.

FIG. 2 is a manufacturing process diagram of the ink jet head in the first embodiment of the invention.

FIG. 3 is a diagram showing a relationship between dimensions of respective parts of the inkjet head in the first embodiment of the present invention.

FIG. 4 is a diagram showing a method of joining the inkjet heads according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the structure of an inkjet head according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing the structure of an inkjet head according to a third embodiment of the present invention.

FIG. 7 is a manufacturing process diagram of an inkjet head according to a third embodiment of the present invention.

FIG. 8 is a diagram showing a dimensional relationship between a vibration plate and a cavity of an inkjet head in the first, second and third embodiments of the present invention.

FIG. 9 is a cross-sectional view showing the positional relationship of cavities of the inkjet head in the first, second and third embodiments of the present invention.

[Explanation of symbols]

1 Si substrate 2a, 2b Glass substrate 4a, 4b Nozzle 5a, 5b Cavity 6a, 6b Vibration plate 7 Ink chamber 8a, 8b Ink supply path 11a, 11b Electrode 12a, 12b Groove 13 Hole 14a, 14b Oscillation circuit 15a, 15b SiO ₂ Films 16a, 16b Photoresist pattern 17 Wall 18 (111) surface

Front page continuation (72) Inventor Shinichi Yotsuya 3-5 Yamato, Suwa City, Nagano Seiko Epson Corporation

Claims (3)

[Claims] 1. A plurality of nozzles for ejecting ink droplets, pressure chambers that communicate with each of the nozzles, a diaphragm that forms at least one wall of the pressure chambers, and ink is supplied to the pressure chambers. In the ink jet head including a common ink chamber and a driving unit that causes the vibration plate to deform, the driving unit deforms the vibration plate by an electrostatic force. An inkjet head comprising a substrate as a constituent member, wherein a plurality of nozzles are formed at equal intervals on one surface and the other surface of the Si single crystal substrate. 2. The nozzles formed on the one surface and the other surface are arranged in a staggered manner on an end surface formed by cutting a predetermined position of the Si single crystal substrate. Item 2. The inkjet head according to item 1. 3. A coordinate value of a nozzle formed on the other surface on a coordinate axis imaginary in the longitudinal direction of the end surface,
The difference from the coordinate value of the nozzle closest to the nozzle and formed on the one surface is 0.
The inkjet head according to claim 2, wherein the inkjet head is 5.