JPH1016216A - Ink jet head and printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of man-hours for manufacture of an ink jet head to enhance productivity. SOLUTION: A slit 4 is formed to a nozzle plate 5 so as to straddle a plurality of grooves 7 for pressure chambers of piezoelectric elements 2. The nozzle plate 5 equipped with this slit 4 is bonded and fixed to one end sides of the piezoelectric elements 2. Dummy grooves 8 are respectively formed on both adjacent sides of the grooves 7 for the presssure chambers. Positive voltage is applied to the electrode 9b formed to the inner wall of the specific groove 7 for the pressure chamber and negative voltage is applied to the electrodes 10a, 10b formed to the inner walls of both adjacent dummy grooves 8 to deform the side wall of a specific pressure chamber 15 to generate a pressure wave in the ink within the specific pressure chamber 15. Ink is emitted from the slit 4 by this pressure wave.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head for forming characters and images by dot matrix by spraying ink on a sheet, and a printer having the ink jet head.

[0001]

2. Description of the Related Art Conventionally, an ink jet head of this type has been known as shown in FIG.

In the ink jet head 30, a plurality of grooves for a plurality of pressure chambers 32 are formed in a piezoelectric body 31, an upper opening thereof is closed with a flexible film 33, one end is closed with a nozzle plate 34, and the other end is closed. The side is connected to an ink pool (not shown). Electrodes 36 (36a, 36b) are arranged at the upper end of the side wall 35, respectively.
An electrode 37 paired with 6 is arranged on the bottom surface 31 a of the piezoelectric body 31.

The ink-jet head 30 first discharges ink in a specific pressure chamber 32a among a plurality of pressure chambers 32 formed in a piezoelectric body 31.
A positive voltage is applied to the electrodes 36a on both sides of the, and a negative voltage is further applied to the electrodes 36b on both sides thereof to deform the piezoelectric body 31 and the flexible film 33 as shown by phantom lines in the figure.
The volume of the specific pressure chamber 32a is increased, and ink is sucked into the interior. Next, the inkjet head 30 sharply cuts off the applied voltage or switches the polarity of the applied voltage, restores or reduces the volume of the specific pressure chamber 32a, and sharply increases the internal pressure of the pressure chamber 32a. Ink is ejected from the nozzle 38.

In the ink jet head 30, since the two pressure chambers 32 on both sides of the specific pressure chamber 32a do not discharge ink, at the same time when the ink is discharged from the other pressure chamber 32, at least the specific pressure chamber 32a is moved from the specific pressure chamber 32a. It is necessary to specify the pressure chamber 32 which is separated by two or more (for example, see Japanese Patent Application Laid-Open No. 5-338147).

Further, as a conventional ink jet head,
The one shown in FIG. 6 is known.

When the ink jet head 40 ejects ink from a specific pressure chamber 41a, a voltage is applied to an electrode 42 disposed on the inner wall of the specific pressure chamber 41a, and the voltage is applied to the inner wall of a pressure chamber 41b on both sides thereof. Electrode 43
Is grounded, the side wall 44 of the specific pressure chamber 41a is deformed as shown by the imaginary line, and the internal pressure of the specific pressure chamber 41a is rapidly increased, so that the ink is ejected from the nozzle 45 of the specific pressure chamber 41a. (For example,
See JP-A-63-252750).

[0007]

However, in the conventional ink jet heads 30 and 40, a large number of fine and uniform round nozzles 38 and 45 are formed in the nozzle plates 34 and 46 at a uniform pitch. Therefore, much trouble was required to process the nozzle plates 34 and 46. In addition, the conventional inkjet heads 30, 4
Reference numeral 0 indicates that the nozzle plates 34 and 46 having such minute nozzles 38 and 45 are bonded to the piezoelectric bodies 31 and 47, and the holes of the minute nozzles 38 and 45 are pinched with an adhesive. In order to prevent this, the amount of the adhesive must be adjusted, and the nozzle plates 34 and 46 need to be accurately adhered to the grooves for the pressure chambers 32 and 41 of the piezoelectric bodies 31 and 47. The production of 40 was troublesome.

Therefore, the ink jet heads 30, 4
Accordingly, it has been desired to provide a technology that can facilitate the manufacture of a printer including the inkjet heads 30 and 40 and improve the productivity.

The present invention has been devised to meet such a demand.

[0010]

According to the present invention, there is provided an ink jet head in which a plurality of pressure chambers into which ink is introduced are arranged in parallel, and ink is ejected from nozzles of a nozzle plate fixed to one end of the pressure chamber. The plate nozzle is a slit extending over the plurality of pressure chambers.

The present invention also provides an ink jet head in which a plurality of pressure chambers into which ink has been introduced are arranged in parallel, and the ink is ejected from nozzles of a nozzle plate fixed to one end of the pressure chamber. A piezoelectric body having a pressure chamber groove, a piezoelectric body operation control unit that applies a voltage to the piezoelectric body and pressurizes a specific pressure chamber, and a nozzle plate having a nozzle slit extending over the plurality of pressure chambers, It is characterized by having.

According to the present invention, a plurality of pressure chambers into which ink is introduced are arranged in parallel, and the pressure chambers are formed in an ink jet head which discharges ink from nozzles of a nozzle plate fixed to one end of the pressure chambers. A piezoelectric body having a pressure chamber groove and a dummy groove located on both sides of the pressure chamber groove, a piezoelectric body operation control means for applying a voltage to the piezoelectric body and pressurizing a specific pressure chamber, A nozzle plate having a slit for the nozzle over the pressure chamber.

Further, in the ink jet head according to the present invention, the piezoelectric body operation control means may include electrodes provided separately on inner walls of the pressure chamber groove and the dummy groove of the piezoelectric body, and an electrode on the pressure chamber groove side. And a controller for applying voltages having different polarities to the dummy groove side electrode and the electrode on the dummy groove side.

Further, the ink jet head according to the present invention is characterized in that the electrodes are covered with an insulating film.

Further, a printer according to the present invention includes the above-described ink jet head, and sheet feeding means for feeding a sheet to the ink jet head.

[0016]

An embodiment of the present invention will be described below in detail with reference to the drawings. (Inkjet Head) FIG. 1 is an external perspective view of an inkjet head 1 according to the present embodiment. Also, FIG.
FIG. 2 is a front view (an arrow A direction in FIG. 1) of the inkjet head 1 partially enlarged.

In these drawings, the ink jet head 1 has a top plate 3 attached to the upper surface of a piezoelectric element block (piezoelectric body) 2 and a nozzle plate 5 provided with a slit 4 at the front end of the piezoelectric element block 2. The ink pool 6 is attached to the upper rear end of the piezoelectric element block 2.

The piezoelectric element block 2 is formed with pressure chamber grooves 7 communicating with the ink pool 6 and dummy grooves 8 not communicating with the ink pool 6 alternately. The pressure chamber groove 7 and the dummy groove 8 can be formed by, for example, a single blade or a multi-blade dicing saw superposed at a predetermined pitch. In this embodiment, the groove width of the pressure chamber groove 7 is 60 μm, and the groove width of the dummy groove 8 is 30 μm.
m, and the pitch of the pressure chamber grooves 7 is 169 μm.

The pressure chamber groove 7 and the dummy groove 8
Aluminum and copper alloy electrodes 9 and 10
(9a, 9b ... 10a, 10b) are formed by sputtering or the like. Next, after forming the electrodes 9 and 10,
The upper surface of the side wall 11 between the pressure chamber groove 7 and the dummy groove 8 is polished so that conduction between the electrodes 9 and 10 is eliminated. After that, an insulating film 12 covering the electrodes 9 and 10 is formed. Each of the electrodes 9 and 10 includes a control unit (CPU) 13 that controls the energization of the electrodes 9 and 10.
Connected to The electrodes 9 and 10 and the control unit 13 constitute a piezoelectric body operation control unit 14.

Here, the reason why the electrodes 9 and 10 are covered with the insulating film 12 is that the commonly used ink is water-based and the ink is somewhat conductive.
If the electrode 9 is not covered, electricity flows in the ink when the electrode 9 is energized, and the ink undergoes electrolysis, and the pressure chamber 15
This is because a precipitate is formed inside the ink jet head, and the precipitate may clog the nozzle, making it difficult to perform accurate printing or the like, and lowering the reliability of the ink jet head 1. Therefore, if the electrodes 9 and 10 are covered with the insulating film 12 as in this embodiment, the reliability of the ink jet head 1 can be improved.

As for the properties of the insulating film 12 in contact with the ink, it is desired that the insulating film 12 has good hydrophilicity and good ink resistance in order to make the characteristics of the ink jet head 1 excellent. Therefore, in the present embodiment, the insulating film 12 made of a silicon compound is formed by chemical vapor deposition (CVD).

The top plate 3 adhered to the upper surface of the piezoelectric element block 2 closes the upper openings of the pressure chamber grooves 7 and the dummy grooves 8, and preferably has low rigidity in view of the characteristics of the ink jet head 1. . Therefore, in the present embodiment, a polyimide film having a thickness of 75 μm was used. In this manner, the pressure chamber 15 is formed by closing the upper opening of the pressure chamber groove 7 of the piezoelectric element block 2 with the top plate 3.

The nozzle plate 5 attached to the front end of the piezoelectric element block 2 has slits 4 extending over substantially the entire width of the piezoelectric element block 2, that is, the slits 4 extending over the pressure chamber grooves 7 formed in the piezoelectric element block 2. A slit 4 is formed.
In the present embodiment, the width of the slit 4 is set to 30 μm in consideration of the groove width of the pressure chamber groove 7 and the like.
The slit 4 may be formed in the nozzle plate 5 in advance, or may be formed after the nozzle plate 5 is attached to the piezoelectric element block 2.

As described above, in this embodiment, since the slits 4 are formed in the nozzle plate 5 and the slits 4 are used instead of the conventional fine nozzle holes, the nozzle plate 5 is attached to the piezoelectric element block 2. At the time of installation, consideration should be given to nozzle clogging due to the adhesive and the nozzle plate 5
High-precision alignment between the pressure chamber and the pressure chamber groove 7 becomes unnecessary,
The work of attaching the nozzle plate 5 and the piezoelectric element block 2 is facilitated, and the productivity of the inkjet head 1 is improved. Also, by making the slits 4 formed as described above function in the same manner as the conventional nozzle holes, the trouble of forming a large number of minute nozzle holes at the same pitch with high accuracy is eliminated.
The number of production steps for the inkjet head 1 can be reduced.

The ink pool 6 attached to the upper rear end of the piezoelectric element block 2 communicates with each pressure chamber groove 7 via an ink introduction path (not shown).

In the ink jet head 1 having the above structure, when a positive voltage is applied to the electrode 9b on the pressure chamber groove 7 side and a negative voltage is applied to the electrodes 10a and 10b on the dummy groove 8 side. Piezoelectric element block 2 and top plate 3
The pressure wave is deformed as shown in FIG. 3 to reduce the volume of the pressure chamber groove 7 to generate a pressure wave inside the pressure chamber 15, and ink is ejected from the slit 4 of the nozzle plate 5 by the pressure wave.

At this time, the dummy grooves 8 on both sides of the pressure chamber 15 for discharging the ink are also deformed. However, since the ink is not introduced into the dummy grooves 8, there is no possibility of ejecting extra ink. The presence of the dummy groove 8 prevents the influence of the deformation of the pressure chamber 15 specified to discharge ink from affecting other pressure chambers 15. Therefore, in the present embodiment, the slit 4 formed in the nozzle plate 5 functions in the same manner as the conventional round nozzle having a small hole shape.

According to the present embodiment, the groove width of the dummy groove 8 can be made smaller than the groove width of the pressure chamber groove 7, so that the arrangement density of the pressure chambers 15 can be increased. Printing of a fine dot matrix or the like becomes possible, and the performance of printing or the like can be improved.

Further, according to the present embodiment, as described above, the arrangement density of the pressure chambers 15 can be increased as compared with the conventional example, so that the size of the ink jet head 1 can be reduced. (Printer) FIG. 4 shows the inkjet head 1 described above.
FIG. 2 is a diagram showing a schematic configuration of a printer 20 using the printer.

The printer 20 forms desired prints and images on the sheet 24 fed by the sheet feeding means 23 including a sheet feeding cassette 21 and a conveying roller 22 by the ink jet head 1 described above. ing.

The printer 2 according to the present embodiment as described above
No. 0 uses the inkjet head 1 which is easy to manufacture, has good productivity, and is inexpensive, so that the cost of the printer 20 itself can be reduced.

In the above description of the embodiment, the constituent materials, dimensions and manufacturing method of the ink jet head 1 are as follows.
This is merely an example for grasping the embodiment of the present invention qualitatively or quantitatively, and the present invention is not limited to this, and can be appropriately modified. In the above-described embodiment, the technique of forming the slits 4 in the nozzle plate 5 and making the slits 4 function as conventional nozzles is not limited to the inkjet head that discharges ink by deforming the piezoelectric element block 2. The present invention can also be applied to an ink jet head that discharges ink at the pressure of bubbles that have been swollen by heating.

[0033]

As described above, according to the present invention, a slit is formed in the nozzle plate so as to extend over each pressure chamber groove, and the slit functions as a conventional nozzle. The processing of the nozzle plate is facilitated, the work of fixing the nozzle plate to the piezoelectric body is facilitated, the productivity of the inkjet head can be improved, and a low-cost inkjet head can be provided.

Further, according to the present invention, since dummy grooves are formed on both sides of the pressure chamber groove to increase the arrangement density of the pressure chambers, the density of the dot matrix is increased, and the performance of printing and the like is improved. And the size of the ink jet head can be reduced.

Further, according to the present invention, the electrodes can be covered with an insulating film to prevent the generation of a precipitate caused by the electrolysis of the ink. Reliability can be improved.

Further, since the printer of the present invention uses an ink jet head which is inexpensive and has high reliability as described above, the cost of the printer itself can be reduced, and the reliability of the printer itself can be improved. Can be improved.

[Brief description of the drawings]

FIG. 1 is an external perspective view of an inkjet head according to an embodiment of the present invention.

FIG. 2 is a partially enlarged front view of the inkjet head (a partially enlarged view as viewed from the direction A in FIG. 1).

FIG. 3 is an operation state diagram of the inkjet head.

FIG. 4 is a schematic configuration diagram of a printer showing an embodiment of the present invention.

FIG. 5 is a sectional view of a main part of an ink jet head showing a first conventional example.

FIG. 6 is a sectional view of a main part of an ink jet head showing a second conventional example.

[Explanation of symbols]

 Reference Signs List 1 inkjet head 2 piezoelectric body (piezoelectric element block) 4 slit 5 nozzle plate 7 pressure chamber groove 8 dummy groove 9, 10 electrode 12 insulating film 13 control unit (CPU) 14 piezoelectric body operation control means 15 pressure chamber 20 printer 23 sheet Feeding means 24 sheets

Claims (6)

[Claims] 1. An ink jet head in which a plurality of pressure chambers into which ink has been introduced are arranged in parallel, and ink is ejected from nozzles of a nozzle plate fixed to one end of the pressure chamber. An inkjet head, characterized in that it is a slit extending over the pressure chamber. 2. An ink jet head in which a plurality of pressure chambers into which ink is introduced are arranged in parallel, and ink is ejected from nozzles of a nozzle plate fixed to one end of the pressure chamber, wherein a pressure chamber groove forming the pressure chamber is provided. A piezoelectric body having: a piezoelectric body operation control means for applying a voltage to the piezoelectric body to pressurize a specific pressure chamber; and a nozzle plate having a nozzle slit extending over the plurality of pressure chambers. An ink jet head characterized by the following. 3. An ink jet head in which a plurality of pressure chambers into which ink is introduced are arranged in parallel, and ink is ejected from nozzles of a nozzle plate fixed to one end of the pressure chamber, wherein a pressure chamber groove forming the pressure chamber is provided. A piezoelectric body having a dummy groove positioned on both sides of the pressure chamber groove; a piezoelectric body operation control unit for applying a voltage to the piezoelectric body to pressurize a specific pressure chamber; An ink jet head comprising: a nozzle plate having a slit for a nozzle; 4. An electrode disposed separately on the inner wall of the pressure chamber groove and the dummy groove of the piezoelectric body, an electrode on the pressure chamber groove side and an electrode on the dummy groove side. The inkjet head according to claim 3, further comprising: a control unit configured to apply voltages having different polarities to the control unit. 5. The ink jet head according to claim 4, wherein said electrode is covered with an insulating film. 6. The method according to claim 1, wherein
7. A printer comprising: the inkjet head described in item 1; and sheet feeding means for feeding a sheet to the inkjet head.