JP3728932B2 - Inkjet recording head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording head used in an ink jet recording apparatus for forming characters and images by ejecting ink droplets, and an ink jet recording head in which a piezoelectric vibration body in a flexural vibration mode is attached to the surface of a vibration plate. About.
[0002]
[Prior art]
Conventionally, a multilayer ink jet recording head in which a nozzle plate, a pressure generating chamber, and a diaphragm are laminated and a piezoelectric vibrator in a flexural vibration mode is attached to the surface of the diaphragm is known (for example, a special table flat surface). No. 5-504740). Usually, most of the members constituting the multilayer ink jet recording head are made of ceramic. Therefore, each member can be fixed without using an adhesive by laminating and firing the respective members in a green sheet (clay-like sheet) state. As a result, there is an advantage that a process for bonding the respective layers to each other becomes unnecessary, and the manufacturing process can be simplified.
[0003]
[Problems to be solved by the invention]
However, as the density of recording heads and the increase in the number of nozzles progress at an accelerated pace, the impedance of electrodes that apply drive signals to the piezoelectric vibrator, particularly the common electrode formed across multiple piezoelectric vibrators, increases. However, the problem that the driving signal waveform becomes dull and the ink flight state is not stable has become remarkable. The resistance value of the electrode is generally inversely proportional to the thickness and width, and proportional to the length. However, if the electrode is partially formed on the ceramic substrate and the piezoelectric vibrator is formed on the ceramic substrate as in the past, The common electrode must be formed at a position apart from the plurality of pressure generating chambers, and increasing the width of the common electrode has the problem of directly increasing the length of the recording head. .
[0004]
In addition, the amount of deflection of the diaphragm is optimized by the balance between the rigidity of the piezoelectric vibrator and the rigidity of the diaphragm and the electrode. However, as the electrode thickness is increased, the rigidity of the piezoelectric vibrator is balanced. There was a problem that the required amount of deflection of the diaphragm could not be obtained. In order to increase the amount of deflection of the diaphragm at the same voltage, there is a means to reduce the thickness of the piezoelectric vibrator and reduce the thickness of the diaphragm in proportion to this, but the thickness of the diaphragm is reduced. The more the problem is, the more the above problem becomes.
[0005]
Furthermore, as another problem, as the thickness of the piezoelectric vibrating body is reduced, when the piezoelectric vibrating body is formed outside the pressure generating chamber, the stress applied to the piezoelectric vibrating body is concentrated at the boundary of the pressure generating chamber. As a result, there is a problem in that the piezoelectric vibrator is cracked.
[0006]
Accordingly, an object of the present invention is to provide an ink jet type recording head that can obtain a stable ink flight state even with a high density and multiple nozzles and has high reliability.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an ink jet recording head of the present invention comprises a pressure generating chamber communicating with a nozzle, and a piezoelectric vibrating body that applies flexural vibration to the pressure generating chamber. In an ink jet recording head that discharges ink in a generation chamber from the nozzle,
A pressure generating chamber forming member that forms the pressure generating chamber; a vibration plate made of a conductive member that forms one wall surface of the pressure generating chamber; and the pressure generating chamber at a position on the vibrating plate facing the pressure generating chamber. A piezoelectric vibrator formed in a region smaller than both of the long side direction and the short side direction, an electrical insulating layer formed so as to overlap with a part of the piezoelectric vibrator, and the piezoelectric vibrator from above And an electrode layer formed up to the electrical insulating layer.
[0008]
In addition, a part of the piezoelectric vibrator is formed on the electrical insulating layer so as to overlap.
[0009]
In addition, a part of the electrical insulating layer is formed to overlap the piezoelectric vibrator.
[0010]
The thickness of the electrical insulating layer is substantially the same as the thickness of the piezoelectric vibrating body.
[0011]
Further, an adhesion layer is formed on the electrical insulating layer.
[0012]
The adhesion layer is formed of Ti, Pt, Cr, or a material containing at least one component thereof.
[0013]
Further, the individual electrode and the terminal electrode are formed on the electrical insulating layer so as to overlap each other.
[0014]
Further, the surface of the pressure generating chamber forming member opposite to the surface on which the diaphragm is formed is provided with a nozzle plate in which nozzle openings are formed, a reservoir forming substrate in which a common ink chamber is formed, and a through hole serving as a flow path. It is characterized by laminating a flow path forming member made of a lid plate on which is formed.
[0015]
The diaphragm is a common electrode, and the common electrode is electrically connected to the terminal electrode on the electrical insulating layer.
[0016]
The terminal electrode connected to the individual electrode and the terminal electrode connected to the common electrode are arranged in a line.
[0017]
[Action]
By using a diaphragm whose entire surface is a conductive member, the impedance of the common electrode can be made as small as possible, and even in a high-density, multi-nozzle multi-layer ink jet recording head, the driving waveform is prevented from being dull. And the ink flight state can be stabilized. In addition, since the piezoelectric vibrating body is formed only in the inner region of the pressure generating chamber, an ink jet recording head having high reliability can be achieved without stress concentration in the boundary region.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Therefore, the details of the present invention will be described below based on the illustrated embodiment.
[0019]
FIG. 1 shows an embodiment of an ink jet recording head according to the present invention.
[0020]
Reference numeral 61 denotes an actuator part of the ink jet recording head, which is composed of at least the spacer 10, the diaphragm 13, and the piezoelectric vibrators 14 and 15.
[0021]
The spacer 10 which is a pressure generation chamber forming substrate has a thickness suitable for constituting the pressure generation chambers 11 and 12 having a depth of about 100 μm, for example, a single crystal silicon substrate, a non-rust steel substrate, zirconia (ZrO). ₂ ) Made of ceramic plate.
[0022]
The diaphragm 13 is configured to seal one surface of the spacer 10. The diaphragm 13 is conductive and is made of a material that is elastically deformed by bending displacement of piezoelectric vibrators 14 and 15 described later. In the present invention, the diaphragm 13 is a thin plate having a thickness of about 4 μm. Examples of the material of the diaphragm include metals such as titanium (Ti), platinum (Pt), and stainless steel, or FC Report Vol8 No. 7 (1990) et al., Zirconium boride, chromium carbide (Cr ₃ C ₂ ), titanium boride, titanium carbide (TiC), titanium nitride (TiN) or zirconium boride and boron nitride ( It is also possible to form a thin plate of a conductive ceramic material made of a composite material with BN) or silicon carbide (SiC).
[0023]
The piezoelectric vibrating bodies 14 and 15 are formed on the surface of the vibration plate 13 at a position facing the pressure generating chamber. In the present invention, the piezoelectric body is formed by printing and baking a piezoelectric green sheet on the vibration plate 13. As a method of forming the piezoelectric vibrator, the fired piezoelectric vibrator is bonded to the diaphragm with an adhesive, or formed using a hydrothermal method (hydrothermal synthesis method) using a titanium layer as a growth substrate, It can also be formed by a sputtering method or a sol-gel method.
[0024]
Next, reference numeral 60 denotes a flow path forming member constituting the ink jet recording head, which is formed by laminating the cover plate 16, the reservoir forming substrate 17, and the nozzle plate 3.
[0025]
The cover plate 16 is attached to the other surface of the spacer 10 of the actuator unit 51. In this embodiment, it is made of a stainless steel substrate having a thickness of 100 μm, and nozzle communication ports 4 and 5 for connecting the nozzle openings 1 and 2 and the pressure generating chambers 11 and 12, the reservoirs 6 and 7, and the pressure generating chambers 11 and 12. Ink supply ports 8 and 9 for connecting the two are formed.
[0026]
The reservoir forming substrate 17 is connected to an ink introduction port 18, 19 provided on the cover plate 16 on a plate material having corrosion resistance such as 200 μm stainless steel suitable for forming an ink flow path, and external ink. Reservoirs 6 and 7 that receive ink supply from the tank and supply ink to the pressure generating chambers 11 and 12 from the ink supply ports 8 and 9, and nozzle communication that connects the pressure generating chambers 11 and 12 and the nozzle openings 1 and 2. The mouths 20 and 21 are formed.
[0027]
The nozzle plate 3 is formed with nozzle openings 1 and 2 at a predetermined pitch, and communicates with the pressure generating chambers 11 and 12 through nozzle communication ports 4, 5, 20, and 21.
[0028]
The nozzle plate 3, the reservoir forming substrate 17, and the cover plate 16 are joined by a joining method suitable for each member such as adhesion and thermocompression bonding to form a flow path forming member 50. The flow path forming member 50 is an actuator unit. When the ink-jet recording head is bonded, the ink-jet recording head is combined.
[0029]
2 and 3 are a top view and a cross-sectional view showing details of the pressure generating part, respectively, and the piezoelectric vibrating bodies 14 and 15 are formed corresponding to the pressure generating chambers 11 and 12, respectively. The width in the arrangement direction is narrower than the width of the pressure generation chambers 11 and 12, and is formed to be, for example, about 0.7 times the width of the pressure generation chambers 11 and 12. The piezoelectric vibrating bodies 14 and 15 are also formed shorter in the longitudinal direction of the pressure generating chambers 11 and 12 than the pressure generating chambers 11 and 12. Therefore, since the piezoelectric vibrating body does not receive stress concentration at the boundary portion of the pressure generating chamber, a highly reliable ink jet recording head that does not generate cracks or the like of the piezoelectric vibrating body is possible.
[0030]
On the upper surfaces of the piezoelectric vibrators 14 and 15, individual electrodes 23 narrower than the piezoelectric vibrators 14 and 15 are formed.
[0031]
In the region other than the region where the pressure generating chambers 11 and 12 of the diaphragm 13 are formed, an electric material made of a ceramic material such as zirconia (ZrO ₂ ) or alumina (Al ₂ O ₃ ), or a resin material such as polyimide or epoxy. Insulating layers 24 and 25 are formed, and are formed so as to extend in part of the region of the pressure generating chambers 11 and 12 (reference numerals 26 and 27 in FIG. 2). The electrical insulating layers 26 and 27 formed in the region of the pressure generating chambers 11 and 12 are formed to have substantially the same width as that of the piezoelectric vibrating bodies 14 and 15. In addition, the electrical insulating layers 24, 25, 26 and 27 are formed to be substantially the same as the thickness of the piezoelectric vibrating bodies 14 and 15.
[0032]
On the electrical insulating layers 24 and 25, adhesion layers 28 and 29 made of titanium (Ti) formed in a stripe shape are formed. The adhesion layer may be a material having excellent adhesion to other piezoelectric vibrators, for example, a material such as platinum (Pt), chromium (Cr), or an alloy, oxide, or nitride containing at least those. The piezoelectric vibrating bodies 14 and 15 extend so as to overlap the electrical insulating layers 28 and 29 and are formed to correspond to the piezoelectric vibrating bodies 14 and 15. The widths of the adhesion layers 28 and 29 are formed to be equal to the width of the piezoelectric vibrators 14 and 15.
[0033]
Since the adhesion layers 28 and 29 are formed, the piezoelectric vibrators 14 and 15 and the electrical insulating layers 24 and 25 are firmly fixed and fixed via the adhesion layers 28 and 29. The individual electrode 23 extends from a region overlapping with the electrical insulating layers 24 and 25 of the piezoelectric vibrators 14 and 15 to reach the adhesion layers 28 and 29, and a part thereof is the adhesion layers 28 and 29. Formed on top. Since the piezoelectric vibrators 14 and 15 are formed in close contact with the electrical insulating layers 24 and 25 via the adhesion layers 28 and 29, the individual electrodes 23 can be surely attached to the adhesion layers even by the vibration of the piezoelectric vibrators 14 and 15. 28 and 29 can be ensured electrically reliably and with high reliability.
[0034]
Terminal electrodes 30 and 31 are formed so as to overlap a part of the adhesion layers 28 and 29. The terminal electrodes 30 and 31 are made of silver having a thickness of about 10 μm, for example. The terminal electrodes 28 and 29 are connected to the drive signal control circuit by a flexible cable (not shown) by a method such as soldering.
[0035]
Since the electrical insulating layers 26 and 27 extending to a part of the pressure generating chambers 11 and 12 are formed with substantially the same width and the same thickness as the piezoelectric vibrating bodies 14 and 15, 12, the vibration shapes of the diaphragm 13 and the piezoelectric vibrators 14 and 15 become smooth, and the occurrence of cracks and the like of the piezoelectric vibrator can be further suppressed.
[0036]
In the region outside the arrangement direction of the piezoelectric vibrators 14 and 15, the common terminal electrodes 33 and 34 are formed on the electrical insulating layer so as to contact the diaphragm 13. Similar to the terminal electrodes 30 and 31, the common terminal electrodes 33 and 34 are made of, for example, silver having a thickness of about 10 μm. And it is connected to the drive signal control circuit by the flexible cable mentioned above. By applying drive signals to the common terminal electrodes 33, 34 and the terminal electrodes 30, 31, a voltage is applied between the diaphragm 13 formed of a conductive member and the individual electrodes 23, and the piezoelectric vibrators 14, 15. And the vibration plate 13 vibrate, the pressure in the pressure generating chamber 10 increases, and ink is ejected from the nozzle openings 1 and 2 as ink droplets.
[0037]
The diaphragm 13 made of a conductive member is formed in almost the entire region of the spacer 11 and is formed to be as thick as possible. Therefore, the impedance can be made extremely small, and the pressure generating chamber can be formed at a high density, for example, 140 μm pitch. Even in an ink jet recording head having a number of nozzles of 1000 nozzles or more, such as a line head having a large number of nozzles, for example, a width equivalent to the width of the recording paper, the drive waveform is stable and stable. Ink ejection can be obtained.
[0038]
In the above-described embodiment, the piezoelectric vibrating body is formed so as to partially cover the electric insulating layer. However, as shown in FIG. 4, the electric insulating layer 51 is formed so as to cover a part of the piezoelectric vibrating body 50. May be. In the case of this embodiment, the individual electrode 52 is formed so as to be continuous with the electrical insulating layer 51 from above the piezoelectric vibrator. A terminal electrode 53 is formed so as to cover a part thereof, and is connected to a drive signal control circuit (not shown) by a joining means such as soldering via a flexible cable (not shown).
[0039]
In the above-described embodiment, when the nozzle openings are arranged in a plane on the nozzle plate and ink is ejected in the deflection direction of the piezoelectric vibrator, a so-called face eject type has been described as an example. When the ink is ejected in the direction perpendicular to the direction, the same effect is obtained in the so-called edge eject type.
[0040]
【The invention's effect】
As described above, according to the ink jet recording head of the present invention, the impedance of the electrode can be made extremely small by having a diaphragm made of a conductive member and applying a drive signal using the diaphragm as a common electrode. Therefore, even in a high-density, multi-nozzle ink jet recording head, the drive signal can be accurately transmitted to the piezoelectric vibrating body without being dull, and a stable ink flight state can be achieved.
[0041]
In addition, by extending an electric insulating layer in a part of the pressure generating chamber and forming the piezoelectric vibrating body smaller than the pressure generating chamber, a highly reliable ink jet recording head that does not generate cracks in the piezoelectric vibrating body can be obtained. Can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the structure of an ink jet recording head according to an embodiment of the present invention.
FIG. 2 is a top view showing details in the vicinity of a pressure generation chamber of the recording head of FIG.
3 is a cross-sectional view showing details in the vicinity of an electrical insulating layer portion of the recording head of FIG. 1. FIG.
FIG. 4 is a cross-sectional view showing details in the vicinity of an electrical insulating layer according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2 Nozzle opening 10 Pressure generation chamber 13 Diaphragm 14, 15 Piezoelectric vibration body 23 Individual electrodes 24, 25 Electrical insulation layers 26, 27 Electrical insulation layers 28, 29 formed extending in the pressure generation chamber Adhesion layer

Claims (10)

In an ink jet recording head comprising a pressure generating chamber communicating with a nozzle and a piezoelectric vibrating body that imparts flexural vibration to the pressure generating chamber, and ejects ink in the pressure generating chamber from the nozzle by vibration of the piezoelectric vibrating body.
A pressure generating chamber forming member that forms the pressure generating chamber; a vibration plate made of a conductive member that forms one wall surface of the pressure generating chamber; and the pressure generating chamber at a position on the vibrating plate facing the pressure generating chamber. A piezoelectric vibrator formed in a region smaller than both of the long side direction and the short side direction, an electrical insulating layer formed so as to overlap with a part of the piezoelectric vibrator, and the piezoelectric vibrator from above An ink jet recording head comprising: an electrode layer formed up to the electrical insulating layer.   2. The ink jet recording head according to claim 1, wherein a part of the piezoelectric vibrating body is formed so as to overlap the electric insulating layer.   2. The ink jet recording head according to claim 1, wherein a part of the electrically insulating layer is formed so as to overlap the piezoelectric vibrating body.   2. The ink jet recording head according to claim 1, wherein the thickness of the electrical insulating layer is substantially the same as the thickness of the piezoelectric vibrator.   2. The ink jet recording head according to claim 1, wherein an adhesion layer is formed on the electrical insulating layer.   6. The ink jet recording head according to claim 5, wherein the adhesion layer is made of Ti, Pt, Cr, or a material containing at least one component thereof.   2. The ink jet recording head according to claim 1, wherein the individual electrode and the terminal electrode are formed on the electrical insulating layer so as to overlap each other.   The surface of the pressure generating chamber forming member opposite to the surface on which the diaphragm is formed is formed with a nozzle plate having a nozzle opening, a reservoir forming substrate having a common ink chamber, and a through hole serving as a flow path. 2. An ink jet recording head according to claim 1, wherein a flow path forming member made of a cover plate is laminated.   2. The ink jet recording head according to claim 1, wherein the diaphragm is a common electrode, and the common electrode is electrically connected to the terminal electrode on the electrical insulating layer.   2. The ink jet recording head according to claim 1, wherein a terminal electrode connected to the individual electrode and a terminal electrode connected to the common electrode are arranged in a line.

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