JP2000158654A - Ink jet printer head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve an area sufficient for a large current by utilizing a nozzle plate as an electrode section of a side of a common electrode without complicating a structure of a wiring pattern. SOLUTION: This printer head comprises a common electrode (an electrode pattern 18B of a negative electrode) which is provided to a cover plate 17 consisting of a piezoelectric actuator and is commonly used by all of the ink chambers and individual electrodes (an electrode pattern 18A of a positive electrode) respectively provided on the cover plate 17. A nozzle plate 32 is made from a metallic material or a conductive material and is electrically connected to the common electrode. The piezoelectric actuator (cover plate 17) is driven by applying a driving voltage across the common electrode and each of the individual electrode, then a pressure in an ink chamber is selectively varied, thereby ejecting ink in the ink chamber through a nozzle 32a on the nozzle plate 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink jet printer head used for an ink jet printer.

[0002]

2. Description of the Related Art As an ink jet printer head used in an ink jet printer, for example, a plurality of ink jet heads are provided in parallel, and each ink jet head has a plurality of ink chambers partitioned by a plurality of partition walls. A ceramic cavity plate,
A nozzle plate having nozzles corresponding to the respective ink chambers is joined to one end of a head body constituted by a cover plate comprising a piezoelectric actuator joined to the cavity plate. There is known an apparatus in which pressure fluctuation is caused to cause ink in an ink chamber to be ejected from nozzles of a nozzle plate. In such an ink jet head, a cover plate that causes a pressure fluctuation for ink ejection in the ink chamber includes:
A common electrode commonly used for all ink chambers, and an individual electrode provided separately, and a drive voltage is applied between the common electrode and the individual electrode to drive and deform the cover plate. In some cases, the pressure in the ink chamber is selectively changed so that the ink in the ink chamber is ejected through the nozzles of the nozzle plate.

As one of the piezoelectric actuators used for such a cover plate, a laminated piezoelectric actuator is known, and such a laminated piezoelectric actuator is formed on a piezoelectric material formed in a sheet shape. The electrode patterns of the positive and negative electrodes alternately arranged at predetermined intervals are screen-printed, and a piezoelectric material is layered on this electrode pattern. After repeating the above, a binder removal and firing treatment is performed, and then, the deformed portions in the piezoelectric actuator are each made independent,
It is manufactured through a process of providing a plurality of notches in the cavity plate. With such a configuration, a plurality of deformed portions of the piezoelectric actuator can be made to correspond to each of the plurality of ink chambers, and ink can be ejected for each ink chamber.

More specifically, as shown in FIG. 3, for example, in an ink jet printer head 1, a plurality of piezoelectric ink jet heads 2 are arranged in parallel on the front surface of a first ink flow path plate 3.

The first ink flow path plate 3 is a plate-like member formed of aluminum or magnesium. A heater 4 having a stainless steel pattern sandwiched between polyimide films is attached to the front surface, and an ink (not shown) is mounted to the back surface. An outward path 5 of the ink supplied from the tank is formed. The first ink passage plate 3 has a first through hole 7 penetrating from the front surface to the back surface and communicating with the outward path 5.
Is formed, and the ink supplied to the outward path 5 is supplied to the front side through the first through hole 7.

Further, the first ink flow path plate 3
The second ink flow path plate 9 is attached. The second ink flow path plate 9 is also a plate-shaped member made of aluminum or magnesium, and has a back path 8 for discharging ink to the ink tank on the back surface.
Are formed.

On the other hand, the ink jet head 2 includes a base plate 10, a cavity plate 12, a nozzle plate 16, and a cover plate 17 made of a piezoelectric actuator.

The base plate 10 is a plate-like member made of aluminum or magnesium, and has a second through hole 11 communicating with the first through hole 7 of the first ink flow path plate 3. I have. The base plate 10 has a back surface bonded to the first ink flow path plate 3 with an adhesive, and a front surface of the cavity plate 1
2 is also adhered by an adhesive, and a cover plate 17 is further adhered thereon.

The cavity plate 12 is a sintered body of ceramic, and has a plurality of ink chambers 13 whose front sides are open, a partition wall 14 for partitioning each of the ink chambers 13, and
An ink reservoir 15 communicating with the ink chambers 13 on the front side and communicating with the second through holes 11 on the rear side is formed.

The nozzle plate 16 is a sheet-like member made of polyimide, and has a plurality of nozzles 16a penetrating from the front side to the back side. The ink chamber 13 communicates with the ink reservoir 15 on the upper surface side, and gradually decreases in width toward the lower surface side, and opens at the lower end surface. The nozzle plate 16 is adhered to the lower end surface thereof with an adhesive so that the positions of the openings and the nozzles 16a coincide with each other. Heretofore, there has been known a nozzle plate using a metal material in order to obtain processing accuracy of the nozzle.

The cover plate 17 is provided for each of the ink chambers 1.
3 is a laminated piezoelectric actuator that is attached so that the front surface (open surface) of the piezoelectric ceramic 3 is closed, and a plurality of piezoelectric ceramic layers made of a lead zirconate titanate (PZT) -based ceramic material having a piezoelectric / electrostrictive effect are laminated. At the same time, the electrode patterns 18A and 18B of the positive electrode and the negative electrode such as silver palladium are screen-printed between the piezoelectric ceramic layers.
Are formed.

The electrode patterns 18A and 18B are connected to a power supply end (not shown). The power supply end is connected to the drive I through a flexible printed circuit board 20.
It is connected to C21. Further, the drive IC 2
Reference numeral 1 is connected via a flexible printed board 20 to a main board provided with a CPU (not shown) and the like. Therefore, the drive IC 21 is driven according to the drive signal output from the main board, and furthermore, the drive IC 2
When the driving voltage is supplied to the electrode pattern 18A from the nozzle plate 1, the piezoelectric ceramic layer is displaced, and the pressure in the ink chamber 13 formed by the cavity plate 12 is changed.
The ink is ejected from 6a.

Such an ink jetting operation is simultaneously performed by the respective piezoelectric type ink jet heads 2, and the entire head of the line type ink jet printer configured as described above is driven by a swing mechanism (not shown). Since it swings in the direction of arrow A, high-speed printing is performed on the recording paper P in line units.

In the structure described above, the electrode pattern 18A of the positive electrode functions as an individual electrode individually provided on the cover plate 17, while the electrode pattern 18B of the negative electrode is common to all the ink chambers 13. Since the electrode pattern 18B of the negative electrode functions as a common electrode to be used, the electrode pattern 18B of the negative electrode is gathered at one collective electrode portion and grounded.

[0015]

In recent years, there has been a demand for miniaturization of the head. However, if the size of the collective electrode portion is correspondingly reduced, a large amount of current flows when the ink jet head is driven. Therefore, there is a possibility that the collective electrode portion is burned. Therefore, the arrangement of the collective electrode portion for such a common electrode has become a problem. In particular, when the head is long, a larger amount of current flows, so that the tendency is remarkable.

The present invention has been made in view of the above-described circumstances. By using a nozzle plate as an electrode portion on the common electrode side, a large-capacity current can be passed without complicating the wiring structure. It is an object of the present invention to provide an ink jet printer head capable of securing a sufficient area.

[0017]

According to a first aspect of the present invention, there is provided a head body in which a plurality of ink chambers are formed, a nozzle plate having nozzles communicating with the ink chambers and joined to the head body, It is arranged to correspond to the ink chamber,
A pressure generating member that varies the pressure in the ink chamber, a common electrode provided in the pressure generating member and commonly used for all ink chambers, and an individual electrode individually provided in the pressure generating member, An ink jet printer that applies a drive voltage between the common electrode and the individual electrode to drive the pressure generating member to selectively change the pressure in the ink chamber, and eject ink in the ink chamber through the nozzles of the nozzle plate. The nozzle plate is formed of a metal material or a conductive material and is electrically connected to the common electrode.

According to the first aspect of the present invention, the drive between the common electrode provided on the pressure generating member and commonly used for all ink chambers and the individual electrode individually provided on the pressure generating member. When a voltage is applied, the pressure generating member is driven to selectively fluctuate the pressure in the ink chamber, and ink in the ink chamber is ejected through the nozzles of the nozzle plate. At this time, since the nozzle plate formed of a metal material or a conductive material is electrically connected to the common electrode, the nozzle plate having a sufficient area for flowing a large amount of current is commonly used. A large-capacity current, which is a set of currents flowing through the electrodes, flows, and there is no problem such as burning of the electrode portions.

According to a second aspect of the present invention, in the ink jet printer head of the first aspect, the pressure generating member comprises:
This is a piezoelectric actuator made of a piezoelectric material.

According to the second aspect of the present invention, since the pressure generating member is a piezoelectric actuator made of a piezoelectric material,
When a drive voltage is applied between the common electrode and the individual electrodes,
When the piezoelectric actuator (pressure generating member) is deformed, the pressure in the ink chamber is selectively changed, and the ink in the ink chamber is ejected through the nozzles of the nozzle plate.

According to a third aspect of the present invention, in the ink jet printer head according to the first or second aspect, the common electrodes and the individual electrodes are alternately arranged along the longitudinal direction of the ink chamber, and the common electrode is arranged on the nozzle plate side. Is extended to the vicinity of the nozzle plate and is electrically connected.

According to the third aspect of the present invention, of the common electrodes and the individual electrodes alternately arranged along the longitudinal direction of the ink chamber, one end of the common electrode on the nozzle plate side extends to the vicinity of the nozzle plate. Therefore, it is easily electrically connected to the nozzle plate, and a large amount of current can flow through the nozzle plate.

According to a fourth aspect of the present invention, in the ink jet printer head according to any one of the first to third aspects, the common electrode and the individual electrode are formed by vapor deposition, and a nozzle is provided at one end of the head body. The plate is connected by a conductive adhesive layer, and one end of the common electrode extending from the pressure generating member is electrically connected to the nozzle plate via the conductive adhesive layer.

According to the fourth aspect of the present invention, the common electrode and the individual electrode are formed by vapor deposition, and the nozzle plate is connected to one end of the head body by the conductive adhesive layer. The one end of the common electrode extending from the pressure generating member via the second member is electrically connected to the nozzle plate with a simple wiring structure.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The basic structure of an ink jet printer head according to this embodiment is the same as that shown in FIG. The same components are denoted by the same reference numerals, and different portions from those shown in FIG. 3 and portions not described in the description of FIG. 3 will be described.

FIG. 1 is a perspective view showing a schematic configuration of one of the plurality of ink jet heads in an ink jet printer head in which a plurality of ink jet heads according to the present invention are juxtaposed, and FIG. FIG. 2 is a cross-sectional view illustrating a schematic configuration of an inkjet.

As shown in FIG. 1, one end surface of a head body 31 in which a plurality of ink chambers 13 are formed is provided with the ink chambers 1.
The nozzle plate 32 having a nozzle 32a communicating with the nozzle 3 and formed of a metal material or a conductive material is joined via a conductive adhesive layer 33 formed of an adhesive containing a conductive substance. I have.

As shown in FIG. 2, the head main body 31 has a cover plate 17 made of a piezoelectric actuator joined to a cavity plate 12 in which a plurality of ink chambers 13 are formed so as to cover the ink chambers 13. Things. Therefore, on the upper side of the head main body 31, a cover plate 17 which is a pressure generating member for changing the pressure in the ink chamber 13 so as to correspond to each ink chamber 13 is provided.
Is arranged. Since the cover plate 17 generates heat and expands thermally when a drive voltage for ejecting ink is applied, the cavity plate 12 is preferably formed using a material having a coefficient of thermal expansion substantially equal to the coefficient of thermal expansion. .

The cover plate 17 is made of a lead zirconate titanate (PZT) -based ceramic material (piezoelectric material). The first piezoelectric ceramic layer 41, the second piezoelectric ceramic layer 42, and the third Piezoelectric ceramic layer 43,
The fourth piezoelectric ceramic layer 44 and the fifth piezoelectric ceramic layer 45 are stacked in this order.

The first to fourth piezoelectric ceramic layers 41 to 41
44, an electrode pattern 18A of a positive electrode extending in the longitudinal direction of the ink chamber 13 is provided at a position corresponding to the center of each ink chamber 13, and the partition wall 14 is provided at a position corresponding to each partition wall 14.
The electrode patterns 18B of the negative electrodes extending in the longitudinal direction are formed. That is, the electrode pattern 18 of the positive electrode
A and the electrode pattern 18B of the negative electrode are alternately arranged along the longitudinal direction of the ink chamber. Here, the electrode pattern 18A of the positive electrode functions as an individual electrode individually provided on the cover plate 17, and the electrode pattern 1A of the negative electrode is used.
8B functions as a common electrode commonly used by all the ink chambers 13. The electrode patterns 18A and 18B are formed by masking the surface of the cover plate 17 with a mask member having a predetermined pattern and vapor-depositing using an electrode forming material such as chromium, nickel, or gold. It is also possible to form by performing screen printing instead of vapor deposition.

The electrode pattern 18A for the positive electrode and the electrode pattern 18B for the negative electrode are formed of the respective piezoelectric ceramic layers 41-41.
44, the piezoelectric ceramic layers 41 to 44 are stacked so as to overlap each other in the stacking direction of the piezoelectric ceramic layers 41 to 44. Each of the piezoelectric ceramic layers 41 to 44 is polarized in the stacking direction as shown in FIG. Have been.

The electrode pattern 18A of each positive electrode includes:
As shown in FIG. 1, while the drive circuit 51 is electrically connected, the electrode pattern 18 </ b> B of the negative electrode has one end on the nozzle plate 32 side extending to the vicinity of the nozzle plate 32, and is connected to the nozzle plate 32. Conductive adhesive layer 33
And a driving voltage from a driving circuit 51 is applied to the electrode pattern 18A of the positive electrode. Here, in particular, the conductive adhesive layer 33
Is effectively used to electrically connect the electrode pattern 18B of the negative electrode to the nozzle plate 32, so that there is no need to provide special wiring to connect them, and a simple wiring structure is used. Thus, their electrical connection becomes possible.

By doing so, the nozzle plate 32
Can be used as a collective electrode portion where the electrode pattern 18B of the negative electrode, which is a common electrode, is collected, and the layout problem of the common electrode (electrode pattern 18B of the negative electrode) and its collective electrode portion is avoided. At the same time, the head can withstand heat generation, so that there is no effect even if a large amount of current flows, and the head can be reduced in size.

Therefore, the positive electrode pattern 18A
The driving circuit 51 is provided between the driving circuit 51 and the negative electrode pattern 18B.
When a driving voltage is applied based on predetermined print data, the polarization of the piezoelectric ceramic layers 41 to 44 indicated by arrows in FIG. 2 is caused between the positive electrode pattern 18A and the negative electrode pattern 18B. An electric field substantially orthogonal to the direction is generated. Accordingly, the first to fourth piezoelectric ceramic layers 41 to 44 are deformed so as to be convex toward the ink chamber in the share mode based on the piezoelectric / electrostrictive effect. still,
The “share mode” is a deformation mode that occurs when a voltage is applied to the polarized piezoelectric actuator in a direction perpendicular to the polarization direction, and the piezoelectric actuator is deformed in a direction parallel to the polarization direction. This is a mode of deformation caused by the thickness slip of the actuator.

Therefore, at the position corresponding to the ink chamber 13, the first to fourth piezoelectric ceramic layers 41 to 44 are provided.
A large displacement is obtained by the share mode, and the pressure in the ink chamber 13 is selectively changed to reduce the volume of the ink chamber 13, so that ink is ejected toward the recording paper through the nozzles 32a of the nozzle plate 32, Printing of characters and the like is performed.

In the above embodiment, the common electrode (positive electrode pattern 18A) and the individual electrodes (negative electrode electrode pattern 18B) are alternately arranged on the cover plate 17 (pressure generating member) and deformed in the shear mode. Although the present invention has been described with the use of a piezoelectric actuator, the present invention is not limited to this. The present invention can also be applied to a piezoelectric actuator that deforms in another mode. For example, the present invention can be applied not only to those employing a piezoelectric actuator that deforms in the expansion / contraction mode, but also to provide a common electrode in the outermost layer so as to cover the surface of the piezoelectric actuator, and to deform in a combined mode of the shear mode and the unimorph mode. The present invention is also applicable to those employing an actuator. Note that the “stretching mode” is a mode of deformation that occurs in a polarized piezoelectric body when an electric field is applied in parallel to the polarization direction of the piezoelectric body, and the piezoelectric body extends in a direction parallel to the polarization direction. It refers to a deformation mode caused by the expansion and contraction of itself. `` Unimorph mode '' means that the piezoelectric actuator expands and contracts in the plane direction when an elastic body is fixed to one of the planes perpendicular to the polarization of the polarized piezoelectric body and an electric field is applied in parallel with the polarization direction. It refers to a mode of bending deformation caused by the elastic body acting to restrain it.

Further, in the above-described embodiment, the description has been given of an example in which the pressure generating member is applied to an ink jet printer head using a piezoelectric actuator having a property of mechanically deforming when a voltage is applied. Also, the present invention can be applied to a head (thermal ink jet system) having an electric-heat conversion means.

Further, in the above embodiment, the ink jet head of the push-in type has been described, but the relationship of the polarization direction in the cover plate on which the piezoelectric ceramic layers are laminated is reversed so that the piezoelectric ceramic layers are reversed. It can be applied to a pull-down type by deforming in the direction, that is, a direction to increase the volume of the ink chamber. In addition to a laminated piezoelectric actuator, a piezoelectric formed by a single layer The present invention is also applicable to those using an actuator.

[0039]

The present invention is embodied in the form described above, and has the following effects.

According to the first aspect of the present invention, the nozzle plate is formed using a metal material or a conductive material, and the nozzle plate is electrically connected to the common electrode.
By using the nozzle plate as the collective electrode portion where the common electrode for applying the drive voltage gathers, the common electrode and its associated collective electrode portion are not specially arranged, and the wiring structure is complicated. Without doing
A large amount of current can be passed, which is advantageous in realizing miniaturization of the head.

According to the second aspect of the present invention, since the pressure generating member is a piezoelectric actuator made of a piezoelectric material, a driving voltage is applied between the common electrode and the individual electrodes, so that the piezoelectric actuator (pressure generating member) is formed. The ink in the ink chamber can be ejected through the nozzles of the nozzle plate by selectively deforming and changing the pressure in the ink chamber.

According to a third aspect of the present invention, of the common electrodes and the individual electrodes alternately arranged along the longitudinal direction of the ink chamber, one end of the common electrode on the nozzle plate side is extended to the vicinity of the nozzle plate. Since the nozzle plate is electrically connected to the nozzle plate, the nozzle plate can be easily used as a common electrode that allows a large amount of current to flow with a simple wiring structure.

According to a fourth aspect of the present invention, a common electrode and an individual electrode are formed by vapor deposition, and a nozzle plate is connected to one end of a head main body by a conductive adhesive layer, and the nozzle plate is connected via the conductive adhesive layer. Since one end of the common electrode extending from the pressure generating member is electrically connected to the nozzle plate, one end of the common electrode extending from the pressure generating member can be connected without a special wiring structure. It can be easily electrically connected to the nozzle plate.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of one of a plurality of inkjet heads in an inkjet printer head having a plurality of inkjet heads according to the present invention arranged in parallel.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of an inkjet according to the present invention.

FIG. 3 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Cavity plate 13 Ink chamber 17 Cover plate 18A Electrode pattern of positive electrode 18B Electrode pattern of negative electrode 31 Head body 32 Nozzle plate 32a Nozzle 41-44 Piezoelectric ceramic layer 51 Drive circuit

Claims (4)

[Claims] A head body in which a plurality of ink chambers are formed; a nozzle plate having nozzles communicating with the ink chambers and joined to the head body; A pressure generating member that varies the pressure in the ink chamber, a common electrode provided in the pressure generating member and commonly used for all ink chambers, and an individual electrode individually provided in the pressure generating member, An ink jet printer that applies a drive voltage between the common electrode and the individual electrode to drive the pressure generating member to selectively change the pressure in the ink chamber, and eject ink in the ink chamber through the nozzles of the nozzle plate. The nozzle plate is formed of a metal material or a conductive material, and is electrically connected to the common electrode. Inkjet printer head. 2. The ink jet printer head according to claim 1, wherein said pressure generating member is a piezoelectric actuator made of a piezoelectric material. 3. The common electrode and the individual electrode are alternately arranged along the longitudinal direction of the ink chamber, and one end of the common electrode on the nozzle plate side extends to near the nozzle plate and is electrically connected. The ink jet printer head according to claim 1 or 2. 4. A method according to claim 1, wherein the common electrode and the individual electrode are formed by vapor deposition, a nozzle plate is connected to one end of the head body by a conductive adhesive layer, and extends from the pressure generating member. 4. The ink jet printer head according to claim 1, wherein one end of said common electrode is electrically connected to a nozzle plate via a conductive adhesive layer.