JPH08290570A - Ink jet head - Google Patents

Abstract

PURPOSE: To obtain the excellent print quality by providing a metal layer at least at one connecting part of a nozzle plate and an ink discharge energy generating element. CONSTITUTION: Openings are provided at the positions corresponding to the positions of ink chambers 304 at the end face of a piezoelectric ceramic plate 302 and the end face of a cover plate 320, and a seal plate 340 formed of the ceramic material of lead zirco-titanate is stuck by epoxy adhesive. A metal thin film layer 342 of Au is formed on the stuck surface of the plate 340 to a nozzle plate 1 by a vacuum evaporation method. The layer 342 formed between the plate 1 and the head body improves the bonding strength of the plate 1 to the body. The layer 342 is operated as the thermal strain buffering material generated between the plate 1 and the body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head body which has a nozzle plate having a plurality of nozzles for ejecting ink and an ink chamber communicating with the nozzles and which generates energy in the ink in the ink chamber. And an inkjet head provided with.

[0002]

2. Description of the Related Art Conventionally, as a drop-on-demand type ink jet head, for example, the volume of an ink flow path is changed by deformation of piezoelectric ceramics, and when the volume is reduced, the ink in the ink flow path is ejected as a droplet from a nozzle. In some cases, ink is introduced into the ink flow path from the ink introduction port when the volume is increased. Then, ink droplets are ejected from a nozzle at a required position in accordance with required print data to form a desired character or image on a paper surface facing the inkjet head.

As an ink jet head of this type,
For example, there is one described in JP-A-63-247051. The ink jet head has a plurality of parallel ink flow paths separated by piezoelectric ceramic partitions, one end of the ink flow path communicates with the nozzle of the nozzle plate, and ink is supplied to the other end. By connecting the means, the volume of the ink flow path is changed by the deformation of the partition wall, and the ink is ejected from the nozzle.

As a method for manufacturing the nozzle plate of the ink jet head as described above, for example, JP-A-61-161
As disclosed in Japanese Patent No. 32761, there is known a method of forming nozzles on a film-shaped nozzle plate by an excimer laser beam. In addition, JP-A-3-29
As disclosed in Japanese Patent No. 7651, there is known a method of molding a nozzle plate having nozzles formed by an injection molding method of a polymer resin material.

[0005]

Originally, in the case of a nozzle of an ink jet head, if the volume in the nozzle is small, air is entrained in the ink flow path, good ink ejection cannot be performed, and the printing quality deteriorates. was there.

In the method of forming a nozzle by an excimer laser beam disclosed in the above-mentioned Japanese Patent Laid-Open No. 61-32761, only linear holes can be processed, and the taper angle of the inner surface of the nozzle cannot be made large. Therefore, once the orifice diameter of the nozzle to be formed is determined, only a linear hole having that diameter is formed, and the nozzle volume cannot be increased.

Therefore, according to the method of manufacturing a nozzle plate by injection molding disclosed in Japanese Patent Laid-Open No. 3-297651, the volume inside the nozzle is increased and the entrainment of air is prevented. A good nozzle shape can be easily obtained. For example, in an ink jet head formed by adhering a nozzle plate injection-molded with polysulfone, which is a polymer material, and an actuator plate formed with lead zirconate titanate (PZT), which is piezoelectric ceramics, a linear thermal expansion coefficient of the nozzle plate is used. And the coefficient of linear thermal expansion of the actuator plate are significantly different. When the nozzle plate and the actuator plate are bonded using the epoxy adhesive, the epoxy adhesive is heated and cured at a relatively high temperature. When the inkjet head is exposed to the low temperature side (for example, -40 ° C) of the storage temperature range that should be guaranteed in consideration of transportation of general information equipment, the nozzle plate moves from the actuator plate due to the difference in linear thermal expansion coefficient. May peel off,
There is a problem that the printing quality is poor because the jetting is not performed well.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an ink jet head having excellent printing quality.

[0009]

In order to achieve this object, in a first aspect of the present invention, there is provided a nozzle plate having a plurality of nozzles for ejecting ink, and an ink chamber communicating with the nozzles. In the ink jet head including a head body that applies energy to the ink in the ink chamber, a metal layer is provided on a joint portion of either one or both of the nozzle plate and the ink ejection energy generating element.

According to a second aspect of the present invention, the nozzle plate is formed by an injection molding method, and the head main body is formed of piezoelectric ceramics.

According to a third aspect of the present invention, it is used in an environment of -40 ° C to 80 ° C.

[0012]

In the ink jet head of the present invention having the above structure, the metal layer formed between the nozzle plate and the head body improves the bonding strength between the nozzle plate and the head body. Further, the metal layer acts as a thermal strain buffering material generated between the nozzle plate and the head body.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIGS. 2, 3 and 4, the ink jet head 300 includes a piezoelectric ceramic plate 3
02, cover plate 320, nozzle plate 1, manifold member 301, and seal plate 340.

The piezoelectric ceramic plate 302 is
The piezoelectric ceramic plate 302 is made of a ceramic material such as lead zirconate titanate (PZT).
A plurality of lateral grooves 303 are formed by cutting with a diamond blade or the like. The partition wall 306, which is the side surface of the lateral groove 303, is polarized in the direction of arrow 305. The lateral grooves 303 have the same depth and are parallel to each other, and are machined so as to open on the end surfaces 302a and 302b of the piezoelectric ceramic plate 302 facing each other.

On the end surface 302a of the piezoelectric ceramic plate 302, vertical grooves 311a are formed every other one so as to communicate with the horizontal grooves 303. On the end surface 302b of the piezoelectric ceramic plate 302, vertical grooves 311b are formed every other one so as to communicate with the horizontal grooves 303.
The vertical grooves 311a and 311b are formed alternately, and the vertical groove 311a and the vertical groove 311b are adjacent to each other.
3 is formed. The vertical grooves 311a are provided in the lateral grooves 303 on both outer sides. In addition, the surface 30 of the piezoelectric ceramic plate 302 opposite to the side on which the lateral groove 303 is processed
Patterns 324 and 325 made of a conductive material are formed on 2c.

The piezoelectric ceramic plate 302
The metal electrodes 308, 309, 310 are formed from a vapor deposition source (not shown) such as sputtering, which is arranged at a position obliquely above the groove processed surface and the end surface 302a (FIG. 2).
Is vapor-deposited from the directions of arrows 330a and 330b in FIG. At this time, the end face 302a of the piezoelectric ceramic plate 302 and the zenith of the partition wall 306 are masked so that metal electrodes are not formed. Then, as shown in FIG. 2, the metal electrode 308 is formed in the upper half regions of both side surfaces of the lateral groove 303, and the metal electrode 309 is formed in the vertical groove 311a.
The metal electrode 310 is formed on a part of the side surface and a part of the bottom surface of the lateral groove 303 on which the end surface 302a is not formed.
It is formed on the end surface 302a side of the side surfaces of the vertical groove 311a. The metal electrode 308 and the metal electrode 309 are electrically connected, and the metal electrode 308 and the metal electrode 310 are electrically connected.

Next, metal electrodes 316 and 317 are formed from a vapor deposition source (not shown) such as sputtering, which is arranged obliquely above the surface 302c of the piezoelectric ceramic plate 302 and the end surface 302b (see FIG. 4 is vapor-deposited from the direction of arrows 331a and 331b). still,
Masking is performed so that metal electrodes are not formed in the regions of the end faces 302b and 302c of the piezoelectric ceramic plate 302 where the patterns 324 and 325 are formed. Then, as shown in FIG. 4, the metal electrode 316 is formed on the surface 302 c of the piezoelectric ceramics plate 302 in the vertical groove 3.
A region on the end face 302a side of the bottom surface of 11a and the vertical groove 311
a is formed on a part of the side surface of the inner surface. At this time, the vertical groove 31
The metal electrode 316 is formed on the metal electrode 310 formed on the first electrode 1a.
Is formed, and the metal electrode 316 formed on the side surface of the vertical groove 311a is electrically connected to the metal electrode 308 via the metal electrode 310. Therefore, the metal electrode 308 formed on the partition 306 on one side of the lateral groove 303a in which the vertical groove 311a is formed has the lateral groove 3 formed by the partition 306.
In the other lateral groove 303a sandwiching 03b, the lateral groove 30
It is electrically connected to a metal electrode 308 formed on another partition wall 306 forming 3b. In addition, the metal electrode 31
6 is electrically connected to the pattern 324.

Then, as shown in FIGS. 3 and 4, the metal electrode 317 is formed on the surface 3 of the piezoelectric ceramic plate 302.
02c, a region from the center side of the piezoelectric ceramic plate 302 to the end face 302b side of the bottom surface of the vertical groove 311b,
It is formed on the entire inner side surface of the vertical groove 311b and on the end surface 302b side of the vertical groove 311b. At this time, the metal electrode 3 is also formed on the metal electrode 308 of the lateral groove 303b communicating with the vertical groove 311b.
17 is formed and is electrically connected to the metal electrode 317 formed on the side surface of the vertical groove 311b. Therefore, the vertical groove 3
All metal electrodes 30 of the lateral groove 303b in which 11b is formed
8 are electrically connected by the metal electrode 317. In addition, the metal electrode 317 is electrically connected to the pattern 325.

Next, the piezoelectric ceramic plate 30
At least the second metal electrodes 308, 309, and 317 are covered with an epoxy resin protective film 77 (FIG. 6) by spin coating. Further, the protective film 77 also has a function as an insulating film.

In addition to the epoxy resin film formed by spin coating, a protective film 77 formed of another organic material such as acrylic resin or an inorganic material such as SiO ₂ may be formed by a dipping method, a CVD method, or the like.

Incidentally, the metal electrode 310 and the air chamber 3 described later.
Since the metal electrode 308 formed in the lateral groove 303a forming 27 is not in contact with the ink, it is not always necessary to cover it with the protective film 77.

Next, the cover plate 320 is made of a ceramic material or the like, and the surface of the piezoelectric ceramic plate 302 on the side where the lateral groove 303 is processed is bonded to the cover plate 320 with an epoxy adhesive 120 (FIG. 6). . Therefore, in the inkjet head 300, the upper surface of the lateral groove 303 is covered, and the ink chamber 304 (see FIG. 6) communicating with the vertical groove 311b and the air chamber 327 as a non-ejection region communicating with the vertical groove 311a (see FIG. 6). ) Is configured. The ink chamber 304 corresponds to the lateral groove 303b, and the air chamber 327 corresponds to the lateral groove 303a. The ink chamber 304 and the air chamber 327 have an elongated shape with a rectangular cross section, all the ink chambers 304 are filled with ink, and the air chambers 327 are regions filled with air.

Next, an opening 341 is provided at a position corresponding to the position of each ink chamber 304 on the end surface 302a of the piezoelectric ceramic plate 302 and the end surface of the cover plate 320, and a lead zirconate titanate (PZT) system is used. A seal plate 340 made of a ceramic material or the like is adhered with an epoxy adhesive or the like.

Then, a metal thin film layer 342 of Au is formed on the surface of the seal plate 340 that is to be bonded to the nozzle plate 1 described later by vapor deposition. At this time, the metal thin film layer 342 to be formed is not electrically connected to each metal electrode 309. If the metal thin film layer 342 is formed on the sheet plate 340 in advance, the metal thin film layer 342 is formed.
Is more preferable because it is not electrically connected to each metal electrode 309.

The film to be formed is not only Au but also Ag, Al and C.
u or the like can be used. In addition to the vapor deposition method, a sputtering method may be used.

Next, the opening 3 of the seal plate 340
The nozzle plate 1 provided with the nozzles 2 is bonded to the position corresponding to 41 (the position corresponding to the position of the ink chamber 304). As shown in FIG. 1, a nozzle 2 having an orifice portion 4 and a tapered portion 3 is formed on the nozzle plate 1.

As a method of manufacturing the nozzle plate 1, first, a molded product in which the tapered portion 3 is formed by injection molding is formed of polysulfone which is a resin material. And
The nozzle plate 1 is obtained by processing the orifice portion 4 with an excimer laser beam.

As the material of the nozzle plate 1, resin materials such as liquid crystal polymer, polyacetal, polyphenylsulfone, polyphthalamide, polyphenylene oxide, polyetherimide, polyethersulfone, polycarbonate and the like can be used in addition to polysulfone. it can.

Then, as shown in FIG. 4, the manifold member 301 has an end surface 302b of the piezoelectric ceramic plate 302 and a surface 30 of the piezoelectric ceramic plate 302.
2c is bonded to the vertical groove 311b side. A manifold 322 is formed on the manifold member 301, and the manifold 322 surrounds the vertical groove 311b.

The surface 30 of the piezoelectric ceramic plate 302
The patterns 324 and 325 formed on 2c are connected to a wiring pattern of a flexible printed board (not shown). The wiring pattern of the flexible printed circuit board is
It is connected to a rigid board (not shown) connected to a control unit described later.

Next, the configuration of the control unit will be described with reference to FIG. 5, which shows a block diagram of the control unit. The pattern 324 formed on the surface 302c of the piezoelectric ceramic plate 302
325 is individually connected to the LSI chip 151 via the flexible printed board and the rigid board, and the clock line 152, the data line 153, the voltage line 154, and the ground line 155 are also connected to the LSI chip 1.
It is connected to 51. The LSI chip 151 determines which nozzle 2 should eject an ink drop from the data appearing on the data line 153 based on the continuous clock pulse supplied from the clock line 152, and ejects the ink chamber 304. The voltage V of the voltage line 154 is applied to the patterns 324 that are electrically connected to the metal electrodes 308 of the air chambers 327 on both sides of. In addition, another pattern 32
4 and the pattern 325 electrically connected to the metal electrode 308 of the ink chamber 304 is connected to the earth line 155.

Next, the ink jet head 3 of the present embodiment.
00 will be described. The ink chamber 304b in FIG. 6B
To eject ink drops from the ink chamber 304b.
Ink chambers 304b of air chambers 327b and 327c on both sides of
A voltage pulse is applied to the metal electrodes 308c and 308f on the side through the pattern 324, and to the other metal electrodes 308,
It is grounded through the other patterns 324 and 325. Then, an electric field in the direction of arrow 113b is generated in the partition wall 306b, an electric field in the direction of arrow 113c is generated in the partition wall 306c, and the partition walls 306b and 306c move away from each other. The volume of the ink chamber 304b increases and the nozzle 2
The pressure in the ink chamber 304b including the vicinity decreases. This state is maintained for the time indicated by L / a. Then, during that time, ink is supplied from the manifold 322 to the ink chamber 304b through the vertical groove 311b. The above L / a
Is the time required for the pressure wave in the ink chamber 304 to propagate one way in the longitudinal direction of the ink chamber 304 (from the vertical groove 311b to the nozzle plate 14 or vice versa). S and the sound velocity a in the ink.

According to the propagation theory of the pressure wave, the pressure in the ink chamber 304b reverses and changes to a positive pressure just after the time of L / a from the start-up, but the electrodes 308c and 308f are synchronized with this timing. The voltage applied to is returned to 0V. Then, the partition walls 306b and 306c return to the state before deformation (FIG. 6A), and pressure is applied to the ink. At that time, the positive pressure and the partition wall 306b,
306c returns to the state before the deformation, and the generated pressure is added, and a relatively high pressure is applied to the ink in the ink chamber 304b, and an ink droplet is ejected from the nozzle 2.

In the ink jet head 300 of this embodiment as described above, the piezoelectric ceramic plate 3 is used.
02, cover plate 320 and seal plate 340
Has a coefficient of thermal expansion of about 2 × 10 ⁻⁶ / ° C., and the nozzle plate 1 has a coefficient of thermal expansion of about 56 × 10 ⁻⁶ / ° C., which are considerably different. Then, the nozzle plate 1 and the seal plate 3 are connected via Au having a coefficient of thermal expansion of approximately 14 × 10 ⁻⁶ / ° C.
No. 40 is bonded to the seal plate 340, the nozzle plate 1 did not separate from the seal plate 340 even after the thermal cycle test at −40 ° C. to 70 ° C., and good ink ejection was performed.

On the other hand, when the above-mentioned thermal cycle test was performed on the ink jet head in which the metal thin film layer 342 was not formed, the ink was ejected by peeling from the interface between the nozzle plate and the adhesive or the surface layer of the sheet plate. Bending and print quality deteriorated. Further, if the curing temperature is increased and the bonding is performed, the bonding strength is improved, but the thermal strain is large when exposed to -40 ° C, the piezoelectric ceramic plate is broken from the surface layer, and the printing quality is deteriorated.

On the other hand, in the ink jet head 300 of this embodiment, even if the bonding temperature is raised and the nozzle plate 1 and the seal plate 340 are bonded, -40
When exposed to ° C, the nozzle plate 1 did not peel off and the print quality did not deteriorate.

In this embodiment, the seal plate 340 is used.
Is provided and the metal thin film layer 342 is formed on the end face thereof to prevent electrical connection of the electrodes 308, 309, 310. However, the metal thin film layer 34 is directly provided on the end face 302a.
It is also possible to prevent the electrodes 308, 309, 310 from being electrically connected by the metal thin film layer 342 by, for example, grooving the end face 302a with a dicing blade after forming 2. At this time, the metal thin film layer 34 is provided between the nozzle plate 1 and the piezoelectric ceramic plate 302 and the cover plate 320 only in the grooved portion.
2 does not exist, but there is no functional problem.

Further, in the above embodiment, first, the drive voltage is applied in the direction in which the volume of the ink chamber 304b increases,
Next, the application of the drive voltage was stopped, the volume of the ink chamber 304b was reduced to a natural state, and the ink droplets were ejected from the ink chamber 304b. First, the drive voltage was applied so that the volume of the ink chamber 304b decreased. To eject ink droplets from the ink chamber 304b, and then stop applying the drive voltage to the ink chamber 3b.
Ink may be supplied into the ink chamber 304b by increasing the volume of 04b from the reduced state to the natural state.

In this embodiment, the partition wall 306 is made of piezoelectric ceramics. However, the upper half region of the partition wall is made of piezoelectric ceramics, and the lower half is made of a material other than piezoelectric ceramics such as alumina. Good.

Further, in this embodiment, the ink is ejected from the ink chamber 304 by the piezoelectric deformation of the upper half region of the partition wall 306, but in the direction opposite to the polarization direction of the piezoelectric ceramics in the upper half region of the partition wall. It is also possible to form a lower half region of the partition wall by using piezoelectric ceramics that is the polarization direction, form a metal electrode on the entire side surface of the partition wall, and eject the ink from the ink chamber by piezoelectric deformation of the entire partition wall.

Further, in the present embodiment, the ink jet head using piezoelectric ceramics is applicable, but it is applicable to various well known ink jet heads such as a bubble jet type and a continuous jet type.

[0043]

As is apparent from the above description, according to the ink jet head of the present invention, since the metal layer is provided on the joint portion of either one or both of the nozzle plate and the head body, the nozzle plate Even if there is a large difference in thermal expansion between the head body and the head body, the nozzle plate does not separate from the head body, ink can be ejected well, and printing quality is excellent.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a nozzle portion of an embodiment of the present invention.

FIG. 2 is a perspective view showing an inkjet head of the embodiment.

FIG. 3 is a perspective view showing the piezoelectric ceramic plate of the embodiment.

FIG. 4 is a perspective view showing the inkjet head of the embodiment.

FIG. 5 is a block diagram showing a control unit of the inkjet head of the embodiment.

FIG. 6 is an explanatory diagram showing an operating state of the inkjet head of the embodiment.

[Explanation of symbols]

 1 Nozzle Plate 2 Nozzle 3 Tapered Part 4 Orifice Part 300 Inkjet Head 302 Piezoelectric Ceramics Plate 320 Cover Plate 340 Seal Plate 342 Metal Thin Film Layer

Claims (3)

[Claims] 1. An ink jet head comprising: a nozzle plate having a plurality of nozzles for ejecting ink; and a head main body having an ink chamber communicating with the nozzles and for giving energy to the ink in the ink chamber. An inkjet head, wherein a metal layer is provided on a joint portion of one or both of the nozzle plate and the head main body. 2. The ink jet head according to claim 1, wherein the nozzle plate is formed by an injection molding method, and the head main body is formed of piezoelectric ceramics. 3. The ink jet head according to claim 1, which is used in an environment of −40 ° C. to 80 ° C.