JP3439659B2 - Piezoelectric vibrator unit for ink jet print head, method of manufacturing the same, and ink jet print head - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, when a print signal is input, causes ink in a pressure chamber to fly as droplets from a nozzle opening onto a recording medium, and the ink droplets form dots on the recording medium for printing. The present invention relates to a piezoelectric vibrator unit suitable for an inkjet print head.

[0002]

2. Description of the Related Art So-called ink jet type print heads that form droplets by inputting a print signal are roughly classified into three types, the first type of which vaporizes ink instantaneously. A so-called bubble jet type in which a heater is provided at the tip of the nozzle to generate and fly ink droplets by the expansion pressure when the ink vaporizes, and the second
In this type, a part of the container forming the ink reservoir is composed of a piezoelectric element that is deformed by a print signal, and the pressure in the container caused by the deformation of the piezoelectric element causes the ink to fly as droplets. The third type is one in which a piezoelectric element is provided in a pressure chamber having a nozzle opening, and the ink pressure in the pressure chamber is changed by expansion and contraction of the piezoelectric element to cause ink to fly from the nozzle as droplets.

The ink jet type print head of the third type is disclosed in Japanese Patent Publication No. 2-45985 and Japanese Patent Publication No. 45985.
As disclosed in JP-A-52-62525, a vibrating film that forms a pressure chamber by fixing a plurality of piezoelectric vibrators having electrodes formed on both sides of a long piezoelectric material plate and fixing one end of the piezoelectric vibrator to a base. The vibrating film is deformed by the expansion and contraction of the piezoelectric element, and the ink in the pressure chamber is ejected as droplets from the nozzle opening.

[0004]

However, in order to obtain a displacement amount sufficient to eject ink droplets, it is necessary to apply a high electric field to the piezoelectric material plate, and high electrical insulation that can withstand the high voltage applied. Therefore, there is a problem in that the insulation structure becomes complicated due to the necessity of the property. In addition, since the entire piezoelectric vibrator is configured as a displacement area, that is, an active area, the area fixed to the base is also displaced, and the adhesive is easily fatigued, resulting in a lack of reliability. In addition, it is necessary to align and position the base having a relatively large size and the vibrating membrane, and there is a problem that the alignment work is extremely difficult when a large number of nozzles are arranged at high density. Further, there is a problem that it is difficult to route the lead wire because it is necessary to connect the two electrodes formed on both surfaces of the piezoelectric material plate to the drive signal supply source.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a piezoelectric vibrator unit for an ink jet type print head which can solve these problems at once. Is. Another object of the present invention is to propose a method for manufacturing the above piezoelectric vibrator unit. Still another object of the present invention is the same as above.
If the piezoelectric vibrator unit is used as an actuator
It is to provide an ink jet type print head.

[0006]

In order to solve such a problem, a piezoelectric vibration for an ink jet print head according to the present invention is used.
Doko unit weight and a piezoelectric material, a first conductive <br/> electrode layer constituting one of the poles, is in the active region and the second electrode layer constituting the other pole
So that the second electrode layer extends to the free end.
Exists in the range of the active region, and
Electrode layer from near the free end to the end of the inactive region
And further the presence of the second electrode layer in the inactive region
The area not to be formed is flush with the second electrode layer,
Is electrically conductively separated from the second electrode layer by a piezoelectric material.
Formed with a layer of the same material as the second electrode layer
Multiple oscillators so that the active area is a free area
The inactive region is fixed to the substrate.

[0007]

The function of the second electrode forming the electrode of the active region is also in the inactive region.
The second electrode layer is on the same plane as the electrode layer, and the second electrode layer is a piezoelectric material.
Made of the same material as the second electrode layer that is conductively divided by the material
Since the layers are formed, the entire vibrator is electrically connected to the piezoelectric material layer.
It has a homogenous structure with the pole material layer, and changes due to temperature and aging.
It is possible to prevent warping and bending. Also, the piezoelectric vibrator
A plurality of inactive areas so that the active area is a free area.
Since it is fixed to the board, there is no displacement in the fixed area with the board.
It can prevent adhesive fatigue and ensure reliability.
It

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will now be described based on the illustrated embodiments. FIG. 1 shows an appearance of a print head using the piezoelectric vibrator unit of the present invention. In the figure, reference numeral 1 is a base that also serves as a carriage mounting member, and a head 2 when mounted on a carriage.
As shown in FIG. 2, independent main tanks 3 and sub-tanks 4 are provided at positions lower than that, and partition plates 3a, 3a, 3a ... 4a, 4a, 4 are provided inside the tanks.
is provided.

The base 1 has a portion 7 forming a tank body.
And a lid member 8 that seals the front surface of the sub tank 4. The tank main body 7 is provided with an ink supply port 10 above the main tank 3 and the sub tank 4 is open to the atmosphere. A port 11 is provided, and a heater mounting hole 12 is provided between these tanks 3 and 4 in case of using hot melt ink.

On the other hand, the lid member 8 is composed of a front plate 14 and a back plate 15. Arms 13, 13 for supporting the print head 2 are provided on the front surface of the front plate 14 and a back plate 15 is provided on the back surface. Grooves 14a and 14b forming a flow path for communicating the tanks 3 and 4 and the nozzle assembly 2 in cooperation with each other are formed,
Through holes 14c and 14d communicating with the ink supply port of the nozzle assembly 2 are formed at the upper ends of the grooves 14a and 14b. Further, the back plate 15 is formed by the grooves 1 formed in the front plate 14.
Through holes 15a and 15b which communicate with the lower ends of the 4a and 14b are formed so that the respective grooves 14a and 14b are communicated with the lower surfaces of the main tank 3 and the sub tank 4. Note that reference numeral 16 in the figure denotes an ink receiving member at the time of ink supply.

FIGS. 3A, 3B, and 4 show an embodiment of the nozzle assembly, which is designated by reference numeral 30 in the drawings.
Is the nozzle plate and the paper feed direction (up and down direction in the figure)
In addition, a plurality of nozzle openings 31, 31, 31 are formed in one row, and a plurality of such nozzle opening rows are arranged in the sub-scanning direction (horizontal direction in the drawing). These nozzle openings 31, 31, 31 ...
Are separated by 2, 32, 32, ..., And ink is supplied from the ink flow paths 33, 33, 33 ,.

Reference numeral 34 in the drawing denotes a diaphragm which is arranged at a constant distance from the nozzle plate 30 so as to form pressure chambers 35, 35, 35 with the nozzle plate 30, and one end of which is a base plate. It is fixed to the tip of a support member 37 fixed to the table 36. Grooves 3 for supplying ink to the pressure chambers 35, 35 are provided on the side of the support member 37 facing the nozzle plate.
3, the diaphragm 34 is supported at the tip of the wall surface 38 thereof.

As a result of adopting such a structure, the ink flows into the pressure chamber 35 from the groove 33 having a relatively small fluid resistance by the flow indicated by the arrow B in the figure, and the vibrator 40 described later can be isolated from the ink. Even when the conductive ink is used, it is possible to prevent a short circuit between the electrodes of the vibrator.

Reference numeral 40 denotes the above-mentioned vibrator, which extends in the longitudinal direction.
As will be described later, the axial direction is divided into two upper and lower regions, and the inactive region side (the lower side in the figure) has a material having a larger acoustic impedance than the oscillator 40 on both sides thereof, such as alumina or metallic silicon. Substrates 41 and 42 composed of are bonded and fixed to the base 36 via the substrate 41. On the other hand, the active area of the oscillator 40 is a free area,
A pressure transmission member 43 is fixed to the tip of the pressure transmission member 43, and is connected to the diaphragm 34 via the pressure transmission member 43.

By adopting such a structure, even if the vibrator 40 repeatedly expands and contracts, the substrates 41, 4
2 does not generate strain on the bonding surface between the oscillator 40 and the oscillator 40, and fatigue is extremely reduced to reduce the oscillator 40 and the substrates 41, 4 and 4.
2. The life of the adhesive layer can be extended. Also,
Since the acoustic impedance of the substrates 41 and 42 is larger than that of the oscillator 40, the acoustic waves generated in the oscillator 40 are transmitted to the substrate 4
By virtue of the positive reflection on the surfaces of Nos. 1 and 42, it is possible to prevent the improper vibration and transmit the vibration component effective for ink ejection to the vibration plate 34.

Further, since the vibrator 40 and the vibration plate 34 are connected via the pressure transmitting member 43, when the small vibrator is used, the pressure transmitting member 43 is larger than the end surface area of the vibrator 40. Further, by making the area smaller than the area of the vibration plate 34, expansion and contraction of the vibrator 34 can be efficiently transmitted to the vibration plate 34.

FIG. 5 shows an embodiment of the above-described vibrator 40, which is a silver paste prepared on a surface plate in a paste form.
A layer of the first electrode 50 made of a conductive coating of palladium (Ag-Pd) or platinum (Pt), and a piezoelectric element material prepared in a paste form, for example, a titanate / lead zirconate-based composite perovskite ceramic material. The second layer to be the piezoelectric layer 52 is further formed by silver-palladium (Ag
-Pd) -based or platinum (Pt) -based conductive paint is used to alternately thinly coat the third layers to form the second electrodes 51, 51, 51.

At this time, when one of the electrodes, that is, the electrode 51 in this embodiment, is formed, it is cut off at substantially the central portions 54, 54 and dispersed at two axial positions on the same plane, and the first electrode is also formed. The electrode constituent material is applied so that 50 is exposed from one end surface (the right end surface in the drawing) and the second electrode 51 is exposed from the other end surface (the left end surface in the drawing). The plate-shaped product having a predetermined number of layers is dried and then baked at a temperature of 1000 to 1200 ° C. for about 1 hour while applying pressure.

In this way, in the one-sheet vibrator plate, one end of the first electrode 50, 50, 50, which is one pole, is exposed at one end face and the other end is covered with the piezoelectric material layer. Further, one end of each of the second electrodes 51, 51, 51, ... Is exposed on the other end face of the vibrator plate, and the other end is covered with the piezoelectric material layer.

The vibrator plate is made by cutting the vibrator plate into a strip shape having a predetermined size with a dicer or a diamond cutter, or by making a comb tooth-shaped cut so as to leave one end.

Then, conductive layers 55 and 56 are formed on each end face of the vibrator.
The electrodes 50, 50, 50 of the same polarity can be connected in parallel by the conductive layer 55, and the electrodes 51, 51, 51 can be connected in parallel by the conductive layer 56.
5, 56 are conductive layers 5 formed on the substrates 41 and 42.
External connection can be made by fixing to 7, 58 with a conductive adhesive. In the vibrator configured by such a method, the piezoelectric layers 52, 52, 52, ... Constituting the vibrator are extremely thin, and the electrodes 50, 51 that provide a driving electric field are connected in parallel. Will operate at a relatively low voltage.

Further, since the one electrode 51, 51, 51 is electrically divided by the piezoelectric material in the central region 54, 54, 54, ..., Excitation voltage is applied only to the free end side (left side in the figure). Since the voltage is not applied to the regions that are expanded and contracted and fixed to the substrates 41 and 42, an unreasonable force does not act when the excitation signal is applied, and not only the life can be extended, but also the vibration is generated. Since the entire child has a homogeneous structure of the piezoelectric material layer and the electrode material layer, it is possible to prevent warpage and bending due to temperature and aging.

The vibrator 40 having such a structure is shown in FIG.
As shown in FIG. 5, the cup-shaped pressure transmission member 60 having a concave portion slightly larger than the size of the vibrator tip on the back end at the free end side is arranged so that the concave side faces the vibrator 40. The heat-resistant adhesive 61 is applied to cover the remaining space.
Is fixed by pouring, and is surely brought into contact with the vibration plate 62.

[0024]

As described above, in the present invention,
In the inactive region, the second electrode layer forming the electrode of the active region
It is on the same plane, and the second electrode layer is made of a piezoelectric material.
A layer of the same material as the second electrode layer that is electrically conductively separated is formed
Because it is, the whole vibrator is a homogeneous structure of the piezoelectric material layer and the electrode material layer, it is possible to prevent warping or bending due to temperature or aging, also the piezoelectric vibrator, a plurality,
Since the active region becomes the free region and the inactive region is fixed to the substrate, there is no displacement in the region fixed to the substrate, fatigue of the adhesive can be prevented, and reliability can be ensured. It can be easily positioned with respect to the pressure generating chamber.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a print head using a piezoelectric vibrator unit of the present invention.

FIG. 2 is an exploded perspective view showing an example of a base that constitutes a print head.

3A and 3B show an embodiment of the nozzle assembly of the recording head, wherein FIG. 3A is a front view of the nozzle assembly, and FIG. 3B is A in FIG. It is a figure which shows the cross section in the -A line.

FIG. 4 is a perspective view showing an embodiment of the nozzle assembly of the present invention.

FIG. 5 is a sectional view showing an embodiment of a vibrator unit of the present invention.

FIG. 6 is a cross-sectional view showing a connection structure between a vibrator and a vibration plate of the same piezoelectric vibrator unit.

[Explanation of symbols]

34 diaphragm 35 Pressure chamber 37 Support member 40 oscillators 41, 42 substrate 43 Pressure transmission member 50, 51 electrodes 52 Piezoelectric material 55, 56 Conductive layer

─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shinji Yasukawa 3-3-5 Yamato, Suwa City, Nagano Seiko Epson Corporation (72) Inventor Norihiko Kurashima 3-3-5 Yamato, Suwa City, Nagano Prefecture Sei Co-Epson Co., Ltd. (72) Inventor Fujio Akabane 3-3-5 Yamato, Suwa-shi, Nagano Sei Co-Epson Co., Ltd. (72) Inventor Toshiaki Oshima 3-3.5 Yamato, Suwa-shi, Nagano Seiko Epson Incorporated (72) Inventor Toshio Kumagai 3-5 Yamato, Suwa, Nagano Seiko Epson Corporation (72) Inventor Katsuhiko Iida 3-5 Yamato, Suwa, Nagano Seiko Epson Corporation (72) Inventor Takahiro Katakura 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (56) Visit References JP-A-3-197049 (JP, A) JP-A-2-194960 (JP, A) JP-A-60-90770 (JP, A) Patent 2998764 (JP, B2) Patent 3070625 (JP, B2) Patent 3067195 (JP, B2) Patent 3060595 (JP, B2) Patent 3036548 (JP, B2) Patent 3228338 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2 / 16

Claims (16)

(57) [Claims] 1. The second electrode layer is a free end so that the piezoelectric material, the first electrode layer forming one pole, and the second electrode layer forming the other pole overlap in the active region. The first electrode layer is present in the range of the active region so as to extend to the tip, the first electrode layer extends from the vicinity of the free end to the end of the inactive region, and the second electrode layer of the inactive region is further provided. A piezoelectric element in which a layer of the same material as that of the second electrode layer is formed in the non-existing region and which is flush with the second electrode layer and is electrically conductively separated from the second electrode layer by a piezoelectric material. A piezoelectric vibrator unit for an inkjet print head, comprising a plurality of vibrators, and the inactive region is fixed to a substrate so that the active region is a free region. 2. The piezoelectric vibrator unit for an inkjet print head according to claim 1, wherein the piezoelectric material and the electrode layer are laminated in a direction perpendicular to the surface of the substrate. 3. The piezoelectric vibrator unit for an inkjet print head according to claim 1, wherein the piezoelectric vibrator extends in a direction orthogonal to a stacking direction of the piezoelectric material and the electrode layer. 4. One end of an electrode layer serving as one pole is exposed at one end face, the other end is covered with a piezoelectric material layer, and one end of an electrode layer serving as the other pole is exposed at the other end face.
The piezoelectric vibrator unit for an inkjet print head according to claim 1, wherein the other end is covered with a piezoelectric material layer. 5. The piezoelectric vibrator unit for an ink jet print head according to claim 4, wherein the electrode layers exposed on the respective end faces are connected in parallel by a conductive layer formed outside. 6. The ink jet type according to claim 1, wherein a tip of a free region of the piezoelectric vibrator is in contact with a driven member via a pressure transmission member having an area larger than a sectional area of the piezoelectric vibrator. Piezoelectric vibrator unit for print head. 7. The piezoelectric vibrator unit for an inkjet print head according to claim 1, wherein a conductive layer is formed on at least a surface of the substrate facing the piezoelectric vibrator. 8. A piezoelectric material is interposed between the conductive materials forming the electrode layers having different poles, and the conductive material forming the electrode layer serving as one pole is interrupted at the boundary between the inactive region and the active region. And laminating, drying at a stage when a predetermined number of layers have been laminated, firing while applying pressure to form a piezoelectric material plate, and inactivating the piezoelectric material plate with the active region. A method for manufacturing a piezoelectric vibrator unit for an ink jet type print head, which comprises a step of dividing the piezoelectric vibrator unit in the stacking direction so as to include a region. 9. The method for manufacturing a piezoelectric vibrator unit for an ink jet type print head according to claim 8, including a step of forming external electrodes on both surfaces in the stacking direction after firing. 10. An ink jet print head for ejecting ink droplets by pressurizing a pressure chamber communicating with a nozzle opening with an actuator, wherein the actuator comprises a piezoelectric material, a first electrode layer forming one pole, and the other. Exists in the range of the active region such that the second electrode layer extends to the free end so that the second electrode layer forming the pole of the second electrode layer overlaps in the active region, and the first electrode layer is The region extending from the vicinity of the free end to the end of the inactive region is flush with the second electrode layer in the region of the inactive region where the second electrode layer does not exist, and the second electrode A layer is a plurality of piezoelectric vibrators in which a layer made of the same material as the second electrode layer, which is conductively separated by a piezoelectric material, is formed, and the inactive region is formed on the substrate so that the active region is a free region. Fixed to Ink jet print head being. 11. The ink jet print head according to claim 10, wherein the piezoelectric material and the electrode layer are laminated in a direction perpendicular to the surface of the substrate. 12. The ink jet print head according to claim 10, wherein the piezoelectric vibrator extends in a direction orthogonal to a stacking direction of the piezoelectric material and the electrode layer. 13. One end of an electrode layer serving as one pole is exposed at one end face, the other end is covered with a piezoelectric material layer, and one end of an electrode layer serving as the other pole is exposed at the other end face, 11. The other end is covered with a piezoelectric material layer.
The ink jet type print head according to 1. 14. The ink jet print head according to claim 13, wherein the electrode layers exposed on the respective end faces are connected in parallel by a conductive layer formed outside. 15. The vibrating plate forming the pressure chamber is abutted by a tip of a free region of the vibrator via a pressure transmission member having an area larger than a cross-sectional area of the piezoelectric vibrator. Inkjet print head described. 16. The ink jet print head according to claim 10, wherein a conductive layer is formed on at least a surface of the substrate facing the piezoelectric vibrator.