JP2003072072A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent lowering of yield caused by a leak between adjacent channels by reducing a deflection of ink channels brought about in an adhesion assembly process as a result of a difference of coefficients of thermal expansion of a chamber plate and a diaphragm and setting a support part, thereby improving the adhesion at an assembly time. SOLUTION: The diaphragm is comprised of a thin adhesive layer between an iron nickel alloy having a coefficient of thermal expansion extremely close to that of silicon and an aramid resin. Moreover, the ink channel side in touch with ink is formed of a highly chemically resistant aramid resin, and the iron nickel alloy side is etched to be annular for each channel to form an island- shaped projecting part and the support part for surrounding the projecting part. Highly accurate assembling is thus enabled. In addition, an outer periphery etched into the ring shape, that is, the support part is made smaller in the size than the width of a wall face for forming the channel. The adhesion at the assembly time is improved and the yield decrease due to the leak between adjacent channels can be prevented accordingly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-demand type multi-nozzle ink jet head having a plurality of nozzles.

[0002]

2. Description of the Related Art Ink jet print heads according to the prior art include various materials and processing methods such as etching processing of stainless steel, exposure and development of photosensitive resin, punching of ceramic green sheets, etc. Means have been proposed.

However, recently, as the precision and integration of heads have increased, chamber plates made by using anisotropic etching of silicon wafers and dry etching techniques have been announced at academic conferences and the like. . For example, when processing by anisotropic etching, a wafer having a <110> plane orientation is used to make the wall surface of each ink chamber perpendicular to the bottom surface, and a good processing accuracy of ± 2 μm or less can be obtained. . The ink flow path is completed by attaching the vibration plate to the chamber plate that has been processed with high precision in this way.

An example of this diaphragm is Japanese Patent Laid-Open No. 5-2291.
As disclosed in Japanese Patent Publication No. 14, there is a method in which a silicon wafer made of the same material as the chamber plate is thinly processed and electrically bonded for use.

Further, as disclosed in Japanese Patent Application Laid-Open No. 7-276627, a composite film obtained by laminating a resin film and a metal or the like is used as a diaphragm, and a piezoelectric element or the like is used.
In some cases, island-shaped protrusions are provided in the portion where an actuator that vibrates the diaphragm is attached to provide a structure that alleviates characteristic variations due to displacement of the piezoelectric element.

[0006]

When a silicon wafer is used as the vibrating plate, the chamber plate and the vibrating plate are made of the same material, and therefore have the same coefficient of thermal expansion. Does not occur. However, since it is used as a diaphragm and is processed to be extremely thin, it is vulnerable to an impact when the print head is assembled, and since fine processing is performed therein, it is difficult to control the thickness of the diaphragm.
Furthermore, if electrical bonding is not successful due to crystal voids on the silicon surface, ink leakage may occur between adjacent channels.

When a composite film of a resin film and a metal or the like is used as a vibrating plate, when the resin, the metal and the silicon are heat-bonded, if the coefficient of thermal expansion is largely different, the parts are warped. Further, when the chamber plate and the vibration plate are attached to each other with an adhesive or the like, the island-shaped protrusions may interfere and the mounting positions of the chamber plate and the vibration plate may be displaced, or the distribution of adhesion may occur. .

[0008]

In order to solve the above problems, in the present invention, a pressurizing chamber for storing ink, a restrictor for preventing ink flow and backflow, and an electric signal applied to the pressurizing chamber. A piezoelectric element that generates pressure fluctuations,
A diaphragm that forms at least a part of the wall of the pressurizing chamber and the restrictor and is connected to the piezoelectric element with an elastic material, a common ink supply path that supplies ink to the restrictor, and an ink droplet. In an on-demand type multi-nozzle inkjet head composed of an orifice for ejecting from a pressure chamber, a piezoelectric element fixing plate that fixes the piezoelectric element, and a plurality of nozzles that communicate with the pressure chamber and discharge ink. The vibrating plate is one in which the piezoelectric element is joined by an elastic body, and includes an island-shaped projection formed on one surface by etching, and a support section surrounding the projection, and the support section The width of the nozzle in the nozzle arrangement direction is wider than the wall width of the pressurizing chamber.

The diaphragm and the chamber plate forming the pressurizing chamber and the restrictor have substantially the same coefficient of thermal expansion.

Further, the chamber plate is made of silicon single crystal.

Further, the vibrating plate has a three-layer structure of an aramid resin, a thermosetting adhesive and an iron-nickel alloy.

Further, the vibrating plate is bonded to the chamber plate with a thermosetting adhesive.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the configuration of an inkjet head according to an example of the present invention. FIG. 2 is a diagram showing a configuration of an inkjet head in an example of the present invention.
3 is a sectional view taken along line AA ′ in FIG.

This head can perform recording by ejecting ink according to an input signal. 1 is an orifice plate, 2 is an orifice, 3 is a chamber plate, 4 is a common ink passage, 5 is a restrictor, 6 is a pressure chamber, 7 is a housing, 8 is a piezoelectric element, 9 is a piezoelectric element fixing plate, and 10-1. Is a diaphragm island projection, 10-2 is a diaphragm support, 10-3 is a diaphragm base, and 10 is 10-
It is a diaphragm composed of 1, 2, and 3. Further, the respective parts are adhered to each other using an adhesive (not shown). In this example, an epoxy adhesive having high ink resistance was used.

The common ink passage 4, the restrictor 5 and the pressure chamber 6 are filled with ink. By applying a voltage to the piezoelectric element 8 to expand and contract, the ink in the pressurizing chamber is pressed through the vibration plate 10 connected to the piezoelectric element 8. The pressurized ink flows from the upstream to the downstream in the order of the common ink passage 4, the restrictor 5, and the pressure chamber 6, and is ejected from the orifice 2.

In this example, the chamber plate 3 is made of a silicon wafer and is processed by etching with high precision. The piezoelectric element fixing plate 9 is a ceramic,
Made from an insulator such as polyimide. The orifice plate 1 is made of nickel material, stainless steel, and iron-nickel alloy, and the orifice is formed by precision press working.

FIG. 3 is a plan view of a diaphragm according to an example of the present invention. The diaphragm 10 is composed of an iron-nickel alloy having a coefficient of thermal expansion extremely close to that of silicon, an aramid resin, and a thin adhesive layer between them. The ink flow path side that comes into contact with the ink is the diaphragm base material 10-3 made of aramid resin having high chemical resistance,
The iron-nickel alloy side is ring-shaped etched for each channel to form an island-shaped protrusion 10-1 and a support portion 10-2 surrounding it.

Etching of the iron-nickel alloy surface of the diaphragm requires high-precision etching control, and it is produced by the spray type wet etching method used when producing a semiconductor lead frame or the like. The verticality of the etching wall surface can be obtained by pressing the etching liquid with a spray and spraying it onto the etching surface. Further, since the etching is performed on one side, the etching surface is made to be on the lower side and the etching solution is sprayed from the lower side to prevent the etching solution from staying on the etching surface and generating etching distribution.

FIG. 4 is a diagram showing the relationship between the nickel content and the coefficient of thermal expansion in an iron-nickel alloy. In the present invention, the nickel content is set within the range of 8% to 44%, and the thermal expansion coefficient is adjusted within the range of 1 × 10 ⁻⁶ / ° C. to 4 × 10 ⁻⁶ / ° C. The nickel content of the iron-nickel alloy currently used as the standard material is 36 ± 2%, 38 ±
There are 3 types, 2% and 42 ± 2%, and the nickel content is 3
The standard coefficient of thermal expansion is 1 × 10 ⁻⁶ / ° C. at ⁶ % and 4 × 10 ⁻⁶ / ° C. at 42%. On the other hand, the coefficient of thermal expansion of the chamber 3 made of silicon is about 2.6 × 10 ⁻⁶ / ° C., although there is a slight difference depending on the crystal orientation. The coefficient of thermal expansion of the silicon chamber 3 used in this example was 2.8 × 10 ⁻⁶ / ° C. Therefore,
The nickel content of the iron-nickel alloy used for the diaphragm 10 was set to 38%. Moreover, the coefficient of thermal expansion of aramid used as the diaphragm base material 10-3 is about 2 × 10 ^−6.
/ ° C. In addition, in FIG. 4, the shape of the island-shaped protrusions is shown as a rectangle, but the shape is not limited to this.

FIG. 5 shows an example in which the ink jet head is assembled by using materials having greatly different coefficients of thermal expansion, and the displacement of the chamber plate 3 and the diaphragm 10 in the nozzle arrangement direction occurs. The diaphragm base material 10-3 has a coefficient of thermal expansion of about 20.
× 10 -6 ^/ ℃, the metal portion constituting the support portion and the island-shaped protrusions used was the about 18 × 10 -6 ^/ ℃ thermal expansion coefficient. In this way, when the positional displacement between the chamber plate 3 and the vibrating plate 10, particularly the positional displacement in the nozzle array direction occurs,
Since the amount of deformation of the vibrating plate 10 that deforms due to expansion and contraction of the piezoelectric element 8 changes, the amount of pressure change in the pressurizing chamber 6 changes, and the flight speed of ink drops and the amount of ink drops change. Therefore, variations in ink characteristics occur among nozzles, leading to a reduction in product yield.

FIG. 6 shows the chamber plate 3 in this example.
2 is a result of measuring the positional relationship between the chamber plate 3 and the diaphragm 10 when the diaphragm 10 and the diaphragm 10 are used. By using the method of this example, it is possible to solve the problem of positional deviation and obtain uniform and excellent characteristics. Further, by using a material having a similar coefficient of thermal expansion, the amount of warpage during plate bonding could be suppressed to 2 μm or less.

In this example, the island-shaped protrusion and the support portion surrounding the island-shaped protrusion are formed. Even if the piezoelectric element 8 and the diaphragm 10 are misaligned, the island-shaped protrusion 10-1 can stably transfer the energy due to the expansion and contraction of the piezoelectric element 8 to the diaphragm 10.

When aligning each component, each component is provided with a positioning hole to perform highly accurate positioning by using a positioning pin. When the aramid resin or the like used in this example is used as the vibration plate base material 10-3, the strength of the positioning hole is insufficient, so etching is performed by leaving the metal part around the positioning hole and maintaining the strength by the metal part. Is done.

FIG. 7 shows an example in which the ring-shaped etched outer periphery (that is, the support portion 10-2) is not provided. In this case, the metal portion around the positioning hole serves as a spacer, and the pressure is not properly applied to the portion where the upper wall surface of the chamber plate 3 and the vibration plate 10 are adhered to each other, resulting in adhesion failure and leakage between adjacent channels. May occur. Further, although this problem can be mitigated by subjecting the bonding jig to microfabrication, it is necessary to control the depth of microfabrication.

In the present invention, as shown in FIG. 8, even if a metal portion is left around the positioning hole, the support portion 10-
Since 2 is provided, a uniform and good pressure can be applied to the entire plate bonded portion when the upper wall surface of the chamber plate 3 and the diaphragm 10 are bonded.

When the head is assembled, the positional relationship between the chamber plate 3 and the vibrating plate 10 may be displaced as a whole due to variations in the jig used for the assembly or variations in the head parts. In this case, pressure may be biased when the upper wall surface of the chamber plate 3 and the vibrating plate 10 are bonded to each other, resulting in defective bonding and leakage between adjacent channels.

In the present invention, as shown in FIG. 2, the adhesiveness at the time of assembling is set by "the width W1 between the vibration plate support portions 10-2 <the width W2 of the ink flow path of the chamber plate 3". It is possible to improve and prevent a decrease in yield due to leakage between adjacent channels.

A specific example of the above W1 <W2 will be described. The displacement between the diaphragm support and the chamber plate is caused by A. Positioning hole portion, B. Pitch error of channel part, C.I. There are three possible causes of thermal expansion. As for the current precision of the diaphragm support part, an error of ± 5 μm from the etching precision with respect to A and an error of ± 10 μm with respect to B due to the same reason of ± 5 μm occur. Although C varies depending on the assembling method and cannot be specified, it can be resolved by making the coefficient of thermal expansion match that of the silicon chamber. Therefore, the maximum is ± 15 μm in A to C (the influence of C is ± 5
error (in μm).

In the case of 100 npi (nozzle / inch), the chamber plate ink channel width W2 is 150 μm.
m. Considering the error, W2 is 150 ± 15μm
Therefore, the minimum value of W2 is 135 μm. Therefore, by setting the error of W1 to 120 μm, which is a value not exceeding 135 μm at the maximum, it is possible to prevent leakage between adjacent channels due to processing variations. Similarly, in the case of 75 npi, W2 is 200
μm, and therefore W1 may be 170 μm.

In terms of ratio, in the case of 100 npi: 120 (μm) / 150 (μm)
= 0.80 75 npi: 170 (μm) / 200 (μm)
= 0.85, and in this example, W1 is approximately 0.8 to W2.
It should be 0.85.

In the case of the diaphragm provided with the support portion 10-2 as described above, it is conceivable that the deflection amount of the diaphragm may be reduced. That is, even if the same energy is applied to the piezoelectric element 8, there is a possibility that the ink droplet amount and the ink droplet flight speed may change as compared with those without the support portion. In this case, there is no problem because the problem can be solved by changing the thickness of the diaphragm base member 10-3 to control the characteristic relating to the deflection amount of the diaphragm.

[0032]

According to the present invention, the chamber plate is made with high precision using a silicon wafer. The diaphragm consists of a thin adhesive layer between the iron-nickel alloy and the aramid resin, which have a coefficient of thermal expansion very close to that of silicon, and the ink flow path side that comes into contact with the ink is made of aramid resin with high chemical resistance, and the iron-nickel alloy side. By etching each channel in a ring shape to form island-shaped protrusions and support portions surrounding the island-shaped protrusions, highly accurate assembly can be performed. In addition, the size of the ring-shaped outer periphery, that is, the support portion, is smaller than the width of the wall surface forming the flow path, which improves the adhesiveness during assembly and reduces the yield due to leakage between adjacent channels. Can be prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an inkjet head used in the present invention.

FIG. 2 is a cross-sectional view of a portion of FIG. 1A-A showing a configuration of an inkjet head used in the present invention.

FIG. 3 is a plan view of a diaphragm used in the present invention.

FIG. 4 is a diagram showing a relationship between a nickel content and a coefficient of thermal expansion in an iron-nickel alloy.

FIG. 5 is a diagram showing a misaligned state when materials having greatly different coefficients of thermal expansion are used.

FIG. 6 is a diagram showing a misaligned state when a material having a similar coefficient of thermal expansion is used in the present invention.

FIG. 7 is a diagram showing an example in which a support part is not provided.

FIG. 8 is a view showing an example used in the present invention, in which a support portion is not provided.

[Explanation of symbols]

1 is an orifice plate, 2 is an orifice, 3 is a chamber plate, 4 is a common ink passage, 5 is a restrictor,
Reference numeral 6 is a pressurizing chamber, 7 is a housing, 8 is a piezoelectric element, 9 is a piezoelectric element fixing plate, 10-1 is a diaphragm island projection, 10-2 is a diaphragm support, and 10-3 is a diaphragm base material. Part, 10 is 1
A diaphragm consisting of 0-1, 2, and 3, 11 is a bonding jig, and 12
Is a positioning pin, 13 is a positioning hole

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Jun Nagata             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. F-term (reference) 2C057 AF40 AG44 AG53 AG55 AP25                       AP33 AP77 AQ02 BA03 BA14

Claims (5)

[Claims] 1. A pressurizing chamber for storing ink, a restrictor for preventing ink flow and backflow, a piezoelectric element for generating pressure fluctuation in the pressurizing chamber by applying an electric signal, the pressurizing chamber and wrist. A diaphragm that forms at least a part of the wall surface of the restrictor and is connected to the piezoelectric element with an elastic material, a common ink supply path that supplies ink to the restrictor, and an ink droplet is ejected from the pressure chamber. In the on-demand type multi-nozzle inkjet head including an orifice, a piezoelectric element fixing plate that fixes the piezoelectric element, and a plurality of nozzles that communicate with the pressure chamber and eject ink, the vibrating plate is The piezoelectric element is joined by an elastic body, and is composed of an island-shaped protrusion formed on one surface by etching, and a support portion surrounding the protrusion. The nozzle arrangement direction of the width of the support portion, the ink jet print head, characterized in that wider than the wall width of the pressurizing chamber. 2. The ink jet print head according to claim 1, wherein the vibrating plate and the chamber plate forming the pressurizing chamber and the restrictor have substantially the same coefficient of thermal expansion. 3. The ink jet print head according to claim 1, wherein the chamber plate is made of silicon single crystal. 4. The ink jet print head according to claim 3, wherein the diaphragm has a three-layer structure of an aramid resin, a thermosetting adhesive, and an iron-nickel alloy. 5. The ink jet print head according to claim 1, wherein the vibration plate is adhered to the chamber plate with a thermosetting adhesive.