JP3233189B2 - Ink jet recording head and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head using a silicon single crystal substrate as a spacer forming member, and a method of manufacturing the same.

[0002]

2. Description of the Related Art An ink jet recording head of a type in which a pressure plate is formed by bonding a nozzle plate having a nozzle opening formed thereon and a vibration plate to both surfaces of a spacer and the vibration plate is deformed by a piezoelectric vibrator is used. Since thermal energy is not used as a driving source for flying the ink, there is no deterioration of the ink due to heat, and it is possible to eject color ink which is easily deteriorated by heat, and furthermore, by adjusting the displacement of the piezoelectric vibrator. Since the ink amount of the ink droplet can be freely adjusted, the head is optimal for configuring a printer for high quality color printing.

On the other hand, in order to perform higher quality color printing using an ink jet recording head, a higher resolution is required. Therefore, the size of the piezoelectric vibrator and the partition walls of the spacer member is inevitably reduced. High precision is required for processing members and assembling members.

[0004] For this reason, ink jet recording is performed by applying a so-called micromachining technique, which is a part manufacturing technique using anisotropic etching of a silicon single crystal substrate, which can process a fine shape with high accuracy by a relatively simple technique. It has been studied to process the members constituting the head, and various techniques and methods have been proposed (for example, Japanese Patent Application Laid-Open No. Hei 3-187755, Japanese Patent Application Laid-Open No. Hei 3-187756, Japanese Patent Application Laid-Open No. Hei 3-87757, JP-A-4-2790, JP-A-4-129745, JP-A-5-62
No. 964).

In order to print color images and characters with high quality, not only the arrangement density of the nozzle openings is increased but also the area of one dot itself is changed in accordance with the image signal, that is, the so-called area gradation is used. Printing is required. For this purpose, it is necessary to realize a recording head capable of discharging ink droplets a plurality of times for one pixel by minimizing the amount of ink discharged by one ink droplet as much as possible and enabling high-speed driving. There is.

For this purpose, first, it is necessary to reduce the displacement of the piezoelectric vibrator and instantaneously reflect the change in the volume of the pressure generating chamber. Next, in order to link a small change in volume of the pressure generating chamber to ejection of ink droplets, it is necessary to minimize pressure loss in the pressure generating chamber. It is important to increase the rigidity of the pressure generating chamber in order to efficiently connect the displacement of the piezoelectric vibrator to the change in volume of the pressure generating chamber, and to reduce the pressure loss in the pressure generating chamber, It is an inevitable task to make the volume of the chamber as small as possible.

To reduce the volume of the pressure generating chamber, it is conceivable to reduce the opening area. However, considering the processing accuracy of the piezoelectric vibrator in contact with the opening, the arrangement pitch of the nozzle openings is at most limited. Therefore, after all, a method of reducing the depth by reducing the depth of the pressure generating chamber has to be adopted.

[0008]

However, on the other hand,
Considering the handling of spacers in the assembly process, etc.,
The thickness of the silicon single crystal substrate must be at least 220 μm or more. If the thickness is smaller than this, there is a problem that the strength is low and breakage occurs during the assembly process.

For this reason, the pressure generating chamber can be formed shallower than the thickness of the silicon single crystal substrate by applying so-called half etching, in which the silicon single crystal substrate is etched from only one surface thereof. However, when a silicon single crystal substrate is used as the spacer, a nozzle plate is provided to face the pressure generating chamber, and the nozzle opening communicates with the pressure generating chamber.
It is necessary to form a penetrating portion for communicating from the pressure generating chamber to the surface on which the nozzle plate is provided.

However, as is well known, in order to form the through portion H by anisotropic etching, as shown in FIG. 5, at least about 1.7 times (√3 times) the thickness of the silicon single crystal substrate. It is necessary to set the length of the opening. When a substrate having a length of 220 μm or more is used, the minimum length of the through portion is about 380 μm.

In this case, not only does the volume of the communication hole cause an increase in the volume of the pressure generating chamber, but also the communication hole has a thickness of the silicon single crystal substrate, ie, 220 μm.
In addition, since the length in the longitudinal direction is as large as 380 μm, the rigidity of the partition walls decreases when the partition walls of the pressure generation chambers are inevitably thin, such as when the pressure generating chambers are arranged at high density. There is a problem of doing it.

The present invention has been made in view of the above circumstances, and an object thereof is to use a silicon single crystal substrate as thick as a base material and to form a pressure generating chamber shallower than the thickness. To provide a novel ink jet recording head provided with the same.

Another object of the present invention is to propose a method of manufacturing the above-mentioned ink jet recording head.

[0014]

According to the present invention, there is provided an anti-etching layer having durability on an etching solution used for anisotropic etching of a silicon single crystal. Silicon single crystal substrate
In addition, the pressure generation chamber by anisotropic etching, common ink
Chamber, and the pressure generating chamber and a common ink chamber are connected.
A spacer having an ink supply port formed therein, a nozzle plate having nozzle openings formed on one surface of the spacer at a pitch corresponding to the pressure generation chamber, and an expansion of the pressure generation chamber on the other surface of the spacer. In an ink jet recording head provided with a contracting diaphragm, the pressure generating chamber is formed as a concave portion by half etching of the silicon single crystal substrate, the common ink chamber is formed as a through hole by full etching, and Open the nozzle
The nozzle communication hole connecting the mouth is formed as a through hole by laser processing .

[0015]

The nozzle communication hole requiring the smallest through-hole can be formed by laser processing, so that there is no restriction on the thickness of the substrate, and it is smoother than that obtained by anisotropic etching, and a cylindrical shape is desirable as a flow path. Can be formed.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a view showing an embodiment of the present invention with a cross-sectional structure in the vicinity of a pressure generating chamber. In the drawing, reference numeral 1 denotes a spacer which is a feature of the present invention and has a predetermined crystal orientation, for example, a crystal on a surface. A silicon single crystal substrate having an orientation (110), and having a thickness W of the silicon single crystal substrate on one surface;
A pressure generating chamber 2 having a depth D smaller than that of the ink supply port 3 and a common ink chamber 4 formed as a through-hole on the other side so as to communicate with the ink supply port 3 are provided. In addition, a nozzle communication hole 6 is formed at the other end of the pressure generation chamber 2, which is a through hole connecting the pressure generation chamber 2 and the nozzle opening 5.

The pressure generating chamber 2 and the ink supply port 3 are formed as shallow recesses by performing anisotropic etching only on one surface of a silicon single crystal substrate serving as a base material of the spacer 1. 4 is formed as a through hole by anisotropically etching a silicon single crystal substrate because its opening area is large.

On the other hand, since the diameter of the nozzle communication hole 6 must be 1 / √3 or less as compared with the thickness of the silicon single crystal substrate, the nozzle communication hole 6 is formed by a laser using copper ions. As a result, the nozzle communication hole 6 is formed in a cylindrical shape with a circular cross section, so that ink can be supplied to the nozzle opening 5 without stagnation as compared with a case where the nozzle communication hole 6 is formed by anisotropic etching. .

The spacer 1 having the above-described structure has a diaphragm 7 on its surface on the pressure generating chamber side with the spacer 1 interposed therebetween.
On the other surface, a nozzle plate 8 is sandwiched in a sandwich shape and fixed integrally.

The vibrating plate 7 has a vibrating region formed as a thin portion 7a and a thick portion 7b for efficiently transmitting the vibration of the piezoelectric vibrator 9 to the entire pressure generating chamber. The tip of the piezoelectric vibrator 9 in the longitudinal vibration mode is fixed to the portion 7b. Reference numeral 10 in the drawing denotes a protective film made of a silicon dioxide film of a silicon single crystal substrate constituting the spacer 1.

In this embodiment, when a drive signal for extending the piezoelectric vibrator 9 is applied, the vibration plate 7
And the pressure generating chamber 2 is contracted. This allows
The ink in the pressure generating chamber 2 is pressurized and ejected as ink droplets from the nozzle openings 5 via the nozzle communication holes 6.

Since the pressure generating chamber 2 has a depth D smaller than the thickness W of the spacer 1, the pressure generating chamber 2 has a small volume, and the rigidity of the base material constituting the spacer 1 can be sufficiently utilized by that amount. It will have great rigidity. Therefore, the piezoelectric vibrator 9 which is applied with a small amount of displacement and shockingly
Of the pressure generating chamber 2 is suppressed and absorption by the ink is suppressed, and the displacement is efficiently converted due to a change in the volume of the pressure generating chamber 2. Make sure to discharge.

As a result, dots having a small diameter can be formed on the recording paper, and since the volume of the pressure generating chamber is small, it can follow the piezoelectric vibrator in the vertical vibration mode which can be driven at a high speed, and can discharge ink droplets. Becomes higher.
Therefore, a plurality of ink droplets can be ejected to the same location in accordance with the density of the image signal, and printing can be performed with area gradation.

Further, since the depth D of the pressure generating chamber 2 is smaller than the thickness of the spacer 1, the overall strength is higher than when the pressure generating chamber 2 is formed as a through hole.
It is possible to prevent deformation of the entire head, which tends to occur in the past even when the piezoelectric vibrator 9 expands and contracts, and to improve the print quality by landing ink droplets on recording paper with high positional accuracy.

Next, a method of manufacturing the above-described recording head will be described. In FIG. 3, reference numeral 11 denotes a silicon single crystal substrate having a crystal orientation (110) on the surface and having a thickness that can be easily handled in the assembling process, for example, 220 μm. Is 1000 ° C in an oxygen atmosphere containing water vapor
The silicon dioxide film (SiO 2) 12 is formed by a thermal oxidation method or the like for about 4 hours so that the silicon dioxide film (SiO 2) 12 functions as a protective film in an etching step described later, for example, 1 μm.
m (FIG. 3 (I)).

A resist layer is provided by exposing and developing a pattern corresponding to the shape of the opening of the common ink chamber at a position to be the common ink chamber 4, and etching is performed by using a silicon oxide etching solution, for example, a buffered hydrofluoric acid solution. The silicon dioxide film 12 in a region other than the resist layer is removed to form windows 13 and 14 which become the common ink chamber 4 (FIG. 3 (II)).

Next, the substrate 11 is immersed in an aqueous solution of KOH maintained at a temperature of 80 ° C. at a concentration of about 25 wt%.
Thus, windows 13 and 14 from which silicon dioxide film 11 has been removed.
, Anisotropic etching is started from both sides. When the etching penetrates through the substrate 1 in this manner, the formation of the through-hole 15 which becomes the common ink chamber 4 is completed (FIG. 3 (II)
I)).

Next, the pressure generating chamber 2 and the ink supply port 3
The silicon dioxide film 12 is removed on one surface of the region to be formed as described above to form the window 16 (FIG. 3 (IV)), and anisotropic etching is performed using the same silicon oxide etchant as described above. .

In this case, since the etching proceeds only from one surface, the etching is stopped when the etching reaches a predetermined depth D, so that the pressure generating chamber 2,
In addition, a concave portion 17 having an opening area and a depth D necessary for the ink supply port 3 can be formed (FIG. 3 (V)).

A copper ion laser beam L is applied to a region 17a of the concave portion 17 serving as the pressure generating chamber 2 on the side opposite to the through hole 15 serving as a common ink chamber (FIG. 4I). As a result, the silicon single crystal substrate 11 and the silicon dioxide film 12 in this portion are evaporated and removed, and a small-diameter through hole 18 required as the nozzle communication hole 6 is formed (FIG. 4 (II)).

At the stage when the spacer is completed in this way, the diaphragm 7 is adhered by connecting the vibration plate 7 to the opening surface of the concave portion 17 and the nozzle opening 5 to the nozzle communication hole 18 on the other surface (FIG. 4). (III)) Further, by attaching the piezoelectric vibrator 9, the recording head is completed. Of course, a thickness 220 enough to develop strength that is easy to handle.
Since the spacer is constituted by the silicon single crystal substrate 11 having a thickness of not less than μm, bending or breaking when bonding the vibration plate 7 and the nozzle plate 8 which is likely to occur when manufacturing a head having a high recording density is possible. Is prevented.

In order to improve the affinity for ink in the flow path and the durability, the existing silicon dioxide film 12 is removed, and a silicon dioxide film is formed on the front surface again by a thermal oxidation method. May be.

In the above embodiment, the nozzle communication hole is formed by laser light processing after the etching process. However, after the nozzle communication hole is formed in the silicon single crystal substrate, the nozzle communication hole is formed.
The through-hole which becomes the common ink chamber 4 by the full etching described above, and the pressure generation chamber 2 by the half etching,
A concave portion serving as the ink supply port 3 may be formed.

In the above-described embodiment, the through holes are formed by irradiating the laser beam from the concave side which becomes the pressure generating chamber. However, the laser beam is radiated from the surface side where the nozzle plate is provided. It may be.

[0035]

As described above, in the present invention, the pressure generating chamber is formed by half etching of a silicon single crystal substrate, the common ink chamber is formed by full etching, and the nozzle communication hole is penetrated by laser processing. Since the nozzle communication hole is formed as a hole, the nozzle communication hole is not limited by the thickness of the substrate, and can be formed as a cylindrical through hole which is smoother than anisotropic etching and is desirable as a flow path. In addition to being able to cope with the high-density arrangement of the openings, it is possible to prevent breakage during the assembling process, and further to prevent deformation of the head during driving, thereby improving the printing quality.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of an ink jet recording head of the present invention by a cross-sectional structure near a pressure generating chamber.

FIG. 2 is a top view showing the structure of the spacer with the diaphragm of the recording head removed.

FIGS. 3 (I) to 3 (V) are views showing the first half of a method of manufacturing a recording head according to the first embodiment; FIGS.

FIGS. 4A to 4C are diagrams showing the latter half of the method of manufacturing the recording head, respectively.

FIG. 5 is a diagram showing an example of a through hole formed by anisotropic etching.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spacer consisting of a silicon single crystal substrate 2 Pressure generating chamber 3 Ink supply port 4 Common ink chamber 5 Nozzle opening 6 Nozzle communication hole 7 Vibration plate 8 Nozzle plate 9 Piezoelectric vibrator

Claims (3)

(57) [Claims] 1. A silicon single crystal silicon substrate to etching resistant layer is formed on one surface with a durable etching solution used for anisotropic etching of a single crystal, the pressure generating chamber by anisotropic etching, the common The ink chamber, and
Ink supply port that connects the pressure generation chamber and the common ink chamber
A spacer, a nozzle plate having nozzle openings formed on one surface of the spacer at a pitch corresponding to the pressure generating chamber, and vibration for expanding and contracting the pressure generating chamber on the other surface of the spacer. In the ink jet recording head provided with a plate, the pressure generation chamber is formed as a concave portion by half-etching the silicon single crystal substrate, the common ink chamber is formed as a through hole by full etching, and the pressure generation chamber is further formed.
An ink jet recording head in which a nozzle communication hole connecting a chamber and the nozzle opening is formed as a through hole by laser processing. 2. A step of forming a window serving as a common ink chamber on both sides of a silicon single crystal substrate to form a through hole by anisotropic etching; and forming a pressure generating chamber on one surface of the silicon single crystal substrate. forming a recess by anisotropic etching to form a window made of concave serving as the pressure generating chamber, it and the common ink chamber
That a step of forming a through hole by laser processing in the region opposite to the through hole, the diaphragm surface of the opening side of the recess, a step of fixing the nozzle plate on the other side, the ink jet recording consisting of Head manufacturing method. 3. A step of forming a through hole by laser processing at a position facing a nozzle opening of a silicon single crystal substrate, and forming a window serving as a common ink chamber on both surfaces of the silicon single crystal substrate to provide anisotropic Forming a through hole by etching; forming a window serving as a pressure generating chamber on one surface of the silicon single crystal substrate to form a recess by anisotropic etching; and forming a recess on the opening side of the recess. Fixing the diaphragm to the nozzle plate on the other surface, and a method for manufacturing an ink jet recording head.