JP2000052556A - Ink-jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drive all channels simultaneously and enable highspeed printing by forming the ink channel of a wall coupling two diaphragms and a wall where nozzles are set and constituting one of the coupled walls of a shearing mode piezoelectric driving element. SOLUTION: A common piezoelectric driving substrate 24 is constituted with the use of a cover plate of a piezoelectric material in a one-piece structure common to all channels. A common earth electrode 11 is tightly adhered to an entire face in touch with ink channels 4-1 to 4-n each formed of a wall coupling two diaphragms of the common piezoelectric driving substrate 24 and a wall where nozzles are set. Moreover, an electrode pattern having a length approximately half a breadth D of the ink channel 4-1 to 4-n in an arrangement direction is formed by vapor deposition or the like, thereby forming electrodes 10. The electrodes 10 are tightly adhered to the other face. Many shearing mode piezoelectric driving elements 21-1 to 21-n are thus formed in parallel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which a piezoelectric driving element is provided on a part of a wall constituting an ink flow path having a number of parallel nozzles, and the piezoelectric driving element is driven by a driving pulse. The present invention relates to an ink-jet head for discharging ink from an ink jet head.

[0002]

2. Description of the Related Art Various types of ink jet heads for use in ink jet printers have been proposed. One of them is a shear mode ink jet head, which is described in Japanese Patent Application Laid-Open No. 63-247051.

In the ink jet head described in this publication, a large number of ink channels each having an ink discharge nozzle are arranged at a side wall, and a part or the whole of the side wall is made of a piezoelectric material. An electrode to which a drive pulse is applied is formed on the entire surface or a part of the side wall. By applying a drive pulse to the electrode, the side wall is deformed, the pressure in the flow path is changed, and ink droplets are ejected from the nozzle formed at one end of the flow path.

FIGS. 1 and 2 are views showing a conventional example of the ink jet head described in the above publication, and are views for explaining the basic operation. 1 is an ink tube, 2 is a nozzle forming member, 3 is a nozzle, 4 is an ink flow path, 5 is a piezoelectric side wall made of a piezoelectric material, 6 is a cover plate, 7 is an ink supply port, 8 is an ink discharge port, and 9 is a substrate. Reference numeral 10 denotes an electrode. The ink flow path 4 is formed by the piezoelectric side wall 5, the cover plate 6, and the substrate 9. FIG. 1 shows an ink jet head having one ink flow path and one nozzle. In an actual ink jet head, a plurality of ink jet heads are provided between a cover plate 6 and a substrate 9 as shown in FIG. A large number of ink flow paths 4 separated by the piezoelectric side wall 5 are formed in parallel, and one end of the ink flow path 4 is connected to the nozzle 3 formed on the nozzle forming member 2,
Is connected to a slit-shaped ink discharge port 8. The ink flow path 4 is connected to an ink tank (not shown) by an ink tube 1 via an ink supply port 7 adjusted to the pitch of the flow path 4. Piezoelectric side wall 5
A drive pulse voltage is applied between the electrode 10 and the ground electrode 11 which are formed in close contact with the electrodes.

In FIG. 2A, the piezoelectric side wall 5 is composed of piezoelectric side walls 5A and 5B made of two piezoelectric materials having different polarization directions as indicated by arrows. As shown in FIG. 2A, when no drive pulse is applied to the electrode 10, the piezoelectric side walls 5A and 5B do not deform. But Figure 2
As shown in (b), when a drive pulse is applied to the electrode 10, an electric field in a direction perpendicular to the polarization direction of the piezoelectric material causes shear deformation on the joining surfaces of the piezoelectric side walls 5A and 5B, thereby causing a flow. The ink flow path 4 is changed by the pressure change of the path 4.
Is partially discharged from the nozzle 3 and the other portion is discharged to the ink tank through the ink supply port 7.
After the ink is ejected, the ink is supplied to the nozzle from the ink tank through the ink supply port and the flow path 4 by the force due to the capillary action of the nozzle. Further, there is a case where the substrate 9 as shown in FIG. 3 has a structure different from that of the piezoelectric side wall.

[0006]

As described above, the piezoelectric sidewall separating each ink flow path in which a plurality of ink flow paths are arranged in parallel is used to discharge ink droplets as shown in FIG. 2 (b). When the piezoelectric side wall is deformed by the drive voltage pulse, the adjacent channels are also affected, so that all the channels cannot be driven simultaneously. Therefore, a method of driving the channel in three phases has been adopted. That is, the channel CH-1 is driven, and then the channel CH-2 is driven. Next, the channel CH-3 is driven, and the channel CH-1 is driven again. When the ink is ejected by such a driving method, it is necessary to arrange the nozzles as shown in FIG. 4 in consideration of the time delay of the ejection between the phases.

The arrangement of the nozzles is set by calculating the amount of nozzle displacement based on the head feed speed during printing and the ejection delay time. Such a head has a complicated design and structure, and a head having a complicated fine structure poses a manufacturing problem. In addition, since all channels cannot be emitted at the same time, high-speed printing cannot be performed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems in the shear mode ink jet head, and it is possible to drive all the channels simultaneously, to perform high-speed printing, and to easily manufacture. An object of the present invention is to provide an inkjet head.

[0009]

The object of the present invention is as follows.
In an ink jet head provided with a plurality of ink flow channels and ink discharge channels provided with nozzles connected to the ink flow paths, the ink flow paths are formed by two of the partition walls and the two partition walls. This is achieved by an ink jet head formed by a connecting wall and a wall on which the nozzle is formed, wherein at least one of the connecting walls is constituted by a shear mode piezoelectric driving element.

[0010]

FIG. 4 is a sectional view showing an embodiment of an ink jet head according to an embodiment of the present invention.
Is a perspective view thereof. Reference numerals 21-1 and 21-2 denote piezoelectric driving elements also serving as cover plates, 3 denotes nozzles, and 4-1 and 4-
Reference numeral 2 denotes an ink flow path, 9 denotes a substrate, 10 denotes an electrode to which a drive pulse is applied, 11 denotes a ground electrode, and 22-1, 22-2 denote side walls. The side walls 22-1 and 22-2 are formed on the substrate 9 using an integral material.

FIG. 4 shows two ink channels 4-1 and 4-2.
However, in an actual head, a required number of ink flow paths 4-1 4-2... 4-n are provided. As shown in FIG. 4, for example, the ink flow path 4-1 includes the substrate 9, the side walls 22-1, 22-2, and the shear mode piezoelectric driving element 21-.
And 1. The substrate 9, the side wall 22-1, and the like are made of a material such as ceramic or glass, and ink channels 4-1 to 4-2... 4-n are formed by a process such as etching. The electrode 10 to which the driving pulse is applied is desirable because it can be easily formed by pattern deposition. Earth electrode 1
1 can be formed in a similar manner, but it is also possible to provide the substrate 9 with a grounding function.
1 is not always necessary, and is formed as needed.
A protective layer made of an inorganic or organic material is provided on the surface of the electrode as needed. Note that the substrate 9 itself can be used as the ground, and in this case, it is not necessary to provide the ground electrode 11.

Shear mode piezoelectric drive elements 21-1, 21-
Numeral 2 is composed of two piezoelectric members 21A and 21B made of two piezoelectric materials whose polarization directions are different from each other as indicated by arrows, ie, whose polarization directions are opposite to each other. Each of the piezoelectric members 21A and 21B has an electrode 10 to which a drive pulse is applied on its upper surface and a ground electrode 11 on its lower surface, so that shear mode piezoelectric drive elements 21-1, 21-21 operated by the drive pulse. 2 are configured. FIG. 4 shows a state in which no drive pulse is applied to the electrode 10, and the shear mode piezoelectric drive elements 21-1 and 21-2 are not deformed. As shown in FIG. 6, when a drive pulse is applied to the electrode 10, shear deformation occurs in the joint surfaces of the shear mode piezoelectric drive elements 21-1 and 21-2, and the ink flow paths 4-1 and 4-2 are formed.
Pressure is applied to the ink inside. Ink channels 4-1 and 4
-2 is partially discharged from the nozzle 3,
The other part is discharged to the ink tank through the ink supply port.

Shear mode piezoelectric drive elements 21-1, 21
2 does not form a partition wall between the ink flow paths 4-1 and 4-2, but instead forms partition walls 22-1, 22-2, and 22-3.
To form a wall that connects Since the shear mode piezoelectric driving elements 21-1 and 21-2 move vertically in FIG. 5, they do not affect adjacent channels, and therefore each channel can be driven completely independently at the same time. With this configuration, all channels can be driven simultaneously and ink droplets can be ejected from the nozzles of all channels, so that high-speed recording is possible.

In addition to the embodiment of the present invention described above,
As shown in FIG. 7, the shear mode piezoelectric driving elements 21-1, 2-1,
1-2 can be provided not on the cover plate 6 side but on the substrate 9 side. Shear mode piezoelectric drive element 2
1-1, 21-2 and side walls 22-1, 22-1, 22,
3 is formed of the same piezoelectric material, and ink channels 4-1 and 4-2 are formed by etching.
Polarized shear mode piezoelectric drive elements 21-1 and 21-2
1-2 are formed.

As shown in FIG. 8, a common piezoelectric driving substrate 24 may be formed by using a cover plate of an integral structure common to all channels made of a piezoelectric material and applying polarization in the direction shown by the arrow. it can. A common ground electrode 11 is adhered to the entire surface of the common piezoelectric drive substrate 24 that is in contact with the ink flow paths 4-1, 4-2,..., 4-n. An electrode formed by vapor deposition or the like with an electrode pattern having a lateral width of each of the ink flow paths 4-1,..., 4-n, that is, about half the width D of the ink flow paths in the parallel direction. 10 are closely attached.

With such a configuration, the ink flow path 4-
A number of parallel shear mode piezoelectric drive elements corresponding to 1,4-2... 4-n are formed. When the common earth electrode 11 is grounded and a drive pulse voltage is applied to the electrode 10, the portions of the common piezoelectric drive substrate 24 corresponding to the respective channels are independently deformed as indicated by the dotted lines 24a, and from the respective channels in the same manner as described above. To eject ink droplets. As in this embodiment, the ink jet head having the structure using the common piezoelectric driving substrate 24 has many advantages in manufacturing, such as simplification of processes such as polarization processing of a piezoelectric material, formation of an ink flow path, and deposition of electrodes. Having.

FIGS. 9, 10 and 11 show a embodied embodiment.

The substrate 9 in FIG.
1, 4-2 and 4-3 are formed, and a nozzle 3 is formed in each ink flow path. The common piezoelectric drive substrate 24 is polarized in one direction as shown by an arrow, and an electrode 10 to which a drive pulse is applied is formed on the upper surface, and a ground electrode 11 is formed on the other surface in close contact. On the surface of the ground electrode 11, a protective layer 25 made of an inorganic or organic material such as ceramics for protecting the ground electrode 11 from ink is provided. The electrode 10 to which the drive pulse is applied is as shown in the figure.
The piezoelectric material is formed on the upper surface of the piezoelectric driving element corresponding to almost half the area of the ink flow path 4-1 and the like. When a driving pulse is applied to such an electrode, the piezoelectric material is deformed and is discharged from the nozzle 3-1. Discharge ink.

FIG. 10 shows an embodiment in which ink flow paths are formed on both sides of the substrate 9 and a common piezoelectric driving substrate 24 is provided on both sides of the substrate 9. It has the advantage that it can be realized.

FIG. 11 shows an embodiment in which a piezoelectric material polarized in two opposite directions is used as the common piezoelectric driving substrate 24. In this embodiment, the ink flow paths 4-1 and 4-2.
An electrode 10 to which a drive pulse is applied is formed on a portion of the common piezoelectric substrate corresponding to almost the entire area of the substrate. With such a configuration, the driving efficiency of the piezoelectric driving element by the driving pulse is increased, and the ink is reliably ejected.

In the embodiment shown in FIGS. 4 to 11, it is not always necessary to use a piezoelectric material as the material of the substrate 9 for forming the flow path of the ink jet head. A flow path can be easily formed in the process. Further, the electrode 10 to which the drive voltage is applied only needs to perform pattern deposition from one direction,
The formation process is easy. Furthermore, the ground electrode 1 on the back
The electrode 1 can also be formed by an easy and inexpensive technique such as depositing an electrode material on the entire surface or coating the entire surface with a conductive material. It is desirable that a protective layer 25 be laminated on a surface that comes into contact with the ink (for example, the surface of the ground electrode 11). In these manufacturing steps, inexpensive materials are used, and the cost of the steps is small, so that an inexpensive inkjet head can be provided.

[0022]

In the shear mode ink jet head, since the adjacent channel is affected by the driving of one channel, it is impossible to drive all the channels simultaneously. Further, when manufacturing these ink jet heads, material costs and manufacturing costs were high and expensive, but since the present invention can drive all channels simultaneously and the manufacturing process is simple,
An inexpensive inkjet head capable of high-speed recording can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a conventional inkjet head.

FIG. 2 is a diagram showing a configuration of a conventional multi-channel ink jet head.

FIG. 3 is a diagram showing an arrangement of nozzles of a conventional multi-channel inkjet head.

FIG. 4 is a diagram illustrating a configuration of an inkjet head according to an embodiment of the present invention.

FIG. 5 is a perspective view of the ink jet head shown in FIG.

FIG. 6 is a diagram showing the operation of the inkjet head shown in FIGS. 4 and 5;

FIG. 7 is a diagram showing a configuration of an inkjet head according to another embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of an inkjet head according to still another embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of an inkjet head according to still another embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of an inkjet head according to still another embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of an ink jet head according to still another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Ink tube 2 Nozzle formation member 3 Nozzle 4,4-1,4-2 ... 4-n Ink flow path 5,22-1,22-2 ... 22-n Side wall 6 Cover plate 7 Ink supply port Reference Signs List 8 ink discharge port 9 substrate 10 electrode 11 earth electrode 21-1, 21-2... 21-n shear mode piezoelectric drive element 24 common piezoelectric drive board

Claims (6)

[Claims] An ink jet head provided with a plurality of ink discharge channels each including an ink flow path and a nozzle connected to the ink flow path, separated by a partition wall.
The ink flow path is formed by two partition walls, a wall connecting the two partition walls, and a wall on which the nozzle is formed, and at least one of the connecting walls is configured by a shear mode piezoelectric driving element. Characteristic inkjet head. 2. The ink jet head according to claim 1, wherein the shear mode piezoelectric driving element is formed as a member separate from a cover plate or a lower substrate of the ink jet head. 3. The ink-jet head according to claim 1, wherein the cover plate and / or the lower substrate of the ink-jet head is made of a piezoelectric material forming the shear mode piezoelectric driving element. 4. The ink jet head according to claim 1, wherein the shear mode piezoelectric driving element faces the ink flow path via a protective layer. 5. A shear mode piezoelectric drive element is provided in which an electrode to which a drive pulse is applied is provided in a part of an area occupied by the ink flow path on a common substrate made of a piezoelectric material having a polarization direction in one direction. The ink jet head according to claim 2 or 3, wherein the ink jet head is used. 6. A piezoelectric material having polarization directions opposite to each other corresponding to the ink flow path, and an electrode to which a drive pulse is applied is provided over substantially the entire area indicated by the ink flow path. The inkjet head according to claim 2 or 3, wherein