JPH11179920A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet head which can be reduced in size while eliminating machining of a piezoelectric actuator. SOLUTION: An ink jet head comprises a first ink chamber array 36 of a plurality of ink chambers 34 containing ink respectively, a second ink chamber array 42 of a plurality of ink chambers 40 arranged contiguously to the first ink chamber array 36 in parallel therewith while containing ink respectively, and a plurality of actuator parts corresponding to respective ink chambers 34, 40 of respective arrays 36, 42 for flying ink in the ink chamber by applying a pressure through deformation upon application of a voltage wherein these actuator parts comprises a plurality of active parts formed by subjecting a sheet of piezoelectric plate 50 partially to polarization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head for recording an image by adhering ink droplets flying according to image information to recording paper.

[0002]

2. Description of the Related Art Conventionally, in an ink jet type recording apparatus, there is known an ink jet head of a type in which ink in an ink chamber is pressurized by deformation of a piezoelectric member when a voltage is applied to cause ink droplets to fly from nozzles. Some ink jet heads of this type have a nozzle plate in which a large-diameter nozzle row and a small-diameter nozzle row are formed in parallel. In this case, usually, a plurality of independent ink chambers are respectively formed in communication with each other corresponding to the nozzles of each nozzle row, and a plurality of piezoelectric members are provided on the substrate corresponding to the respective ink chambers. ing. Each piezoelectric member is provided with an individual electrode and a common electrode for applying a voltage in accordance with image information, and the piezoelectric member is deformed when a driving voltage is applied between the electrodes.

[0003]

However, in the above-described ink jet head, when the piezoelectric members corresponding to the ink chambers of each nozzle row are formed, the piezoelectric members for the large-diameter nozzle row and the small-diameter nozzle row having different sizes are formed on the substrate. After the two piezoelectric plates were bonded and fixed, a separate groove was formed by dicer processing to separate and form each piezoelectric member.
It was necessary to prepare two types of piezoelectric plates, and processing was troublesome and time-consuming, resulting in poor productivity.

In addition, a common electrode of each piezoelectric member corresponding to the large-diameter nozzle row and a common electrode of each piezoelectric member corresponding to the small-diameter nozzle row need to be separately drawn out on the substrate.
This caused the head size to increase. further,
In the case where the piezoelectric member is a laminated piezoelectric member in which a plurality of piezoelectric layers are laminated, in order to prevent self-destruction (delamination) during driving, an inactive region which does not deform even when voltage is applied is formed. The head must be provided at both ends in the longitudinal direction of the piezoelectric member, and the size of the head is increased due to the presence of the inactive region.

[0005]

In order to solve the above-mentioned problems, an ink-jet head according to the present invention comprises a first row of ink chambers in which a plurality of ink chambers each containing ink are arranged, A second ink chamber row in which a plurality of ink chambers, each of which is provided adjacent to the first ink chamber row and which stores ink, are arranged in parallel with the direction in which the first ink chamber row is arranged; A plurality of actuators provided corresponding to the respective chambers and pressurizing and flying the ink in the ink chambers by the deformation at the time of voltage application, and these actuators partially polarize one piezoelectric flat plate. And a plurality of active portions formed as described above.

In this ink jet head, the piezoelectric flat plate may be a laminated piezoelectric flat plate in which a plurality of piezoelectric layers are stacked. In this case, between the respective piezoelectric layers of the piezoelectric flat plate, a plurality of individual electrodes respectively patterned corresponding to the respective actuator portions, and formed so as to extend to all the actuator portions and to be exposed on the side surfaces of the piezoelectric flat plate. A plurality of provided common electrodes may be arranged alternately. Also,
Between each piezoelectric layer of the piezoelectric flat plate, a plurality of individual electrodes pattern-formed corresponding to each actuator unit,
A plurality of common electrodes formed so as to extend in all the actuator portions are alternately arranged, and a groove for dividing each common electrode is formed in a portion of the piezoelectric plate where only the common electrode exists, and a conductive adhesive is formed in this groove. May be filled.

[0007]

According to the ink jet head of the present invention, 1
Since a plurality of active portions formed by partially polarizing a plurality of piezoelectric flat plates are actuator portions for pressurizing the respective ink chambers, a plurality of piezoelectric members are provided so as to individually correspond to the respective ink chambers. Need not be divided by dicer processing or the like, the manufacturing process can be simplified, and productivity can be improved. Also, since one piezoelectric flat plate can cover the actuator portions corresponding to the respective ink chambers of the first and second ink chamber rows, the size of the actuator section corresponding to each of the first and second ink chamber rows can be increased. It is not necessary to prepare two types of piezoelectric plates having different sizes, the type and cost of parts can be reduced, and the alignment of the two piezoelectric plates is not required at the time of assembling, which facilitates the assembling.

In the case of using a laminated piezoelectric flat plate formed by laminating a plurality of piezoelectric layers, only the actuator portion corresponding to each ink chamber is a polarized active portion, and all other regions are polarized. Since the non-active area is not a non-active area, the self-operation during driving can be performed without increasing the inactive area between the actuator section corresponding to the first ink chamber row and the actuator section corresponding to the second ink chamber row. Destruction can be prevented. Thus, the size of the head can be reduced as compared with the case where the divided piezoelectric members are provided for each row of ink chambers.

Further, between each piezoelectric layer of the laminated piezoelectric flat plate,
A plurality of individual electrodes, each of which is patterned in correspondence with each actuator, and a plurality of common electrodes, which are formed to extend to all the actuators and are provided so as to be exposed on the side surfaces of the piezoelectric flat plate, are alternately arranged. In this case, if an external electrode such as gold plating is provided on the side surface where the common electrode is exposed, it is possible to electrically connect the common electrode of all actuator units from the external electrode. This is necessary when the wiring for the common electrode is separately drawn out on the substrate from each piezoelectric member corresponding to the first ink chamber row and each piezoelectric member corresponding to the second ink chamber row. Space can be saved, which can also reduce the size of the head.

[0010] Further, between each piezoelectric layer of the laminated piezoelectric flat plate, a plurality of individual electrodes, each of which is patterned corresponding to each actuator section, and a plurality of common electrodes formed extending to all the actuator sections are alternately arranged. When a groove is formed in a portion of the piezoelectric plate where only the common electrode is present, and the groove is filled with a conductive adhesive, the presence of the groove causes the actuator portion on the first ink chamber row side to be formed. It is possible to suppress the interlocking displacement due to the mutual influence of the vibration between the actuator and the actuator section on the second ink chamber row side. In addition, the common electrode extending to all the actuators can be electrically connected from the conductive adhesive filled in the groove, so that the head can be downsized by saving space and the adhesive force of the adhesive can be used. Self-destruction of the piezoelectric flat plate in the groove can be prevented.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows four inkjet heads respectively corresponding to inks of yellow (Y), magenta (M), cyan (C), and black (K) along a paper passing direction (direction of arrow a) of the recording paper P. 1
This shows a state where 0, 12, 14, and 16 are arranged. These inkjet heads 10, 12, 14, 16 are line type heads each extending in a direction perpendicular to the paper passing direction and formed to have a length covering the entire width of the recording paper P. Since the configuration of each head is the same, the inkjet head 10 for yellow will be described below.

A nozzle plate 18 as shown in FIG. 2 is fixed to a portion of the ink jet head 10 facing the recording paper. The nozzle plate 18 has several large-diameter nozzles 2
Large-diameter nozzle rows 22 in which 0 (for example, an inner diameter of 32 μm) are arranged in a straight line are formed in a staggered manner along the longitudinal direction of the nozzle plate 18. The nozzle plate 18 has small-diameter nozzle rows 26 in which several small-diameter nozzles 24 (for example, an inner diameter of 23 μm) are arranged in a straight line. Each large-diameter nozzle row is located near both side edges along the longitudinal direction of the nozzle plate 18. 2
2 are formed in a staggered manner.

As shown in FIG. 3, an ink flow path plate 28 is adhered and fixed to the nozzle plate 18. A plurality of groove-shaped recesses covered by the nozzle plate 18 are formed in the ink flow path plate 28. Of these recesses, a groove-like recess extending in two directions starting from an ink supply port 30 into which ink flows from an ink cartridge (not shown) serves as an ink supply chamber 32. A plurality of narrow groove-shaped recesses formed inside the ink supply chamber 32 corresponding to the large-diameter nozzles 20 respectively form the large-diameter ink chambers 34.
It has become. Several large-diameter ink chambers 34 corresponding to the large-diameter nozzle row 22 are arranged in parallel with each other to form a large-diameter ink chamber row (first ink chamber row) 36. Each large-diameter ink chamber 34 communicates with the ink supply chamber 32 through a corresponding inlet groove 38, and is connected to the large-diameter nozzle 20 near the end of the large-diameter ink chamber 34 opposite to the inlet groove 38. Each is in communication.

Further, a plurality of narrow groove-shaped recesses formed outside the ink supply chamber 32 corresponding to the small diameter nozzles 24 are ink chambers 40 for small diameter. Small diameter nozzle row 2
The small-diameter ink chambers 40 corresponding to 6 are arranged in parallel with the arrangement direction of the large-diameter ink chamber rows 36 to form a small-diameter ink chamber row (second ink chamber row) 42. . The small-diameter ink chamber row 42 is provided adjacent to the large-diameter ink chamber row 36 with the ink supply chamber 32 interposed therebetween. The length of the small diameter ink chamber 40 is shorter than the length of the large diameter ink chamber 34. Each small-diameter ink chamber 40 communicates with the ink supply chamber 32 via a corresponding inlet groove 38, and is connected to the small-diameter nozzle 24 near the end of the small-diameter ink chamber 40 opposite to the inlet groove 38. Each is in communication.

A plurality of single piezoelectric flat plates 50 are adhered to the back surface of the ink flow path plate 28 so as to correspond to a pair of large-diameter and small-diameter ink chamber rows 36 and 42, respectively. Each piezoelectric flat plate 50 is bonded and fixed on a ceramic substrate 54 held by a holder 52. FIG. 4 shows a state where the piezoelectric flat plate 50 is arranged on the substrate 54. A groove 56 extending in the longitudinal direction of the substrate 54 is formed at the center of the substrate 54, and each piezoelectric flat plate 50
6 are arranged in a zigzag on both sides.

The piezoelectric flat plate 50 is a laminated piezoelectric flat plate formed by laminating a plurality of piezoelectric layers, and is manufactured as shown in FIG. First, a piezoelectric material (for example, P
ZT) on the surface of the green sheet 60, the individual electrodes 58a,
A pattern 58b is formed in advance by sputtering, plating, or the like, corresponding to each of the ink chambers 34 and 40. The individual electrodes 58a corresponding to the large-diameter ink chamber 34 are formed in strips extending from one edge of the green sheet 60, and the individual electrodes 58b corresponding to the small-diameter ink chamber 40 are formed.
Are formed in strips extending from the other edge of the green sheet 60, respectively. The individual electrode 58a is formed longer than the individual electrode 58b corresponding to the difference in the length of each of the ink chambers 34 and 40. At a substantially central portion of the green sheet 60, a region 62 where no electrode is formed is left.

Next, a second-layer green sheet 6 made of the same piezoelectric material is placed on the first-layer green sheet 60.
4 is laminated. On the upper surface of the green sheet 64, the common electrode 6 is formed on almost the entire surface of the green sheet 64, except for the strip portions 65 near both ends.
6 is formed in advance by sputtering or plating. Thereafter, the same green sheet as the first layer is laminated as a third layer on the second layer green sheet 64, and the same green sheet as the second layer is laminated as a fourth layer thereon. After repeating the process and laminating a predetermined number of green sheets (for example, 20 layers), a green sheet 68 on which no electrode is formed is finally laminated, and the green sheets of each layer are brought into close contact with each other by pressing from above.

Thereafter, as shown in FIG. 6, external electrodes 70 for conducting the individual electrodes 58b of each layer are formed by, for example, gold plating. Similarly, an external electrode (not shown) is formed for the other individual electrode 58a. Further, external electrodes 72 (only one is shown) for conducting the common electrode 66 of each layer provided to be exposed on both side surfaces orthogonal to the side surface on which the external electrode 70 is formed are formed on both side surfaces by, for example, gold plating. I do. Then, by firing this laminate, a piezoelectric flat plate 50 is completed.

Subsequently, the individual electrodes 58a, 58b
And a common electrode 66 is applied with a high voltage to partially polarize the piezoelectric flat plate 50. Thereby, as shown in FIG.
Areas of the piezoelectric flat plate 50 where the individual electrodes 58a and 58b and the common electrode 66 overlap each other become active portions, and the individual electrodes 58a and 58 via the external electrodes 70 and 72, respectively.
Actuators 74 and 76 that are deformed when a drive voltage is applied between b and common electrode 66. On the other hand, between the actuator parts 74 and 76 is a non-polarized inactive part 78 in which only the common electrode 66 exists.

As described above, a plurality of individual electrodes 58a and 58b each having a pattern formed corresponding to each of the actuators 74 and 76 are provided between the piezoelectric layers formed by firing the stacked green sheets. Of the piezoelectric flat plate 50
Common electrodes 66 provided to be exposed on the side surfaces of
And are alternately arranged. Further, in the piezoelectric flat plate 50, each actuator section 74 is provided with the large-diameter ink chamber row 36.
The actuator sections 76 are provided corresponding to the respective ink chambers 40 of the small-diameter ink chamber row 42. The length of the actuator 74 is longer than that of the actuator 76 in accordance with the difference in the length of the individual electrodes 58a and 58b.

As shown in FIG. 4, on the substrate 54, lead wires 73 electrically connected to the external electrodes 72 of the respective piezoelectric flat plates 50 are formed in a pattern.
The common electrode 66 of each of the piezoelectric flat plates 50 is connected to the ground via the third. On the other hand, on the side surface of the substrate 54, there are formed lead-out lines 71 which are respectively connected to the external electrodes 70 formed on the side surfaces of the respective piezoelectric flat plates 50. Fifty individual electrodes 58a and 58b are connected to a drive voltage application driver (not shown), respectively.

In the ink jet head 10 having the above-described structure, the ink supplied from the ink cartridge (not shown) to the ink supply chamber 32 is supplied to the corresponding inlet groove 3.
8 are accommodated in the large-diameter and small-diameter ink chambers 34 and 40, respectively. In this state, the individual electrodes 58a and 58b of the piezoelectric flat plate 50 are supplied from the driver according to the image information.
When a drive voltage is applied between the actuator and the common electrode 66, the actuators 74 and 76 are instantaneously deformed in the thickness direction and pressurize the ink in the corresponding ink chambers 34 and 40. Ink droplets having different sizes fly from the small-diameter nozzle 24. These ink droplets adhere to the recording paper to form dots of different sizes, and an image is recorded by a set of these dots.

As described above, in the ink-jet head 10 of the present embodiment, a plurality of active portions formed by partially polarizing one piezoelectric flat plate 50 are formed in each of the ink chambers 3.
Actuator parts 74 and 7 for pressing the pressures 4 and 40, respectively
Since it is 6, it is not necessary to separately form the piezoelectric member by dicer processing or the like so as to correspond to each of the ink chambers 34 and 40, and the manufacturing process can be simplified and the productivity is improved. In addition, one piezoelectric flat plate 50 can cover the actuator sections 74 and 76 corresponding to the ink chambers 34 and 40 of the large-diameter and small-diameter ink chamber rows 36 and 42, respectively. It is not necessary to prepare two types of piezoelectric plates having different sizes for the row of ink chambers for small diameters, which can reduce the types and costs of parts, and eliminate the need to align the two piezoelectric plates during assembly, thus assembling. Becomes easier. Note that these effects can be obtained even when the piezoelectric flat plate 50 is not of a laminated type but of a single layer.

Further, in the laminated piezoelectric flat plate 50 in which a plurality of piezoelectric layers are laminated, only the actuator portions 74 and 76 corresponding to the ink chambers 34 and 40 are polarized active portions. Since all the regions are inactive regions that are not polarized, the inactive portion 78 between the actuator portion 74 corresponding to the large-diameter ink chamber row 36 and the actuator section 76 corresponding to the small-diameter ink chamber row 42 is not so much. Self-destruction (delamination) during driving can be prevented without taking a large value. Thereby, each of the ink chamber rows 36, 4
The size of the head can be reduced as compared with the case where the piezoelectric members divided for the two ink chambers 34 and 40 are provided.

Further, a plurality of individual electrodes 58a and 58b each having a pattern corresponding to each of the actuator portions 74 and 76 are provided between the respective piezoelectric layers of the laminated piezoelectric flat plate 50.
Since the plurality of common electrodes 66 formed so as to extend to all the actuator portions 74 and 76 and provided so as to be exposed on the side surfaces of the piezoelectric flat plate 50 are alternately arranged, the side surfaces on which the common electrodes 66 are exposed are provided. By providing an external electrode 72 made of, for example, gold plating, the external electrode 72 can be electrically connected to the common electrode 66 of all the actuator units 74 and 76. This is necessary when the wiring for the common electrode is separately drawn out from the piezoelectric members corresponding to the large-diameter ink chamber row 36 and the piezoelectric members corresponding to the small-diameter ink chamber row 42 on the substrate. Space can be saved, which can also reduce the size of the head.

By the way, the ink jet head 10
Then, the piezoelectric flat plate 8 shown in FIG.
0 may be used. In the piezoelectric flat plate 80, a groove 82 for dividing each common electrode 66 is formed in a non-active portion where only the common electrode 66 is present in the piezoelectric flat plate 50 by a dicer process or the like. 84. When this piezoelectric flat plate 80 is used,
Due to the presence of the groove 82, it is possible to suppress the interlocking displacement caused by the mutual influence between the actuator section 74 on the large-diameter ink chamber row 36 side and the actuator section 76 on the small-diameter ink chamber row 42 side. . In addition, the electrical connection of the common electrode 66 extending from the conductive adhesive 84 filled in the groove 82 to all the actuator portions 74 and 76 can be made, and the space can be saved as in the case of the piezoelectric plate 50 described above. The head can be miniaturized and the adhesive 8
The self-destruction (delamination) of the piezoelectric flat plate 80 in the groove 82 can be prevented by the adhesive force of No. 4. In the piezoelectric flat plate 80, since the electrical connection of each common electrode 66 can be made from the conductive adhesive 84, the piezoelectric flat plate 50 can be electrically connected.
It is not necessary to provide the external electrode 72 by gold plating or the like on the side surface.

In the above described ink jet head 10, the diameters of the nozzles 20, 24, the ink chambers 34, 40
And large and small ink droplets are ejected by making the lengths of the actuator portions 74 and 76 different.
The present invention can be applied to a case where the nozzle diameter, the ink chamber length, and the actuator section length are the same.

Although the ink jet head 10 has been described as a line type head, the present invention can also be applied to an ink jet head mounted on a carriage and scanning a recording sheet.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which four line-type inkjet heads are arranged along a recording paper passing direction.

FIG. 2 is a plan view showing a nozzle surface of the line type inkjet head.

FIG. 3 is a partially cutaway perspective view showing the internal configuration of the ink jet head.

FIG. 4 is a partial perspective view showing a state where a plurality of piezoelectric flat plates are arranged on a substrate.

FIG. 5 is a perspective view for explaining a laminated state of the piezoelectric flat plates.

FIG. 6 is a perspective view of a piezoelectric flat plate.

FIG. 7 is a cross-sectional view of the piezoelectric flat plate of FIG. 6, taken along line VII-VII.

FIG. 8 is a perspective view showing another form of a piezoelectric flat plate.

[Explanation of symbols]

10: inkjet head, 34: large-diameter ink chamber,
36 ... large-diameter ink chamber row (first ink chamber row), 40 ...
Small-diameter ink chamber, 42: Small-diameter ink chamber row (second ink chamber row), 50: Piezoelectric flat plate, 74, 76: Actuator section.

Claims (3)

[Claims] 1. A first ink chamber row in which a plurality of ink chambers respectively storing ink are arranged, and a plurality of ink chambers provided adjacent to the first ink chamber row and each storing ink. Are provided corresponding to the second ink chamber row arranged in parallel with the arrangement direction of the first ink chamber row, and the ink chambers of each row, and the inside of the ink chamber is deformed by voltage application. An ink jet head comprising a plurality of actuators for pressurizing and flying ink, the actuators comprising a plurality of active portions formed by partially polarizing one piezoelectric flat plate; 2. The ink jet head according to claim 1, wherein the piezoelectric flat plate is a laminated piezoelectric flat plate formed by stacking a plurality of piezoelectric layers. 3. A plurality of individual electrodes which are respectively formed in a pattern corresponding to each actuator portion between each piezoelectric layer of the piezoelectric flat plate, and are formed so as to extend to all the actuator portions and are exposed on side surfaces of the piezoelectric flat plate. 3. The ink jet head according to claim 2, wherein a plurality of common electrodes provided so as to be alternately arranged.