JPH06305156A - Liquid droplet jet device - Google Patents

Abstract

PURPOSE:To always stably inject ink droplets when the walls of ink passages are deformed to inject ink droplets by using an adhesive whose Young's modulus is a specific value or less when a nozzle plate having nozzles communicating with ink passages formed thereto to the end part of a passage member having ink passages formed thereto. CONSTITUTION:Many grooves 8 are formed to a piezoelectric ceramics plate 2 and the upper surfaces of the grooves 8 are covered with a cover plate 3 to form many ink passages. A nozzle plate 31 having nozzles 32 at the positions corresponding to the ink passages is bonded to the end surfaces of both of the piezoelectric ceramics plate 2 and the cover plate 3 by an adhesive. This adhesive is characterized by that the value obtained by dividing the Young's modulus of the adhesive after curing by the thickness of the adhesive layer is 1X10<6>kg/mm<3> or less, pref., 5X10<5>kg/mm<2> or less, more pref., 3X10<5>kg/mm<3> or less. By this constitution, the sufficient volumetric change of ink passages is obtained by the deformation of the walls 11 of the ink passages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet ejection device.

[0002]

2. Description of the Related Art Conventionally, as a droplet ejecting apparatus using a piezoelectric ceramic element, for example, a drop-on-demand type droplet ejecting apparatus has been proposed. This is one in which the volume in the ink flow path is changed, the ink in the ink flow path is ejected from the nozzle when the volume decreases, and the ink is introduced into the ink flow path from the ink supply port when the volume increases. Is. Then, a desired character or image is formed by ejecting ink from the ejecting device at a predetermined position according to the print data.

As such a liquid droplet ejecting apparatus, for example, Japanese Patent Laid-Open Nos. 63-247051 and 63-252.
750 and JP-A-2-150355. The schematic configuration of the droplet ejecting device will be described below.

As shown in FIG. 3, the ink jet printer head 1 is composed of a piezoelectric ceramic plate 2, a cover plate 3, a nozzle plate 31, and a substrate 41.

The piezoelectric ceramic plate 2 is provided with a plurality of grooves 8 cut by a thin disk-shaped diamond blade or the like. Further, the side wall 11 which is the side surface of the groove 8 is polarized in the direction of arrow 5. The grooves 8 are of the same depth and are parallel. The depths of the grooves 8 gradually become shallower as they approach the one end face 15 of the piezoelectric ceramic plate 2, and a shallow groove 16 is formed near the one end face 15. Then, on the inner surface of the groove 8,
Metal electrodes 13 are formed on the upper half of both side surfaces by sputtering or the like. Also, on the inner surface of the shallow groove 16,
A metal electrode 9 is formed on the side surface and the bottom surface by sputtering or the like. As a result, the metal electrodes 13 formed on both sides of the groove 8 are separated from the metal electrodes 9 formed on the shallow groove 16.
Are linked by.

Next, the cover plate 3 is made of a ceramic material, a resin material, or the like. Then, the cover plate 3 is formed by grinding or cutting.
An ink inlet 21 and a manifold 22 are formed. Then, the surface of the piezoelectric ceramic plate 2 on the side where the groove 8 is processed and the surface of the cover plate 3 on the side where the manifold 22 is processed are adhered by an adhesive 4 such as an epoxy adhesive 4 (see FIG. 6). Therefore, the ink jet printer head 1 is formed with a plurality of ink flow paths 12 (FIG. 6) which cover the upper surfaces of the grooves 8 and are laterally spaced from each other. As shown in FIG. 6, the ink flow path 12 has an elongated shape with a rectangular cross section, and all the ink flow paths 12 are filled with ink.

As shown in FIG. 3, the ink flow paths 1 are formed on the end faces of the piezoelectric ceramic plate 2 and the cover plate 3.
The nozzle plate 31 provided with the nozzle 32 at a position corresponding to the position 2 is adhered by an adhesive 33 (see FIG. 4) such as epoxy. This nozzle plate 31
Is formed of a plastic such as polyalkylene (for example, ethylene) terephthalate, polyimide, polyetherimide, polyetherketone, polyethersulfone, polycarbonate, or cellulose acetate.

A substrate 41 is adhered to the surface of the piezoelectric ceramic plate 2 opposite to the processed side of the groove 8 with an adhesive (not shown) such as an epoxy type. A pattern 42 of a conductive layer is formed on the substrate 41 at positions corresponding to the positions of the ink flow paths 12. The pattern 42 of the conductive layer and the metal electrode 9 on the bottom surface of the shallow groove 16 are connected by a conductive wire 43 by known wire bonding or the like.

Next, the configuration of the control unit will be described with reference to FIG. 5, which is a block diagram of the control unit. The conductive layer patterns 42 formed on the substrate 41 are individually connected to the LSI chip 51. The clock line 52, the data line 53, the voltage line 54, and the ground line 55 are also LS.
It is connected to the I-chip 51. The LSI chip 51 is
Based on the continuous clock pulse supplied from the clock line 52, it is determined from which nozzle 32 the ink droplet should be ejected according to the data appearing on the data line 53. Then, the voltage V of the voltage line 54 is applied to the pattern 42 of the conductive layer that is electrically connected to the metal electrode 13 in the driven ink flow path 12. Further, the voltage 0V of the ground line 55 is applied to the pattern 42 of the conductive layer which is electrically connected to the metal electrode 13 other than the driven ink flow path 12.

Next, the operation of the ink jet printer head 1 will be described with reference to FIGS. LSI chip 5
1 determines that the ink is to be ejected from the ink flow path 12b of the inkjet printer head 1 according to the required data. Then, the positive drive voltage V is applied to the metal electrodes 13e and 13f, and the metal electrodes 13d and 13g are grounded. As shown in FIG. 6, an arrow 14 is formed on the side wall 11b.
A driving electric field in the direction of b is generated, and an arrow 14 is formed on the sidewall 11c.
A driving electric field in the direction of c is generated. Then, since the driving electric field directions 14b and 14c are orthogonal to the polarization direction 5,
The side walls 11b and 11c have a piezoelectric thickness sliding effect,
In this case, the ink flow path 12b is rapidly deformed inward. Due to this deformation, the volume of the ink flow path 12b is reduced, the ink pressure is rapidly increased, a pressure wave is generated, and an ink droplet is ejected from the nozzle 32 (FIG. 3) communicating with the ink flow path 12b.

When the application of the driving voltage V is stopped,
Since the side walls 11b and 11c gradually return to the positions before deformation (see FIG. 5), the ink pressure in the ink flow path 12b gradually decreases. Then, ink is supplied from the ink supply port 21 (FIG. 6) through the manifold 22 (FIG. 6) into the ink flow path 12b.

[0012]

However, in the above-mentioned conventional liquid droplet ejecting apparatus, since the side wall 11 is deformed by the piezoelectric thickness sliding effect, the volume of the ink flow passage 12 is changed to eject the ink droplet. Sufficient ink flow path 12
Requires a volume change of. For this purpose, the elasticity of the adhesive 33 that bonds the nozzle plate 31 and the piezoelectric ceramic plate 2 and the cover plate 3 in FIG. 4 becomes a problem. That is, when the elasticity of the adhesive 33 is small, that is, the rigidity is large, the end surface of the side wall 11 and the nozzle plate 31 are
Are fixed, and the change in the deposition of the ink flow path 12 due to the piezoelectric thickness sliding effect of the side wall 11 is not sufficiently performed, which affects the ejection of ink droplets and a desired ejection speed of ink droplets cannot be obtained. There was a problem that ink droplets did not eject.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a droplet ejecting apparatus which can always eject ink droplets stably.

[0014]

To achieve this object, according to the present invention, a flow path member having an ink flow path whose end is opened and an end portion of the flow path member are bonded with an adhesive. A nozzle plate having nozzles formed so as to communicate with the ink flow path, the volume of the ink flow path is changed by deformation of the wall of the ink flow path, and the ink flow path is filled with the ink flow path. In a droplet ejecting device that ejects ink, a value obtained by dividing the Young's modulus of an adhesive agent for adhering the nozzle plate by the thickness of the adhesive layer of the adhesive agent is 1 × 10 5.
It is characterized by being ⁶ kg / mm ³ or less.

In the second aspect, a value obtained by dividing the Young's modulus of the adhesive by the thickness of the adhesive layer is 5 × 10 ^5.
It is characterized by being less than kg / mm ³ .

Further, in claim 3, the value obtained by dividing the Young's modulus of the adhesive by the thickness of the adhesive layer is 3 × 10 ⁵ kg /
It is characterized by being less than or equal to mm ³ .

[0017]

In the droplet jetting apparatus of the present invention having the above-mentioned structure, the Young's modulus of the adhesive for adhering the nozzle plate divided by the thickness of the adhesive layer of the adhesive is 1 × 10 ^6.
By setting the pressure to be not more than kg / mm ³ , a predetermined elasticity can be obtained in the adhesive layer, and a predetermined change amount can be obtained in the volume change of the ink flow path due to the deformation of the wall.

[0018]

The present invention will be described in detail below with reference to the drawings. For the sake of convenience, the same parts as those of the conventional example and the equivalent parts are designated by the same reference numerals, and detailed description thereof will be omitted.

The adhesive 4 for bonding the upper surface of the side wall 11 of the piezoelectric ceramic plate 2 and the cover plate 3 will be described. As described above, if the Young's modulus of the adhesive 4 is small, or the adhesive layer of the adhesive 4 is thick, and the elasticity of the adhesive layer of the adhesive 4 is large, that is, the rigidity is small, as shown in FIG. Since the adhesive 4 is deformed in the direction opposite to the direction in which the side wall 11 is deformed, a sufficient volume change of the ink flow path 12 cannot be obtained.

Therefore, the ink droplet ejection experiment of the ink jet printer head 1 was conducted for each of the epoxy adhesives 4 having different Young's moduli (after curing), by changing the thickness of the adhesive layer. The Young's modulus after curing is important for the adhesive 4 used in the experiment, and other properties may not be considered in this experiment. The result of the experiment is shown in FIG. The thickness of the adhesive layer of the adhesive 4 in the experiment was measured with a microscope. Inkjet printer head 1
Since the ejection speed of the ink droplets is proportional to the volume change of the ink flow passage 12, the ejection speed of the ink droplets was measured and evaluated.

Here, the ejection speed of ink droplets and the stability of ink ejection will be described based on experimental experience. First, when the ejection speed is less than 1 m / s, the ink is not ejected (ink droplets are not separated), or even if it is ejected, the ink is ejected at a desired position due to the influence of the air flow between the nozzle 32 and the paper. Drops do not adhere and print quality deteriorates. Therefore, in order to commercialize the liquid droplet ejection device, the ejection speed must be at least 1 m / s or more.

Further, the influence of the ink jetting speed on the droplet jetting device is as follows. First, when the nozzle shape is non-uniform or dust or ink adheres to the vicinity of the nozzle, the straightness of the ink is affected if the ejection speed is low. Further, in the carriage scanning type liquid droplet ejecting apparatus, the air flow between the nozzle 32 and the paper becomes strong due to the movement of the carriage, and when the ejection speed is low, the ink landing point is likely to be displaced. This is more prominent when the carriage movement speed is increased for high-speed printing or when the distance between the nozzle and the platen is increased so that printing can be performed on thick paper.

Therefore, in consideration of some of the above conditions, the injection speed is preferably 3 m / s or more and the injection speed is 5 m / s in order to realize stable injection.
If it is above, even if all the above-mentioned conditions are considered, stable injection can be realized.

Based on the above, the evaluation of the ink jet printer head 1 in FIG. 1 is performed by setting the ejection speed of ink droplets to 5 m / s or more, 3 to 5 m / s, and 1 to 3 m / s.
s and less than 1 m / s were evaluated.

As can be seen from FIG. 1, the ejection speed of the ink droplets is 5 m / s or more in the area above the straight line L3, the ejection speed is 3 to 5 m / s in the area between the straight lines L3 and L2, and the straight lines L2 and L1. The injection speed in the region between 1 to 3 m /
In the region below s and the straight line L1, the injection speed is less than 1 m / s. Here, the inclinations of the straight lines L1, L2, and L3 are values obtained by dividing the Young's modulus of the adhesive 4 by the thickness of the adhesive 4,
This value is 5 × 10 ³ kg / mm ³ , 5 × 10 ⁴ kg / mm ³
mm ³ , 1.2 × 10 ⁵ kg / mm ³ . Therefore, the value obtained by dividing the Young's modulus of the adhesive 4 by the thickness of the adhesive 4 is 5 × 1.
0 ³ kg / mm ³ or more, preferably 5 × 10 ⁴ kg / mm ³
As described above, more preferably 1.2 × 10 ⁵ kg / mm ³ or more, stable ink droplet ejection can be performed. Here, from the above results, it is preferable that the thickness of the adhesive layer is thinner, because the rigidity is increased, but it is necessary to have a thickness enough to completely bond the cover plate 3 and the upper surface of the side wall 11, and the adhesive layer is thin. There are also technical limits for doing so. Therefore, when the thickness of the adhesive layer is increased to some extent, an adhesive having a large Young's modulus may be used depending on the required jetting speed.

As described above, the value obtained by dividing the Young's modulus of the adhesive 4 for bonding the upper surface of the side wall 11 of the piezoelectric ceramic plate 2 and the cover plate 3 by the thickness of the adhesive 4 is 5 × 10 ³ kg / mm ³ or more, preferably 5 × 10 ⁴ kg
/ Mm ³ or more, more preferably 1.2 × 10 ⁵ kg / mm
If the material and the thickness of the adhesive are selected so as to be ³ or more, the deformation of the side wall 11 due to the piezoelectric thickness slip effect can sufficiently change the volume of the ink flow path 12, and the stable ink droplet ejection can be performed. Be seen.

Next, the adhesive 33 (see FIG. 4) for bonding the nozzle plate 31 to the end faces of the piezoelectric ceramic plate 2 and the cover plate 3 will be described.

As shown in FIG. 4, the adhesive 33 is attached to the side wall 11
Is formed between the end surface of the piezoelectric ceramics plate 2 including the nozzle plate 31 and the nozzle plate 31, and the adhesive 33 is formed between the ink flow path 12 (FIG. 6) communicating with the nozzle 32 and the nozzle plate 31. Not not. Generally, the nozzle plate 31 is made of a resin or a metal material in consideration of the formation of the nozzles 32, and has a linear expansion coefficient different from that of the piezoelectric ceramic plate 2 made of a ceramic material. Therefore, the piezoelectric ceramic plate 2 and the nozzle plate 3
The adhesive 33 for bonding 1 and 1 needs elasticity to some extent in order to interfere with the difference between the linear expansion coefficient of the piezoelectric ceramic plate 2 and the linear expansion coefficient of the nozzle plate 31.
Further, when the elasticity of the adhesive 33 is small, that is, the rigidity is large, the end face of the side wall 11 and the nozzle plate 31 are fixed, and the volume change of the ink flow path 12 due to the piezoelectric thickness sliding effect of the side wall 11 is sufficiently performed. Without affecting the ejection of ink drops.

Therefore, the ink droplet ejection experiment of the ink jet printer head 1 was performed for each of the epoxy adhesives 33 having different Young's moduli (after curing) by changing the thickness of the adhesive layer. The Young's modulus after curing of the adhesive 33 used in the experiment is important, and other properties may not be considered in this experiment. The inkjet printer head 1 was evaluated by measuring the ejection speed of ink droplets. The ejection speed of the ink droplets is 5 m / s or more, 3 to 5 m / s, and 1 to 3 m / s for the reason described above.
s and less than 1 m / s were evaluated. The thickness of the adhesive 33 was measured with a microscope after cutting the inkjet printer head 1 in the direction of the ink flow path 12 after the ejection test. The result of the experiment is shown in FIG.

As can be seen from FIG. 2, the ejection velocity of the ink drop is 5 m / s or more in the region below the straight line M3, the ejection velocity is 3 to 5 m / s in the region between the straight lines M3 and M2, and the straight lines M2 and M1. The injection speed in the region between 1 to 3 m /
In the region above s and the straight line M1, the injection speed is less than 1 m / s. Here, the inclinations of the straight lines M1, M2, M3 are values obtained by dividing the Young's modulus of the adhesive 33 by the thickness of the adhesive 33, and these values are 1 × 10 ⁶ kg / mm ³ , 5 × 10 in order. ⁵ k
g / mm ³ , 3 × 10 ⁵ kg / mm ³ . Therefore, the value obtained by dividing the Young's modulus of the adhesive 33 by the thickness of the adhesive 33 is 1
× 10 ⁶ kg / mm ³ or less, preferably 5 × 10 ⁵ kg /
If it is less than or equal to mm ³ , and more preferably less than or equal to 3 × 10 ⁵ kg / mm ³ , stable ink droplet ejection can be performed.

As described above, the Young's modulus of the adhesive 33 for bonding the nozzle plate 31 to the end faces of the piezoelectric ceramic plate 2 and the cover plate 3 is 1 × 10 ⁶ kg divided by the thickness of the adhesive 33. / Mm ³ or less, preferably 5 × 10 ⁵ kg / mm ³ or less, more preferably 3 × 10
If the material and the thickness of the adhesive are selected so as to be ⁵ kg / mm ³ or less, the deformation of the side wall 11 due to the piezoelectric thickness slip effect can sufficiently change the volume of the ink flow path 12.
Stable ejection of ink droplets is performed.

Based on the above experimental results, the ink jet printer head 1 of this embodiment was prepared and printing was attempted as a carriage scanning type droplet ejection device.
As the specifications of the droplet ejecting device, the carriage moving speed is 0.635 m / s, and the distance between the nozzle and the paper surface is 1.
It was set to 5 mm.

By the way, when the ink jet printer head 1 is manufactured, the material and the bonding process of the adhesive 4 for bonding the cover plate 3 and the adhesive 33 for bonding the nozzle plate 31 to the piezoelectric ceramic plate 2 are different. Since this leads to waste of manufacturing cost and manufacturing time, in the present embodiment, the adhesives made of the same material are used for the same bonding step. Therefore, since the Young's modulus and the thickness of the adhesive become equal, it is necessary to set the Young's modulus and the thickness so as to satisfy both the above two experimental results. From the above experimental results, the most preferable relation between Young's modulus and thickness is that the value obtained by dividing Young's modulus by thickness is 1.2 × 10 ⁵ kg / mm ³ or more, 3 × 10 ⁵ kg / mm ³
It is the following. Therefore, in this embodiment, the Young's modulus is 730 k.
An adhesive of g / mm ² was used, and the thickness of the adhesive was 3 μm. The value obtained by dividing the Young's modulus in this case by the thickness is 2.43.
Since it is × 10 ⁵ kg / mm ³ , both conditions can be satisfied.

The ink jet printer head 1 thus produced evaluated a print sample when printed as a droplet ejecting device, focusing on the deviation of the ink landing point, and as a result, good printing with almost no deviation. It was confirmed that was done.

In this embodiment, the epoxy adhesive is used, but an acrylic adhesive, a phenol adhesive or the like may be used.

[0036]

As is apparent from the above description, in the droplet ejecting apparatus of the present invention, the Young's modulus of the adhesive agent for adhering the end portion of the flow path member forming the ink flow path and the nozzle plate The value divided by the thickness of the adhesive layer of the adhesive is 1 x 1
Since it is 0 ⁶ kg / mm ³ or less, a sufficient volume change of the ink flow path can be obtained by the deformation of the wall of the ink flow path, and stable ink ejection can be performed.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a Young's modulus of an adhesive agent for adhering a piezoelectric ceramic plate and a cover plate and a thickness of an adhesive layer in an example of the present invention.

FIG. 2 is a graph showing the relationship between the Young's modulus of the adhesive agent for adhering the piezoelectric ceramic plate and the nozzle plate and the thickness of the adhesive layer in the example.

FIG. 3 is a perspective view showing a configuration of the inkjet printer head according to the embodiment and the related art.

FIG. 4 is a cross-sectional view of the ink jet printer head according to the above-described embodiment and the related art, taken along a flow path of an ink flow path.

FIG. 5 is an explanatory diagram showing a control unit of the inkjet printer head according to the embodiment and the prior art.

FIG. 6 is a cross-sectional view showing a configuration of the inkjet printer head according to the embodiment and the related art.

FIG. 7 is an explanatory diagram showing an operating state of the inkjet printer head according to the embodiment and the related art.

FIG. 8 is an explanatory diagram showing a state of an adhesive layer at the time of a piezoelectric thickness slip effect of the side wall when the elasticity of the adhesive layer between the side wall of the inkjet printer head and the cover plate is large.

[Explanation of symbols]

 2 Piezoelectric ceramic plate 11 Side wall 12 Ink flow path 31 Nozzle plate 33 Adhesive

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C09J 9/00 JAP 7415-4J

Claims (3)

[Claims] 1. A flow path member having an ink flow path having an open end, and a nozzle formed so as to communicate with the ink flow path by being bonded to an end of the flow path member with an adhesive. A droplet ejecting apparatus that has a nozzle plate, changes the volume of the ink flow path by deformation of the wall of the ink flow path, and ejects the ink filled in the ink flow path. The value obtained by dividing the Young's modulus of the adhesive to be divided by the thickness of the adhesive layer of the adhesive is 1 × 10 ⁶ kg.
/ Mm ³ or less, a droplet ejecting device. 2. The liquid droplet ejecting apparatus according to claim 1, wherein a value obtained by dividing Young's modulus of the adhesive by the thickness of the adhesive layer is 5 × 10 ⁵ kg / mm ³ or less. 3. The liquid droplet ejecting apparatus according to claim 2, wherein a value obtained by dividing the Young's modulus of the adhesive by the thickness of the adhesive layer is 3 × 10 ⁵ kg / mm ³ or less.