DE60306824T2 - Inkjet head and inkjet printer - Google Patents

Description

GENERAL STATUS OF THE TECHNOLOGY

1st area the invention

The The present invention relates to an ink jet head for printing by ejecting ink onto a print medium and an inkjet printer, having the ink jet head.

2. Description of the state of the technique

In An ink jet head distributes ink to an ink jet printer supplied from an ink tank becomes, to pressure chambers. The ink jet head selectively applies pressure to each pressure chamber to eject ink through a nozzle. As a means for selectively applying pressure to the pressure chambers, an actuator unit be used, are laminated in the ceramic piezoelectric layers.

Around to give an example, an ink jet head of this kind is known, the one single actuator having, in the continuous flat piezoelectric layers, which are over several pressure chambers extend, are laminated and at least one the piezoelectric layers between a common electrode, which is shared by many pressure chambers and at the grounding potential is held, and many individual electrodes, d. H. Drive electrodes, at positions corresponding to the respective pressure chambers, are enclosed (see US Pat. No. 5,402,159). The part of the piezoelectric layer between the individual Electrodes and the common electrode is enclosed and is polarized in its thickness, is in its thickness direction as an active layer by the so-called piezoelectric longitudinal effect expands or contracts when attached to a single electrode on one Side of the situation another potential is created than to the common Electrode on the other side. This changes the volume of the corresponding pressure chamber, allowing ink through a nozzle, the with the pressure chamber in fluid communication is, is ejected in the direction of a pressure medium.

Around good ink ejection results with such an ink jet head To reach, the operating unit must precise be positioned at a passage unit such that the individual electrodes are in predetermined positions have to, which correspond to the respective pressure chambers in a plan view.

In many cases becomes such an ink jet head as described above due to various manufacturing limitations in the following way produced. This means, the passage unit, in which ink passages containing pressure chambers, are formed, is made separately from the actuator unit. The passage unit is then bonded to the actuator unit with an adhesive glued that the pressure chambers close to the actuator unit are located. This gluing process marks the passage unit with a mark on the actuator in accordance brought.

in the Generally, however, the piezoelectric layers become the actuator unit produced by a sintering process, while the passage unit is laminated with metal foils. That's why the position accuracy The Elek electrodes the smaller, the larger the piezoelectric layers are. The longer the head is, the harder the positioning process becomes between the pressure chambers in the passage unit and the individual Electrodes in the operating unit. As a result, the production yield of the heads may be reduced.

on the other hand is the operating unit an expensive tiny component, and because it's made of ceramic, she is very brittle. Especially with the operating unit, which has a polygonal shape, easily break off the corners. Breakage loss is a cause of an increase in manufacturing costs. Furthermore, the actuator unit be handled very carefully, so that no corner against another Component abuts. Thereby the mounting of the ink jet head becomes difficult.

Out EP 0 620 670 For example, an image display device is known that compensates for inaccurate component alignment and seam artifacts by providing a deliberate transversal overlap between adjacent regions.

SUMMARY THE INVENTION

A The object of the present invention is to provide an ink jet head, in which an operating unit precise is positioned relative to a passage unit.

A Another object of the present invention is the provision an ink jet head in which an operating unit is difficult to break can be.

According to the present An ink jet head according to claim 1 is provided.

With this construction, each of the operating units can be arranged independently of the others relative to the passage unit. Therefore even in the case of a long head, the increase of the positional shift between the electrode and the pressure chamber of each actuator unit can be avoided. Thus, both can be precisely positioned relative to each other. As a result, good ink ejection results can be achieved, and the production yield of the heads is increased. In addition, because the pressure generating sections in the additional area located in one operating unit correspond to the gap portion between them and the pressure generating sections in the base area of an adjacent operating unit, the number of pressure generating sections in the immediate vicinity of the seam section between the operating unit and the adjacent operating unit can not be brought to a small value. Therefore, a head can be manufactured in which there is substantially no fluctuation in the number of pressure generating sections in the longitudinal direction of the passage unit.

SHORT DESCRIPTION THE DRAWINGS

Other and other objects, features and advantages of the invention go from the following description taken in conjunction with the accompanying drawings which shows:

1 Fig. 10 is a general view of an ink-jet printer incorporating ink-jet heads according to a first embodiment of the present invention.

2 Fig. 15 is a perspective view of an ink jet head according to a first embodiment of the present invention.

3 is a sectional view taken along the line III-III in 2 ,

4 FIG. 10 is a plan view of a head main body incorporated in the ink jet head of FIG 2 is included.

5 is an enlarged view of the area enclosed by a dot-dash line in FIG 4 ,

6 is an enlarged view of the area enclosed by a dot-dash line in FIG 5 ,

7 is a partial sectional view of the head main body of 4 ,

8th FIG. 14 is an enlarged view of the area bounded by a one-dash two-dot line in FIG 5 ,

9 is a partially exploded view of the head main body of 4 ,

10 FIG. 14 is an enlarged sectional view of a side view of the area in FIG 7 is delimited with a dot-dash line.

11 Fig. 10 is a plan view of a head main body included in an ink jet head according to a second embodiment of the present invention.

12 is a view from below of the head main body of 11 ,

13 FIG. 16 is a cross-sectional view of the head main body of FIG 11 ,

14 is an enlarged view of the area Q in FIG 13 is delimited with a dot-dash line.

15 is a partial sectional view of the head main body of 11 ,

16 FIG. 10 is an enlarged sectional view showing the detailed structure of an actuator unit in the head main body of FIG 11 illustrated.

17 FIG. 10 is an enlarged plan view of an operating unit in the head main body of FIG 11 ,

18 is an enlarged plan view showing a seam portion between two actuation units of 17 shows.

19 FIG. 10 is an enlarged plan view of an actuator unit according to a modification of a second embodiment of the present invention. FIG.

20 is an enlarged plan view showing a seam portion between two actuation units of 19 shows.

21A Fig. 11 is a plan view of a head main body included in an ink jet head according to a modification of the second embodiment in which four actuator units are arranged.

21B Fig. 10 is a plan view of a head main body included in an ink jet head according to another modification of the second embodiment in which four actuator units are arranged.

22 FIG. 10 is a plan view of a head main body used in an ink jet head according to a third embodiment of the present invention. FIG is included.

23 is a view from below of the head main body of 22 ,

24 FIG. 16 is a cross-sectional view of the head main body of FIG 22 ,

25 is an enlarged view of the area E in 24 is delimited with a dot-dash line.

26 is a partial sectional view of the head main body of 22 ,

27 FIG. 10 is an enlarged sectional view showing the detailed structure of an actuator unit in the head main body of FIG 22 illustrated.

28A FIG. 12 is a schematic view illustrating the profile of an operating unit included in the head main body of FIG 22 is included.

28B Fig. 12 is a schematic view illustrating the profile of an actuator unit as a modification.

29A FIG. 12 is a plan view of a modification of the head main body of FIG 22 containing heptagonal actuators.

29B FIG. 10 is a plan view of an operating unit included in the head main body of FIG 29A is included.

30A FIG. 10 is a plan view of another modification of the head main body of FIG 22 containing octagonal actuators.

30B FIG. 10 is a plan view of an operating unit included in the head main body of FIG 30A is included.

31A FIG. 10 is a plan view of another modification of the head main body of FIG 22 containing partially rounded actuators.

31B FIG. 10 is a plan view of an operating unit included in the head main body of FIG 31A is included.

32 Fig. 12 is a schematic view of a principal part of an ink jet printer according to the fourth embodiment of the present invention.

DESCRIPTION THE PREFERRED EMBODIMENTS

First, for understanding ink jet heads according to embodiments of the present invention, an ink jet head will be described with reference to FIGS 1 to 10 described. 1 Fig. 10 is a general view of an ink-jet printer incorporating ink-jet heads according to a first embodiment of the present invention. The in 1 illustrated inkjet printers 101 is a color inkjet printer with four inkjet heads 1 , In this printer 101 are a paper feed unit 111 and a paper output unit 112 in a left or a right section of 1 arranged.

In the printer 101 A paper transport path extends from the paper feed unit 111 to the paper output unit 112 , A pair of feed rollers 105a and 105b is the paper feed unit 111 immediately downstream to grab and forward a paper as an image recording medium. By means of the pair of feed rollers 105a and 105b the paper is going from left to right in 1 transported. In the middle of the paper transport path are two belt circulating rollers 106 and 107 and an endless conveyor belt 108 arranged. The conveyor belt 108 runs around the belt rollers 106 and 107 around and extends between them. The outside, ie the transport side, of the conveyor belt 108 is treated with silicone. Thus, a paper passing through the pair of feed rollers 105a and 105b is passed through, on the transport side of the conveyor belt 108 be held by means of the adhesion of the silicone-treated side. In this condition, the paper is transported downstream (to the right) by a belt roller 106 in the clockwise direction in 1 is driven (the direction indicated by an arrow 104 is designated).

pressure elements 109a and 109b are at positions for feeding a paper to the band roller 107 or for taking down the paper from the strip roller 106 arranged. Each of the pressure elements 109a and 109b serves to press the paper onto the transport side of the conveyor belt 108 so that the paper does not get off the transport side of the conveyor belt 108 can solve. Thus, the paper adheres securely to the transport side.

A detachment device 110 is along the paper transport path the conveyor belt 108 immediately downstream. The detachment device 110 releases the paper that is on the transport side of the conveyor belt 108 adheres, from the transport side, to the paper toward the right side paper output unit 112 to transport.

Each of the four inkjet heads 1 has a head main body at its lower end 1a , Each head main body 1a has a rectangular cross-section. The head main body 1a are arranged close to each other, with the longitudinal axis of each head main body 1a perpendicular to the paper transport direction (perpendicular to the 1 ) runs. That is, this printer 101 is a line printer. The bottom of each of the four head main bodies 1a is facing the paper transport path. In the bottom of each head main body 1a There are a number of nozzles each having an ink ejection opening with a small diameter. The four head main bodies 1a Inject ink of the colors magenta, yellow, cyan or black.

The head main body 1a are arranged so that a narrow clearance between the bottom of each head main body 1a and the transport side of the conveyor belt 108 arises. The paper transport path runs within the free space. In this construction will be - while a paper passing through the conveyor belt 108 is transported, immediately under the four head main bodies 1a is passed in sequence - the respective color inks are ejected through the respective nozzles toward the top, ie the printing side, of the paper to produce a desired color image on the paper.

The inkjet printer 101 is with a maintenance unit 117 for automatic maintenance of inkjet heads 1 fitted. The maintenance unit 117 contains four caps 116 for covering the bottoms of the four head main bodies 1a and a non-illustrated cleaning system.

While the inkjet printer 101 prints, is the maintenance unit 117 in a position immediately under the paper feed unit 117 (Retreat position). When, after the completion of the printing operation, a predetermined condition is filled (for example, when a state in which no printing is carried out continues for a predetermined period or when the printer 101 is turned off), the maintenance unit moves 117 in a position immediately under the four head main bodies 1a (Cap position), in which the maintenance unit 117 the bottoms of the head main body 1a with the respective caps 116 covered to prevent ink in the nozzles of the head main body 1a dries.

The belt rollers 106 and 107 and the conveyor belt 108 be from a support frame 113 carried. The supporting frame 113 is located on a cylindrical element 115 under the support frame 113 is arranged. The cylindrical element 115 can be about a wave 114 rotate, which is disposed at a position from the center of the cylindrical member 115 differs. Thus, by turning the shaft 114 the height of the topmost portion of the cylindrical element 115 be changed to the support frame 113 move up or down accordingly. When the maintenance unit 117 moved from the retreat position to the cap position, so must the cylindrical element 115 previously rotated by a predetermined angle to the conveyor belt 108 and the belt rollers 106 and 107 to get a necessary distance from the in 1 illustrated position to move down. This will make room for the movement of the maintenance unit 117 guaranteed.

In the of the conveyor belt 108 surrounded area is a nearly rectangular Parallelflachförmige guide 121 (whose width is substantially equal to the width of the conveyor belt 108 corresponds) at a position corresponding to the inkjet heads 1 opposite. The leadership 121 is in contact with the underside of the upper part of the conveyor belt 108 to the upper part of the conveyor belt 108 to support from the inside.

Next, the structure of each ink jet head will be explained 1 described in more detail according to this embodiment. 2 Fig. 16 is a perspective view of the ink jet head 1 , 3 is a sectional view taken along the line III-III in 2 , Let us turn to that 2 and 3 to. The inkjet head 1 according to this embodiment, includes a head main body 1a which has a rectangular shape as seen from above and extends in one direction (the main scanning direction) and a base portion 131 for supporting the head main body 1a , The base section 131 containing the head main body 1a carries, further carries drive ICs 132 for supplying drive signals to individual electrodes 35a and 35b (please refer 6 and 10 ) as well as substrates 133 ,

Let us turn 2 to. The base section 131 consists of a basic block 138 partially to the top of the head main body 1a is bonded to the head main body 1a to wear, and a holder 139 which is at the top of the base block 138 Bonded to the base block 138 to wear. The basic block 138 is a nearly rectangular parallelepiped member of substantially the same length as the head main body 1a , The basic block 138 Made of a metallic material such as stainless steel serves as a lightweight structure for reinforcing the holder 139 , The holder 139 consists of a holder main body 141 standing near the head main body 1a is arranged, and a pair of holding power sections 142 each of which is on the side of the holder main body 141 extending to the head main body 1a opposite. Each holding section 142 is configured as a flat element. These holding yield sections 142 extend in the longitudinal direction of the holder main body 141 and are arranged parallel to each other at a predetermined distance.

Paired, downhill casing sections 141 are in both end portions of the holder main body 141 in a sub-scanning direction (perpendicular to the main scanning direction). Each surround section 141 extends over the entire length of the holder main body 141 , As a result, in the lower portion of the holder main body 141 through the pair of skirt sections 141 a nearly rectangular parallelepiped-shaped channel 141b educated. The basic block 138 is in the gutter 141b added. The top of the base block 138 is at the bottom of the gutter 141b the holder main body 141 glued with an adhesive. The basic block 138 is a little thicker than the gutter 141b the holder main body 141 is deep. As a result, the lower end of the base block protrudes 138 down over the skirt sections 141 out.

Inside the basic block 138 is - as a passage for ink, the head main body 1a is to be supplied - an ink reservoir 3 as a nearly rectangular cuboidal space (cavity) formed in the longitudinal direction of the base block 138 extends. In the bottom 145 of the basic block 138 are openings 3b (please refer 4 ) formed respectively with the ink reservoir 3 be in fluid communication. The ink reservoir 3 is connected via an unillustrated feed tube to an unexposed main ink tank (ink supply source) within the printer main body. Thus, the ink reservoir becomes 3 expediently supplied ink from the main ink tank.

On the bottom 145 of the basic block 138 juts out the immediate surroundings of each opening 3b from the surrounding section down. The basic block 138 stands with a passage unit 4 (please refer 3 ) of the head main body 1a at the only immediate surrounding section 145a every opening 3b the bottom 145 in contact. Thus, the area is the bottom 145 of the basic block 138 except for the immediate environment section 145a every opening 3b from the head main body 1a spaced. actuating units 21 are arranged at a distance.

On the outer side surface of each holder section 142 of the owner 139 is a drive IC 132 with an elastic element 137 , such as a sponge therebetween. A heat sink 134 is in close contact with the outer side surface of the driving IC 132 arranged. The heat sink 134 consists of a nearly rectangular cuboidal element for efficiently radiating heat contained in the driving IC 132 arises. A flexible printed circuit (FGS) 136 acting as a power supply element is connected to the drive IC 132 connected. The with the driving IC 132 affiliated FGS 136 is to the corresponding substrate 133 and the head main body 1a soldered and electrically connected to them. The substrate 133 is outside the FGS 136 over the driving IC 132 and the heat sink 134 arranged. The top of the heat sink 134 is with a sealing element 149 to the substrate 133 bonded. In addition, the bottom of the heat sink 134 with a sealing element 149 to the FGS 136 bonded.

Between the bottom of each facing section 141 the holder main body 141 and the top of the passage unit 4 is a sealing element 150 arranged so that the FGS 136 between. The FGS 136 is through the sealing element 150 at the passage unit 4 and the holder main body 141 attached. Therefore, even with an elongated head main body 1a prevents the head main body 1a is bent; It can be prevented that the connecting portion between each actuator unit and the FGS 136 mechanical stress is exposed, and the FGS 136 can be kept safe.

Let us turn 2 to. In the immediate vicinity of each lower corner of the inkjet head 1 along the main scanning direction are six protruding portions 30a at regular intervals along the corresponding side wall of the ink jet head 1 arranged. These protruding sections 30a are located at both ends in the sub-scanning direction of a nozzle plate 30 in the lowermost layer of the head main body 1a (please refer 7A and 7B ). The nozzle plate 30 is along the boundary line between each protruding section 30a and the other section bent about 90 degrees. The protruding sections 30a are located at positions corresponding to the immediate surroundings of the two ends of different sheets of paper to be printed. Each bent section of the nozzle plate 30 has a shape that is not right-angled, but rounded. This configuration makes it difficult for a piece of paper to hang, ie to jam, which can happen because the leading edge of the paper is attached to the head 1 was transported against the side surface of the head 1 encounters.

4 FIG. 12 is a schematic plan view of the head main body. FIG 1a , In 4 is an ink reservoir 3 that in the basic block 138 is formed, phantomly illustrated with a broken line. Let us turn 4 to. The head main body 1a has a rectangular shape as seen from above, which extends in one direction (the main scanning direction). The head main body 1a contains a passage unit 4 in which a large number of pressure chambers 10 and a large number of ink ejection 8th at the front ends of the nozzles (for both see 5 . 6 and 7 ) are formed, as will be described below. Trapezoidal actuators 21 , which are arranged zigzag in two rows, are on top of the passage unit 4 bonded. Each actuation unit 21 is arranged so that its parallel opposite sides (top and bottom) in the longitudinal direction of the passage unit 4 run. The oblique sides of all adjacent actuators 21 overlap in the lateral direction of the passage unit 4 ,

The bottom of the passage unit 4 that is the bonded area of each actuator unit 4 is made an ink ejection area. In the surface of each ink ejection area are a large number of ink ejection openings 8th arranged in a matrix, as will be described below. In the basic block 138 that is above the passage unit 4 is disposed, is an ink reservoir 3 in the longitudinal direction of the base block 138 educated. The ink reservoir 3 stands with an (unexposed) ink tank over an opening 3a placed in one end of the ink reservoir 3 is formed, so in fluid communication that the ink reservoir 3 always filled with ink. In the ink reservoir 3 are pairs of openings 3b in areas where there is no operating unit 21 are arranged so that they zigzag in the longitudinal direction of the ink reservoir 3 run.

5 is an enlarged view of the area enclosed by a dot-dash line in FIG 4 , Let us turn to that 4 and 5 to. The ink reservoir 3 stands over every opening 3b with a distribution channel 5 under the opening 3b is arranged, in fluid communication. Every opening 3b is provided with a filter (not shown) to catch dust and dirt contained in the ink. The front end portion of each distribution channel 5 branches into two sub-distribution channels 5a , Under a single operating unit 21 two sub-distribution channels extend 5a from each of the two openings 3b on both sides of the operating unit 21 in the longitudinal direction of the ink jet head 1 , That is, under the single operating unit 21 a total of four sub-distribution channels extend 5a in the longitudinal direction of the ink jet head 1 , Each sub-distribution channel 5a is filled with ink coming from the ink reservoir 3 is introduced.

6 is an enlarged view of the area enclosed by a dot-dash line in FIG 5 , Let us turn to that 5 and 6 to. On top of each actuator unit 21 are individual electrodes 35a , each of which - viewed from above - have a nearly rhombic shape, regularly arranged in a matrix. There are also individual electrodes 35b with the same shape as the individual electrodes 35a in the operating unit 21 arranged so that they have the respective individual electrodes 35a overlap. A large number of ink ejection openings 8th are regularly in a matrix in the surface of the ink ejection area corresponding to the actuator unit 21 the passage unit 4 arranged. In the passage unit 4 are pressure chambers (cavities) 10 , which - viewed from above - each have a nearly rhombic shape, which is slightly larger than that of the individual electrodes 35a and 35b , arranged regularly in a matrix. In addition, in the passage unit 4 also still openings 12 regularly arranged in a matrix. These pressure chambers 10 and openings 12 stand with the appropriate ink ejection openings 8th in fluid communication. The pressure chambers 10 are arranged at positions corresponding to the respective individual electrodes 35a and 35b corresponding. Viewed from above, is the big part of each electrode 35a and 35b in an area of the corresponding pressure chamber 10 contain. In the 5 and 6 are - for better understanding of the drawings - the pressure chambers 10 , the openings 12 etc. with solid lines, although they should be illustrated with broken lines because they are within the actuator unit 21 or the passage unit 4 are located.

7 Fig. 16 is a partial sectional view of the head main body 1a from 4 in the longitudinal direction of a pressure chamber. How out 7 it can be seen, is any ink ejection opening 8th formed at the front end of a tapered nozzle. Each ink ejection opening 8th is above a pressure chamber 10 (Length: 900 μm, width: 350 μm) and an opening 12 with a sub-distribution channel 5a in fluid communication. Thus, within the inkjet head 1 Ink passages 32 each formed by an ink tank via an ink reservoir 3 , a distribution channel 5 , a sub-distribution channel 5a , an opening 12 and a pressure chamber 10 to an ink ejection port 8th extend.

Let us turn 7 to. The pressure chamber 10 and the opening 12 are arranged at different levels. Therefore, in the section of the passage unit 4 the ink ejection area under an actuator unit 21 corresponds to an opening 12 that with a single pressure chamber 10 is in fluid communication, within the same portion - seen from above - be arranged like a pressure chamber 10 , which is next to the pressure chamber 10 located with the opening 12 is in fluid communication. As a result - because the pressure chambers 10 arranged with a high density close to each other can be - a high resolution image printing by means of an ink jet head 1 be realized with a relatively small occupancy area.

In the plane of 5 and 6 are pressure chambers 10 disposed in an ink ejection region in two directions, one direction in the longitudinal direction of the ink jet head 1 (first arrangement direction) and a direction slightly oblique to the lateral direction of the ink jet head 1 runs (second arrangement direction). The first and second arrangement directions form an angle θ which is a little smaller than the right angle. The ink ejection openings 8th are arranged in the first arrangement direction at 50 dpi (dots per inch). The pressure chambers 10 on the other hand, in the second arrangement direction, the ink ejection area of a single operation unit is arranged 21 corresponds to twelve pressure chambers 10 contains. That's why it's within the full width of the inkjet head 1 in an area of the space between two ink ejection openings 8th which are juxtaposed in the first arrangement direction, twelve ink ejection openings 8th , At both ends of each ink ejection area in the first arrangement direction (corresponding to an oblique side of the actuator unit 21 ), the above condition is satisfied by making a compensation relation to the ink ejecting area, which is the opposite operating unit 21 in the lateral direction of the ink jet head 1 equivalent. That's why you can in the inkjet head 1 by ejecting ink droplets in sequence through a large number of ink ejection orifices 8th which are in the first and the second direction angeord net, upon relative movement of a paper in the lateral direction of the ink jet head 1 print at 600 dpi in the main scanning direction.

Next, the structure of the passage unit 4 in detail by means of 8th described. 8th Fig. 12 is a schematic view showing the positional relationship between each pressure chamber 10 , every ink ejection opening 8th and every opening (every restricted passage) 12 shows. Let us turn 8th to. pressure chambers 10 are arranged in rows in the first arrangement direction at predetermined intervals of 500 dpi. Twelve rows of pressure chambers 10 are arranged in the second arrangement direction. Overall, the pressure chambers 10 in the ink ejection area, that of a single actuator unit 21 corresponds, arranged two-dimensionally.

The pressure chambers 10 are classified into two types, namely pressure chambers 10a , in each case a nozzle with the upper acute-angled section in 8th connected, and pressure chambers 10b , in each of which a nozzle is connected to the lower acute-angled portion. The pressure chambers 10a and 10b are in the first arrangement direction to pressure chamber rows 11a respectively. 11b arranged. Let us turn 8th to. In the ink ejection area, that of a single actuator unit 21 corresponds, are - from the lower side of 8th - Starting two pressure chamber rows 11a and two pressure chamber rows 11b arranged next to the upper side of the pressure chamber rows 11a are located. The four pressure chamber rows from the two pressure chamber rows 11a and the two pressure chamber rows 11b form a group of pressure chamber rows. Such a group of pressure chamber rows is, starting from the lower side in the ink ejection area, that of a single actuator unit 21 corresponds - repeatedly arranged three times. A straight line through the top acute-angled section of each pressure chamber in each row of pressure chambers 11a and 11b runs, crosses the lower oblique side of each pressure chamber in the pressure chamber row adjacent to the upper side of this pressure chamber row.

As described above, if you are perpendicular to 8th looks - two first pressure chamber rows 11a and two pressure chamber rows 11b in those with pressure chambers 10 connected nozzles are arranged at different positions, arranged alternately side by side. Consequently, as a whole, the pressure chambers are 10 arranged regularly. On the other hand, nozzles are concentrated in a central area of each group of pressure chamber rows formed by the above-mentioned four rows of pressure chambers. In the case where four rows of pressure chambers each form a group of rows of pressure chambers and such a group of rows of pressure chambers is repeatedly arranged three times, starting from the lower side, as described above, a nozzle-free area thus arises in the immediate vicinity of the boundary between adjacent groups of pressure chamber rows, ie on both sides of each group of pressure chamber rows, which consists of four pressure chamber rows. Wide sub-distribution channels 5a extend there to supply ink to the respective pressure chambers 10 , In this ink jet head, in the ink ejection area, that of a single actuator unit 21 corresponds to a total of four wide sub-distribution channels 5a arranged in the first arrangement direction, one on the lower side of 8th one between the lowest group of pressure chamber rows and the second-lowest group of pressure chamber rows and two on both sides of the uppermost group of pressure chamber rows.

Let us turn 8th to. Nozzles with ink ejection openings 8th for spraying ink in fluid communication are in the first arrangement direction at regular intervals of 50 dpi arranged so that they correspond to the respective pressure chambers 10 which are arranged regularly in the first arrangement direction. On the other hand - while twelve pressure chambers 10 are also arranged regularly in the second arrangement direction and form an angle θ to the first arrangement direction - contain twelve nozzles, which are the twelve pressure chambers 10 correspond, respectively, with each of the upper acute-angled portion of the corresponding pressure chamber 10 are in fluid communication, and those respectively with the lower acute-angled portion of the corresponding pressure chamber 10 are in fluid communication, which is why they are not regularly arranged in the second arrangement direction at regular intervals.

If all nozzles are located on the same side acute-angled sections of the respective pressure chambers 10 are in fluid communication, so the nozzles are arranged regularly in the second arrangement direction at regular intervals. In this case, the nozzles are arranged so as to shift in the first arrangement direction by a distance corresponding to a printing resolution of 600 dpi per printing chamber row - from the lower side to the upper side of FIG 8th - corresponds. Quite different is in this inkjet head - because four pressure chamber rows of two pressure chamber rows 11a and two pressure chamber rows 11b form a group of pressure chamber rows and such a group of pressure chamber rows is repeatedly arranged three times from the lower side; the displacement of the nozzle position in the first arrangement direction per pressure chamber row from the lower side to the upper side of FIG 8th not always the same.

It becomes a band area R in the ink-jet head 1 which has a width (about 508.0 μm) corresponding to 50 dpi in the first arrangement direction and extends perpendicular to the first arrangement direction. In this band area R, each of twelve rows of pressure chambers contains only a single nozzle. That is, when such a band region R is at an optional position in the ink ejection region of a single actuator unit 21 is defined, so are always twelve nozzles distributed in the band region R. The positions of dots each obtained by projecting the twelve nozzles on a straight line extending in the first arranging direction are removed from each other by a distance corresponding to a printing resolution of 600 dpi.

When the twelve nozzles contained in a single band region R are sequentially driven from a nozzle whose image projected on a straight line extending in the first arrangement direction is leftmost (1) to (12) be designated, so the twelve nozzles in order (1) . (7) . (2) . (8th) . (5) . (11) . (6) . (12) . (9) . (3) . (10) and (4) - Starting from the bottom side - arranged.

In the thus constructed ink jet head 1 can by properly driving the active layers in the actuator unit 21 a letter or a number, a figure or the like can be made with a resolution of 600 dpi. That is, by selectively driving active layers corresponding to the twelve rows of printing chambers sequentially in accordance with the conveyance of a printing medium, a specific letter, number, or figure can be printed on the paper.

By way of example, a case will be described in which a straight line extending in the first arrangement direction is printed at a resolution of 600 dpi. First, a case will be briefly described in which nozzles are provided with the acute-angle portions of pressure chambers on the same side 10 be in fluid communication. In this case, in accordance with the transportation of a paper, the ink ejection starts with a nozzle in the lowermost row of pressure chambers 8th , The ink ejection then shifts upward selecting a nozzle sequentially associated with the upper adjacent pressure chamber row. As a result, ink dots in the first arrangement direction which are adjacent to each other at 600 dpi are formed sequentially. Finally, all ink dots form a straight line extending in the first arrangement direction with a resolution of 600 dpi.

On the other hand, in this ink jet head, the ink ejection starts with a nozzle in the lowermost row of pressure chambers 11a in 8th and the ink ejection then shifts upward, with a nozzle in fluid communication with the upper adjacent row of pressure chambers sequentially being selected in accordance with the conveyance of a pressure medium. In this embodiment, however, because the positional shift of nozzles in the first arrangement direction per pressure chamber row from the lower side to the upper side are not always the same, ink dots are formed in order in the first arrangement direction in accordance with the conveyance of a printing medium , not arranged at regular intervals of 600 dpi.

More precisely, will - as in 8th shown, and in accordance with the transport of a print medium - ink first through a nozzle (1) with the lowest pressure chamber row 11a in 8th is in fluid communication, injected, to form a dot row on the print media at intervals equal to 50 dpi (about 508.0 μm). Subsequently, while the printing medium is being conveyed, and the position when forming the straight line is the position of a nozzle (7) has reached that with the second-lowest pressure chamber row 11a is in fluid communication - ink through the nozzle (7) spouted. The second ink dot is thereby formed at a position shifted from the first formed dot position in the first arrangement direction by a distance of six times the pitch corresponding to 600 dpi (about 42.3 μm) (about 42.3 μm × 6 = about 254.0 μm).

Then, when the printing medium is further transported and the position when forming the straight line, the position of a nozzle (2) that with the third-lowest pressure chamber row 11b in fluid communication has reached, so ink is through the nozzle (2) spouted. The third ink dot is thereby formed at a position shifted from the first formed dot position in the first arrangement direction by a distance of the distance corresponding to 600 dpi (about 42.3 μm). Then, when the printing medium is further transported and the position when forming the straight line, the position of a nozzle (8th) , with the fourth-bottom row of pressure chambers 11b in fluid communication has reached, so ink is through the nozzle (8th) spouted. The fourth ink dot is thereby formed at a position shifted from the first formed dot position in the first arrangement direction by a distance of seven times the pitch, which is 600 dpi (about 42.3 μm) (about 42.3 μm × 7 = about 296.3 μm). Then, when the printing medium is further transported and the position when forming the straight line, the position of a nozzle (5) , those with the fifth lowest pressure chamber row 11a in fluid communication has reached, so ink is through the nozzle (5) spouted. The fifth ink dot is thereby formed at a position shifted from the first formed dot position in the first arrangement direction by a distance of four times the pitch, which is 600 dpi (about 42.3 μm) (about 42.3 μm × 4 = about 169.3 μm).

Thereafter, ink dots are formed in the same manner, with nozzles being selected which are equipped with pressure chambers 10 in turn from the lower side to the upper side in 8th be in fluid communication. If in this case the number of a nozzle in 8th is equal to N, an ink dot is formed at a position shifted from the first formed dot position in the first arrangement direction by a distance corresponding to (magnification n = N-1) × (pitch corresponding to 600 dpi). When the twelve nozzles have finally been selected, the gap between the ink dots passing through the nozzles becomes (1) in the lowest pressure chamber rows 11a in 8th at a pitch corresponding to 50 dpi (about 508.0 μm) are filled with eleven dots formed at intervals corresponding to 600 dpi (about 42.3 μm). Therefore, as a whole, a straight line extending in the first arrangement direction can be drawn at a resolution of 600 dpi.

Next, the sectional structure of the ink-jet head will be described 1 described. 9 is a partially exploded view of the head main body 1a from 4 , 10 is an enlarged sectional view with a side view of the area, which in 7 is delimited with a dot-dash line. Let us turn to that 7 and 9 to. A main section at the bottom of the inkjet head 1 has a layer structure consisting of a total of ten laminated layers of material, from the top: an operating unit 21 , a cavity plate 22 , a base plate 23 , an opening plate 24 , a feed plate 25 , Distribution plates 26 . 27 and 28 , a cover plate 29 and a nozzle plate 30 , Of these, nine plates form - with the exception of the operating unit 21 - a passage unit 4 ,

As will be described in more detail below, the actuating unit 21 from five piezoelectric layers 41 to 45 laminated (see 10 ), and is provided with electrodes such that only the uppermost layer and the second layer adjacent to the uppermost layer contain portions that are active when an electric field is applied (hereinafter referred to simply as "active layer layers") ), and the remaining three layers are inactive. The cavity plate 22 consists of metal, in which a large number of substantially rhombic openings are formed, which are the respective pressure chambers 10 correspond. The base plate 23 is made of metal, in which a flow hole between each pressure chamber 10 the cavity plate 22 and the corresponding opening 12 and a flow hole between the pressure chamber 10 and the corresponding ink ejection opening 8th are formed. The orifice plate 24 is made of metal in which - in addition to openings 12 - Flow holes for connecting each pressure chamber 10 the cavity plate 22 with the corresponding ink ejection opening 8th are formed. The feed plate 25 is made of metal, in which flow holes between each opening 12 and the corresponding sub-distribution channel 5a and flow holes for connecting each pressure chamber 10 the cavity plate 22 with the corresponding ink ejection opening 8th are formed. Each of the distribution plates 26 . 27 and 28 is made of metal, which is an upper section of each sub-distribution channel 5a defined and in the Strö tion holes for connecting each pressure chamber 10 the cavity plate 22 with the corresponding ink ejection opening 8th are formed. The cover plate 29 consists of metal, in the flow holes for connecting each pressure chamber 10 the cavity plate 22 with the corresponding ink ejection opening 8th are formed. The nozzle plate 30 is made of metal, in which tapered ink ejection openings 8th , each acting as a nozzle, for the respective pressure chambers 10 the cavity plate 22 are formed.

These ten layers 21 to 30 are laid in layers that are positioned to each other so that an ink passage 32 is formed as he is in 6 is illustrated. The ink passage 32 extends first from the sub-distribution channel 5a upwards, then extends horizontally in the opening 12 , then extends further upwards, then again extends horizontally in the pressure chamber 10 , then extends obliquely downwards in a certain length from the opening 12 and then extends vertically downwards toward the ink ejection port 8th ,

Let us turn 10 to. The operating unit 21 contains five piezoelectric layers 41 . 42 . 43 . 44 and 45 with the same thickness of about 15 microns. These piezoelectric layers 41 to 45 are formed into a continuous layered flat plate (continuous flat layers) which is arranged to extend over many pressure chambers 10 that extends within a single ink ejection area in the inkjet head 1 are formed. Because the piezoelectric layers 41 to 45 are arranged so that they are over many pressure chambers 10 As the continuous flat layers extend, the individual electrodes can 35a and 35b be arranged with a high density, for example by means of a screen printing technique. That's why the pressure chambers can 10 , which are formed at positions that the individual electrodes 35a and 35b be arranged with a high density. This makes it possible to print a high resolution image. In this embodiment, each of the piezoelectric layers 41 to 45 of a lead zirconate titanate (PZT) -based ceramic material having ferroelectricity.

Between the topmost piezoelectric layer 41 and the piezoelectric layer 42 extending in the downward direction next to the piezoelectric layer 41 is an approximately 2 microns thick common electrode 34a formed on the entire lower and upper sides of the piezoelectric layers. Furthermore, between the piezoelectric layer 43 extending in the downward direction next to the piezoelectric layer 42 located, and the piezoelectric layer 44 extending in the downward direction next to the piezoelectric layer 43 located, about 2 microns thick common electrode 34b arranged like the common electrode 34a is trained. On top of the piezoelectric layer 41 is an approximately 1 micron thick single electrode 35a designed to fit any pressure chamber 10 corresponds (see 6 ). The single electrode 35a has - viewed from above - a similar shape (length: 850 microns, width: 250 microns) as the pressure chamber 10 , so that a projection image of each electrode 35a along the thickness direction of each electrode 35a is projected in the appropriate pressure chamber 10 is included. Furthermore, between the piezoelectric layers 42 and 43 an approximately 2 μm thick single electrode 35b arranged like the single electrode 35a is trained. Between the piezoelectric layer 44 extending in the downward direction next to the piezoelectric layer 43 located, and the piezoelectric layer 45 extending in the downward direction next to the piezoelectric layer 44 located, as well as on the bottom of the piezoelectric layer 45 there is no electrode. Each of the electrodes 34a . 34b . 35a and 35b For example, it is made of an Ag-Pd-based metallic material.

The common electrodes 34a and 34b are grounded in a non-illustrated area. Thus, the common electrodes 34a and 34b in a range of any pressure chamber 10 corresponds to the earthing potential. The individual electrodes 35a and 35b in each pair, that of a pressure chamber 10 are independent of another pair of individual electrodes with (non-illustrated) lead wires that are within the FGS 136 are in contact so that the potential of each pair of individual electrodes can be controlled independently of the other pair. The individual electrodes 35a and 35b are via the connecting wires to the driving IC 132 connected. In this case, the individual electrodes 35a and 35b in each pair, which are arranged vertically, with the driving IC 132 be connected via the same connection line. In a modification, many pairs of common electrodes 34a and 34b each having a shape larger than that of a pressure chamber 10 such that the projection image of each common electrode projected in the thickness direction of the common electrode may include the pressure chamber for each pressure chamber 10 to be available. In a further modification, many pairs of common electrodes can be used 34a and 34b , each having a shape that is slightly smaller than that of a pressure chamber 10 such that the projection image of each common electrode projected in the thickness direction of the common electrode may be contained in the pressure chamber for each pressure chamber 10 to be available. Thus, the common electrode needs 34a or 34b not always being a single conductive layer formed on the entire surface of a piezoelectric layer. In the above modifications, however, all common electrodes must elek be connected to each other so that the section of any pressure chamber 10 matches, is at the same potential.

In the inkjet head 1 are the piezoelectric layers 41 to 45 polarized in their thickness direction. That is, the operating unit 21 has a so-called unimorph structure, in which the upper (ie of the pressure chamber 10 distant) three piezoelectric layers 41 to 43 Layers are where there are active layers and the lower ones (ie near the pressure chamber 10 located) two piezoelectric layers 44 and 45 are formed as inactive layers. If the individual electrodes 35a and 35b in a pair are set to a positive or a negative predetermined potential and, for example, when the polarization is in the same direction as the electric field, so the portion under the influence of the electric field functions in the piezoelectric layers 41 to 43 which is disposed between the common and the individual electrodes as an active layer (pressure generating portion) and contracts perpendicular to the polarization by the transverse piezoelectric effect. Because on the other hand, the piezoelectric layers 44 and 45 are not affected by an electric field, they do not contract in themselves. This results in a mechanical voltage difference perpendicular to the polarization between the upper piezoelectric layers 41 to 43 and the lower piezoelectric layers 44 and 45 , As a result, the entire piezoelectric layers are 41 to 45 ready to deform into a convex shape towards the inactive side (unimorphic deformation). At this time, as in 10 is the lowest side of the piezoelectric layers 41 to 45 at the top of the partition (the cavity plate) 22 , the pressure chambers separated from each other, fixed, and as a result deforms the pie zoelektrischen layers 41 to 45 to a convex shape in the direction of the pressure chamber side. That is why the volume of the pressure chamber 10 reduced to increase the pressure of the ink. The ink is thereby passed through the ink ejection port 8th spouted. After that, if the individual electrodes 35a and 35b to the same potential as that of the common electrodes 34a and 34b are returned, the piezoelectric layers return 41 to 45 back to the original shape, and the pressure chamber 10 also returns to its original volume. Thus, the pressure chamber sucks 10 Ink through the distribution channel 5 in.

In a further driving method, all individual electrodes 35a and 35b previously set to a different potential than that of the common electrodes 34a and 34b , When an ejection request is issued, the corresponding pair of individual electrodes becomes 35a and 35b once set to the same potential as that of the common electrodes 34a and 34b , Thereafter, at a given timing, the pair of individual electrodes 35a and 35b again to a different potential than that of the common electrodes 34a and 34b set. In this case, sweep at the time when the pair of individual electrodes 35a and 35b set to the same potential as that of the common electrodes 34a and 34b , the piezoelectric layers 41 to 45 back to their original forms. The volume of the corresponding pressure chamber 10 is thereby increased from its initial state (the state where the potentials of both electrodes are different from each other) to ink from the distribution channel 5 in the pressure chamber 10 to suck. After that, at the time when the pair of individual electrodes deform 35a and 35b back to the other potential compared to the potential of common electrodes 34a and 34b is set, the piezoelectric layers 41 to 45 to a convex shape in the direction of the pressure chamber 10 , The volume of the pressure chamber 10 is thereby reduced, and the pressure of the ink in the pressure chamber 10 increases to spit out the ink.

On the other hand, if the polarization is in the reverse direction than the direction of the electric field applied to the piezoelectric layers 41 to 43 is applied, then the active layers are in the piezoelectric layers 41 and 42 that lie between each electrode 35a and 35b and the common electrodes 34a and 34b ready to be perpendicular to the polarization by the transverse piezoelectric effect to length. As a result, the piezoelectric layers deform 41 to 45 to a concave shape in the direction of the pressure chamber 10 , That is why the volume of the pressure chamber 10 enlarged to ink from the distribution channel 5 to suck. After that, if the individual electrodes 35a and 35b To return to their original potential, the piezoelectric layers also return 41 to 45 back to its original flat shape. The pressure chamber 10 thereby returns to its original volume to ink through the ink ejection opening 8th eject.

Next, a manufacturing method of the ink jet head will be described 1 described.

For the production of the ink jet head 1 become a passage unit 4 and each operating unit 21 made separately in parallel, and then both are bonded together. For the production of the passage unit 4 is every plate 22 to 30 from which the passage unit 4 etched using a patterned photoresist as a mask, leaving openings as in the 7 and 9 are illustrated in the ever like plates 22 to 30 be formed. After that, the nine plates 22 to 30 in such a way with layers of adhesives applied to layers that ink passages 32 arise in it. The nine plates 22 to 30 are thereby interconnected, so that a passage unit 4 arises.

For making each actuator 21 First, a conductive paste that acts as a single electrode 35b should act in a pattern printed on a ceramic green layer, acting as a piezoelectric layer 43 should serve. In parallel, conductive pastes are used as common electrodes 34a and 34b should serve in a pattern printed on ceramic green sheets, which are called piezoelectric layers 42 and 44 should serve. After that, five green layers are created as piezoelectric layers 41 to 45 to serve, laid into layers and clamped in a jig. The layer structure thus obtained is then fired at a predetermined temperature. Thereafter, individual electrodes 35a on the piezoelectric layer 41 formed of the fired layer structure. For example, the individual electrodes 35a be formed in such a way that a conductive film on an entire surface of the piezoelectric layer 41 is plated and then removed unnecessary portions of the conductive film by means of laser structuring. Alternatively, the individual electrodes 35a by depositing a conductive film on the piezoelectric layer 41 by means of PVD (Physical Vapor Deposition) using a mask with openings at sections that correspond to the individual electrodes 35a correspond, be trained. Until this process is the production of the actuator unit 21 completed.

Next, the operating unit made as described above 21 so with an adhesive to the passage unit 4 glued that to the piezoelectric layer 45 with the cavity plate 22 can be in contact. At this time, both are based on position marks on the surface of the cavity plate 22 the passage unit 4 or on the surface of the piezoelectric layer 41 are arranged, bonded together.

Thereafter, through holes are formed to vertically arranged corresponding individual electrodes 35a and 35b to connect with each other. The through holes are then filled with a conductive material. Thereafter, for the purpose of applying electrical signals to the individual electrodes 35a and 35b and the common electrodes 34a and 34b the FGS 136 to the bonding positions that correspond to the respective electrodes on the actuator unit 21 correspond, soldered and so electrically connected to them. Thereafter, the production of the ink jet head 1 completed by a given process.

As described above, in contrast to the other electrodes, the only individual electrodes 35a not with the ceramic materials to piezoelectric layers 41 to 45 burned. The reason is that because the individual electrodes 35a are free, they can evaporate at high firing temperature. As a result, its thickness is difficult to compare with the other electrodes 34a . 34b and 35b steered with ceramic materials. But even the thickness of the other electrodes 34a . 34b and 35b may lose weight when burning. Therefore, it is difficult to form them with a small thickness, considering the maintenance of continuity after firing. Because, in contrast, the individual electrodes 35a after firing by the technique described above, they can be formed with a smaller thickness than the other electrodes 34a . 34b and 35b , Thus, in the ink jet head 1 when the individual electrodes 35a be formed in the uppermost layer with a smaller thickness than the other electrodes 34a . 34b and 35b , the deformation of the piezoelectric layers 41 to 43 , which contain active layers, hardly by the individual electrodes 35a be limited. This will increase the efficiencies (electrical efficiency and area efficiency) of the actuator 21 improved.

Because in the inkjet head 1 the piezoelectric layers 41 to 43 containing active layers and the piezoelectric layers 44 and 45 that act as the inactive layers are made of the same material, the material need not be changed during the manufacturing process. Thus, they can be produced by a relatively simple process, which can be expected to reduce the manufacturing cost. In addition, due to the fact that each of the piezoelectric layers 41 to 43 containing active layers and the piezoelectric layers 44 and 45 that act as the inactive layers, have substantially the same thickness, by further simplifying the manufacturing process, to further reduce costs. This is because the thickness control can be easily accomplished when the ceramic materials to be used as the piezoelectric layers are layered.

Further, in the ink jet head 1 separate actuators 21 corresponding to the respective ink ejecting areas, so to the passage unit 4 Bonded in the longitudinal direction of the passage unit 4 are arranged. That is why each of the operating units 21 that in the dimensional accuracy and the position accuracy of the individual electrodes 35a . 35b could be uneven because they are made by sintering or the like, regardless of another actuator unit 21 at the passage unit 4 be positioned. Thus, even in the case of a long head, the increase in displacement of each operating unit becomes 21 from the exact position on the passage unit 4 restricted, and both can be precisely positioned to each other. Therefore, even with regard to individual electrodes 35a and 35b which are relatively distant from a mark, the individual electrodes 35a and 35b not significantly from the predetermined position on the corresponding pressure chamber 10 be moved. As a result, good ink ejection results can be obtained and the production yield of the ink-jet heads 1 is significantly increased. On the other hand, and in contrast to the above, is - if a long-shaped actuator unit 21 like the passage unit 4 is produced - the displacement of the individual electrodes 35a and 35b from the predetermined position on the corresponding pressure chamber 10 - viewed from above - the larger, the farther the individual electrodes 35a and 35b are removed from the mark when the actuator unit 21 over the passage unit 4 is placed. As a result, the ink ejection results become a pressure chamber 10 That is, the uniformity of the ink spouting results of the ink jet head 1 is not achieved.

In addition, in the ink-jet head constructed as described above 1 by arranging the piezoelectric layers 41 to 43 between the common electrodes 34a and 34b and the individual electrodes 35a and 35b the volume of each pressure chamber 10 be easily changed by the piezoelectric effect. Because, furthermore, each of the piezoelectric layers 41 to 43 containing active layers, in the form of a continuous flat layer, are easy to manufacture.

Furthermore, the inkjet head 1 the actuators 21 each having a unimorph structure, the piezoelectric layers 44 and 45 near each pressure chamber 10 are inactive and the piezoelectric layers 41 to 43 from each pressure chamber 10 are removed, containing active layers. That's why changing the volume of each pressure chamber 10 amplified by the transverse piezoelectric effect. As a result, as compared with an ink jet head in which a layer containing active layers, on the side of the pressure chamber 10 is arranged and an inactive layer is disposed on the opposite side, a reduction in the voltage applied to the individual electrodes 35a and 35b is to create, and / or a high integration of the pressure chambers 10 to be sought. By lowering the voltage to be applied, the driver for driving the individual electrodes 35a and 35b be made smaller and the costs can be kept low. In addition, every pressure chamber 10 be built smaller. Furthermore, even in the case of high integration of the pressure chambers 10 a sufficient amount of ink to be injected. Thus, a reduction of the head 1 and a high-density arrangement of printing dots can be realized.

Furthermore, in the ink jet head 1 each actuation unit 21 a substantially trapezoidal shape. The actuators 21 are arranged zigzag in two rows so that the parallel opposite sides of each actuator 21 in the longitudinal direction of the passage unit 4 extend and the oblique sides of each adjacent actuator unit 21 each other in the lateral direction of the passage unit 4 overlap.

Because the oblique sides of each adjacent operating units 21 overlap each other in this way, when the ink jet head 1 in the lateral direction of the ink jet head 1 moved relative to a pressure medium - the pressure chambers 10 in the lateral direction of the passage unit 4 compensate each other. As a result, a small inkjet head 1 be realized with a very narrow width and simultaneously high-resolution printing.

Because in addition many pressure chambers 10 , which are next to each other, in the passage unit 4 arranged in a matrix, can the many pressure chambers 10 be arranged within a relatively small size with a high density.

In the above-described ink jet head 1 Trapezoidal actuators are arranged in two rows zigzag. But it does not take every actuator to be trapezoidal. Furthermore, actuator units also need to be arranged in only a single row in the longitudinal direction of the passage unit. Actuators may be arranged zigzag in three or more rows.

Next, a second embodiment of the present invention will be described. 11 Fig. 10 is a plan view of a head main body of an ink jet head according to this embodiment. In the ink jet head and the ink jet printer according to this embodiment, since the parts other than the head main body are similar to those of the first embodiment described above, the detailed description thereof will be omitted tet.

Let us turn 11 to. A head main body 201 An ink jet head according to this embodiment has a rectangular shape as viewed from above, which extends in one direction (main scanning direction). The head main body 201 contains a passage unit 204 in which a large number of pressure chambers 210 and a large number of ink ejection openings 208 are formed, as will be described below. On the top of the passage unit 204 are two parallelogram-shaped actuators 221 (in 11 are the right and the left with the reference numbers 221a respectively. 221b designated) bonded side by side. Each actuation unit 221 is arranged so that its one side B in the longitudinal direction of the head main body 201 extends. The adjacent actuators 221 are arranged to be along the width direction (the shorter-length direction) of the head main body 201 are aligned with their oblique sides C close to each other. An ink supply port 202 is in the top of the passage unit 204 open. The ink supply port 202 is connected to an ink supply source via a passage (not illustrated).

Let us turn 12 to which is a view of the head main body 201 in one compared to 11 inverted viewing angle (a view from the printing surface side). Two parallelogram ink ejection areas R1 are in the bottom of the passage unit 204 arranged so that they correspond to the respective areas where the operating units 221 are arranged. A large number of ink ejection openings 208 small diameter are arranged in the surface of each ink ejection area R1.

This embodiment shows a case of a single-color printing. The ink supply port 202 Ink is supplied with a single color (for example, black). To perform multi-color printing, head main bodies 201 whose number corresponds to the number of colors (for example, in the case of the four colors yellow, cyan, magenta and black, four head main bodies 201 ), aligned in the lateral direction of the passage unit. The head main bodies 201 different color inks are fed to each other for printing.

13 is a sectional view showing the internal structure of the passage unit 204 illustrated. Let us turn 13 to where a distribution channel 205 in the passage unit 204 is trained. The distribution channel 205 stands over the ink supply port 202 in fluid communication with an ink supply source, which is why the distribution channel 205 always filled with ink. The ink supply port 202 is preferably provided with a filter for collecting dust and dirt contained in the ink.

The distribution channel 205 is in the majority of the passage unit 204 is formed to extend over the two ink ejecting areas R1. In a part of the distribution channel 205 that corresponds to each ink ejection area R1 is a large number of narrow parallelogram-shaped island portions 205a designed such that they are arranged at regular intervals. The length of each island section 205a runs in the longitudinal direction of the passage unit 204 , In this structure, ink flows through the ink supply port 202 is supplied between all adjacent island sections 205a in the distribution channel 205 and then becomes pressure chambers (described below) 210 distributed in the passage unit 204 are formed in each ink ejection area R1.

Let us turn 15 to. Each ink ejection opening 208 is formed as a tapered nozzle. The ink ejection opening 208 is above a pressure chamber 210 having a substantially parallelogram-like shape when viewed from above, and an opening 212 with a distribution channel 205 in fluid communication. In this construction, ink from the distribution channel becomes 205 over the opening 212 to the pressure chamber 210 guided. By driving an actuating unit 221 As will be described later, beam energy is applied to the ink in the pressure chamber 210 applied to the ink through the ink ejection port 208 to spray in a jet.

14 FIG. 12 illustrates a detailed structure of the area included in FIG 13 designated by the reference Q. How out 14 can be seen are in an area of the top of the passage unit 204 that corresponds to an ink ejection area R1, a large number of pressure chambers 210 arranged side by side in a matrix. Because the pressure chambers 210 formed on a different plane than the openings 212 , as in 15 is an arrangement as shown in FIG 14 illustrated, possible, in the every opening 212 that with a pressure chamber 210 connected, another pressure chamber 210 overlaps. As a result, a high-density arrangement of the pressure chambers 210 be realized, resulting in a reduction of the head main body 201 and an increase in the resolution of an image to be produced.

15 illustrates a concrete construction of a passage from a distribution channel 205 to a Tintenaus injection opening 208 , Let us turn 15 to. The passage unit 204 is out of all laminated together with nine layers of material, namely a cavity plate 222 , a base plate 223 , an orifice plate 224 , a feeder plate 225 , Distribution plates 226 . 227 and 228 , a cover plate 229 and a nozzle plate 230 , The above-described actuators 221 are at the top of the passage unit 204 bonded, leaving a head main body 201 arises. The detailed structure of each actuator 221 will be described below.

A parallelogram-shaped opening is in the cavity plate 222 designed so that a pressure chamber 210 is formed as described above. A tapered ink ejection port 208 is using a press in the nozzle plate 230 educated. Through each of the plates 223 to 229 through are flow holes 251 between the plates 222 and 230 educated. The pressure chamber 210 stands over the flow holes 251 with the ink ejection opening 208 in fluid communication. In the opening plate 224 is an opening 212 designed as a slot. One end of the opening 212 is over a flow hole 252 that in the base plate 223 is formed with an end portion of the pressure chamber 210 (opposite to the end portion connected to the ink ejection port 208 connected). The opening 212 is used to properly control the amount of ink that the pressure chamber 210 is to be supplied, and preventing too much or too little ink through the ink ejection opening 208 is injected. In the feed plate 225 is a flow hole 253 educated. The flow hole 253 connects the other end of the opening 212 with the distribution channel 205 ,

Each of the nine plates 222 to 230 that the passage unit 204 form, consists of metal. The pressure chamber 210 , the opening 212 and the flow holes 251 . 252 and 253 are formed by selectively etching each metal plate by means of a mask pattern. The nine plates 222 to 230 are arranged in layers and bonded to each other, whereby they are positioned to each other so that therein in 15 illustrated passage is formed.

Let us turn 16 to. Each actuation unit 221 contains five piezoelectric layers 241 to 245 with the same thickness of about 15 microns. These piezoelectric layers 241 to 245 are formed as continuous flat layers. A single actuator unit 221 is arranged so that it is over many pressure chambers 210 which extends in a single ink ejection area R1 of the head main body 201 are formed. This allows a high-density arrangement of individual electrodes 235a and 235b in the operating unit 221 will be realized. Each of the piezoelectric layers 241 to 245 consists of a lead zirconate titanate (PZT) based ceramic material with ferroelectricity.

Between the first and second piezoelectric layers 241 and 242 - Seen from above - is about 2 microns thick common electrode 234a arranged, which is formed substantially on the entire lower and upper sides of the piezoelectric layers. Furthermore, between the third and the fourth piezoelectric layer 243 and 244 an approximately 2 μm thick common electrode 234b arranged. On top of the first piezoelectric layer 241 is an approximately 1 micron thick single electrode 235a according to each pressure chamber 210 educated. As in 13 Illustrated has the single electrode 235a - viewed from above - a similar shape as the pressure chamber 210 although the single electrode 235a a little smaller than the pressure chamber 210 , The single electrode 235a is arranged so that the middle of each electrode 235a with the middle of the corresponding pressure chamber 210 matches. Furthermore, between the second and the third piezoelectric layer 242 and 243 an approximately 2 μm thick single electrode 235b arranged like the single electrode 235a is shaped. The section where the individual electrodes 235a and 235b are arranged, corresponds to a pressure generating section A for applying a pressure to the ink in the pressure chamber 210 , Between the fourth and the fifth piezoelectric layer 244 and 245 and on the bottom of the fifth piezoelectric layer 245 there is no electrode. Each of the electrodes 234a . 234b . 235a and 235b For example, it is made of an Ag-Pd-based metallic material.

The common electrodes 234a and 234b are grounded in a non-illustrated area. Thus, the common electrodes 234a and 234b in a range of any pressure chamber 210 corresponds to the earthing potential. Thus the potential of the individual electrodes 235a and 235b in each pair, that of a pressure chamber 210 which can be controlled independently of another pair, they are connected via a connecting lead, which is used for each pair of individual electrodes 235a and 235b is separate, connected to a suitable drive IC.

In the head main body 201 are the piezoelectric layers 241 to 245 to polarize in thickness. That is, the operating unit 221 has a so-called unimorph structure, in which the upper (ie of the pressure chamber 210 distant) three piezoelectric layers 241 to 243 Layers are those containing active layers and the lower ones (ie near the pressure chamber 210 located) two piezoelectric layers 244 and 245 are formed as inactive layers.

If in this construction the individual electrodes 235a and 235b are set to a positive or a negative predetermined potential in a pair and, for example, when the polarization is in the same direction as the electric field, the portion (an active layer, ie, a pressure generating portion) contracts in the piezoelectric sheets 241 to 243 which is located between the common and the individual electrodes, perpendicular to the polarization together. Because on the other hand, the inactive piezoelectric layers 244 and 245 are not affected by any electric field, they do not contract in themselves. Thus, along the polarization, a mechanical stress difference arises between the upper piezoelectric layers 241 to 243 and the lower piezoelectric layers 244 and 245 , As a result, the entire piezoelectric layers are 241 to 245 ready to deform into a convex shape towards the inactive side (unimorphic deformation). Because the bottom of the bottom piezoelectric layer 245 at the top of the dividing wall, which houses the pressure chambers 210 separates, fixed, deforms at this time, the pressure generating section A of the piezoelectric layers 241 to 245 to a convex shape toward the side of the pressure chamber 210 to the volume of the pressure chamber 210 to downsize. As a result, the pressure of the ink increases, whereby ink through the ink ejection opening 208 is injected. After that, applying the drive voltage to the individual electrodes 235a and 235b is terminated, so turn the piezoelectric layers 241 to 245 back to the original shape, and the pressure chamber 210 also returns to its original volume. Thus, the pressure chamber sucks 210 Ink over the distribution channel 205 in.

Next, the shape of the two actuator units 221a and 221b and the arrangement of individual electrodes 235a and 235b (or in other words, the arrangement of the pressure generating sections A) described. 17 illustrates the shape of an actuator unit 221a and the arrangement of pressure generating sections. 18 shows the relationship between a seam portion between the operating units 221a and 221b and pressure generating sections in an additional area.

The head main body 201 contains two operating units 221a and 221b , as described above. The two operating units 221a and 221b have quite similar shapes and the same arrangement of the pressure generating sections A.

As in the 11 and 17 Illustrated is the actuator unit 221a parallelogram-shaped and is arranged so that its one side B parallel to the longitudinal direction of the passage unit 204 runs and its other side C obliquely to the longitudinal direction of the passage unit 204 runs. As in 17 illustrated in the actuator unit 221a two areas P1 and P2, which are in the lateral direction of the passage unit 204 by a straight line in the longitudinal direction of the passage unit 204 are separated. That is, the areas P1 and P2 are in the lateral direction of the passage unit 204 side by side.

In the base region P1 of the two regions P1 and P2, a large number of pressure generating sections A1 are juxtaposed in a matrix in the longitudinal direction of the passage unit 204 and arranged along the other side C of the parallelogram.

In the other area (the additional area P2) than the base area P1, pressure generating sections A2 are juxtaposed in a matrix only in the immediate vicinity of an acute-angled corner D of the parallelogram near the operating unit 221b arranged.

If, as in 18 illustrates the thus constructed two actuator units 221a and 221b in series in the longitudinal direction of the passage unit 204 are arranged as in 11 Fig. 11 illustrates the pressure generating sections A2 of the additional area P2 included in the operating unit 221a is disposed at a position corresponding to an area (the hatched area G in FIG 18 ) where no pressure generating section A may be located in the base region P1 because it is in the seam between the operating units 221a and 221b located. That is, the pressure generating portions A2 of the additional area P2 are arranged to correspond to a gap portion G between the pressure generating portions A1 of the base portion P1 located in the operating unit 221a and the pressure generating sections A1 of the base area P1 located in the adjacent operation unit 221b is, correspond. Thus, although there is no separate operation unit for spouting ink through the gap portion G, a head main body 201 be provided, which can print without interruption over the entire longitudinal direction of the passage unit.

In other words, because in the area (area G) near the seam portion between the operating units 221a and 221b no pressure generating section can be arranged, can also no pressure chamber 210 and no ink ejection opening 208 be arranged in this area. Thus, if the pressure generating sections A2 are not in the additional area P2 located in the operating unit 221a is located, ange ordered, printing in the section corresponding to the gap section G would not be possible. As a result, a portion where ink can not be ejected would be in the seam portion between the actuator units 221a and 221b arise. But because the pressure generating sections A2 in the additional area P2, located in the operating unit 221a If there are arranged in a portion overlapping that area G in the lateral direction of the passage unit, there is no portion where the ejection of ink is impossible. As a result, a picture can be made without interruption on a paper.

As described above, in this embodiment, the operation unit includes 221 Rows, in each of which a large number of pressure generating sections A1 and A2 in the longitudinal direction of the passage unit 204 are arranged. What the lengths of these rows in the longitudinal direction of the passage unit 204 As far as is concerned, each row in the base area P1 is longer than each row in the additional area P2. What further, the number of rows in the lateral direction of the passage unit 204 As far as the number of rows in the additional area P2 is the same as the number of rows in the length of the corresponding area G in the lateral direction of the passage unit 204 could be present. Thus, when an imaginary straight line is drawn, that in the lateral direction of the passage unit 204 is the number of rows that intersects the imaginary straight line in the area where the adjacent actuator units 221a and 221b overlap each other, the same surface as the number of rows, which intersects the imaginary straight line in the area where the adjacent actuator units 221a and 221b do not overlap each other.

The above-described feature can only be achieved by using two actuator units 221a and 221b with the same structure. Thus, the arrangement of parts can be simplified, and the cost and number of process steps necessary for designing or manufacturing the actuator units 221a and 221b necessary can be reduced.

The arrangement of pressure generating sections A in the operating unit 221 described in this embodiment is just one example. For example, an actuator unit 255 as they are in 19 is illustrated. 19 illustrates another example of the arrangement of pressure generating sections in an actuator. 20 FIG. 14 shows the relationship between a seam portion between actuator units and pressure generating portions in an additional area in the arrangement of FIG 19 ,

The operating unit 255a from 19 is divided into three areas P11, P12 and P13 in the lateral direction of the passage unit. The central area P11 in the lateral direction of the passage unit serves as a base area, and the remaining areas P12 and P13 serve as additional areas.

As with the arrangement of 17 In the base region P11, a large number of pressure generating sections A11 are arranged side by side in a matrix in the longitudinal direction of the passage unit and along the other side C of the parallelogram. In an additional area P12, pressure generating sections A12 are juxtaposed in a matrix in the immediate vicinity of an acute-angled corner D of the parallelogram near the operating unit 255b arranged. In the other additional area P13, pressure generating sections A13 are juxtaposed in a matrix in the immediate vicinity of an acute-angled corner D of the parallelogram from the operating unit 255b arranged away.

That's why, as in 20 1 illustrates the pressure generating sections A12 of the additional area P12 of the operating unit 255a and the pressure generating sections A13 of the additional area P13 of the operating unit 255b in a gap portion G between the pressure generating portions A11 of the base portion P11 located in the operating unit 255a and the pressure generating sections A11 of the base area P11 located in the adjacent operation unit 255b is located. Thus, the head main body can 201 Ink can be supplied, which can be injected over the entire longitudinal direction of the passage unit without interruption.

Furthermore, this embodiment can also bring about the same advantages as those of the first embodiment described above. Specifically, because the two operating units 255a and 255b in the longitudinal direction of the passage unit 204 can be arranged even in the case of a long passage unit 204 high accuracy in positioning the actuators 255a and 255b at the passage unit 204 be achieved. Therefore, good ink ejection results can be achieved and the production yield of the ink-jet heads 201 can be significantly increased. In addition, by arranging the piezoelectric sheets 241 to 243 between the common electrodes 234a and 234b and the individual electrodes 235a and 235b the volume of each pressure chamber 210 be easily changed by the piezoelectric effect. Furthermore, the piezoelectric layers can 241 to 243 that contain active layers can be easily prepared because they are continuous flat layers. Because also an operating unit 221 is used with a unimorph structure, wherein the piezoelectric layers 244 and 245 near each pressure chamber 210 are inactive and the piezoelectric layers 241 to 243 from each pressure chamber 210 lying apart, layers containing active layers can change the volume of each pressure chamber 210 be amplified by the transverse piezoelectric effect, and it can be a reduction in the individual electrodes 235a and 235b applied voltage and / or high integration of the pressure chambers 210 to be sought. Furthermore, in the passage unit 204 - because a large number of pressure chambers 210 juxtaposed in a matrix - the many pressure chambers 210 be arranged with a high density within a relatively small size.

In this embodiment are two actuators arranged. It can of course also three or more actuators be arranged. Arranging many actuators can become one lead long inkjet head. One such a long inkjet head is beneficial because with him even bigger paper can be printed at high speed.

21A and 21B illustrate head main body 271 and 272 according to modifications of the second embodiment, wherein four actuator units 261 (in the 21A and 21B they are from right to left with the reference numbers 261a . 261b . 261c respectively. 261d respectively), each as an actuator unit 221 or 255 are constructed in a row on passage units 274 , which near its two ends ink supply openings 273 have, are arranged and bonded thereto. Such an actuating unit 261 as an operating unit 221 or 255 , can be used in common for passage units of different lengths, for example of a relatively short passage unit, as in 11 illustrated, up to a long passage unit, as in 21A illustrated. Thus, such an operating unit can be widely used as a component, whereby the manufacturing cost can be reduced.

In the head main bodies 201 and 271 as in the 11 and 21A illustrated, operating units are arranged on a passage unit in a straight line so that they are aligned in the lateral direction of the passage unit. However, as in a head main body 272 who, for example, in 21B is illustrated, operating units 261a . 261b . 261c and 261d be arranged in a zigzag shape. However, from the viewpoint of the compactness of an ink jet head, the one disclosed in U.S. Pat 11 or 21A illustrated arrangement in which actuating units in a straight line in the longitudinal direction of the passage unit are arranged so that they are aligned regularly in the lateral direction of the passage unit. Especially in the case of the arrangement of 11 or 21A The inkjet head can be kept narrow. Thus, if two or more ink-jet heads are arranged along their width to supply inks of different colors for multi-color printing, they can be arranged within a compact space. This is also advantageous because the occurrence of color shearing in an image can be reduced even if a paper is skewed in printing.

Next, a third embodiment of the present invention will be described. 22 Fig. 10 is a plan view of a head main body of an ink jet head according to this embodiment. In the ink jet head and the ink jet printer according to this embodiment, since the parts except the head main body are similar to those of the above-described first embodiment, their detailed description is omitted here.

Let us turn 22 to. A head main body 301 An ink jet head according to this embodiment has a rectangular shape extending from one direction as viewed from above. The head main body 301 contains a passage unit 304 in which a large number of pressure chambers 310 and a large number of ink ejection openings 308 are formed, as will be described below. On top of the passage unit 304 are four actuators 321 each with the shape of a regular hexagon (in 22 they are from right to left with the reference numbers 321a . 321b . 321c respectively. 321d zigzag in two rows and are at the top of the passage unit 304 bonded. Each actuation unit 321 is arranged so that its opposite parallel sides (top and bottom sides) in the longitudinal direction of the head main body 301 extend. All adjacent actuators 321 are arranged so that their oblique sides are close to each other and have overlapping portions in the lateral direction of the passage unit.

Let us turn 23 to which is a view of the passage unit 304 in one compared to 22 inverted viewing angle (a view from the printing surface side). Four hexagonal ink ejection areas R2 are located in the bottom of the passage unit 304 according to the respective areas where the operation unit th 321 are arranged. A large number of ink ejection openings 308 small diameter are arranged in the surface of each ink ejection area R2. A basic block 302 is on top of the head main body 301 arranged. A pair of ink reservoirs 303 each having a narrow shape in the longitudinal direction of the head main body 301 are in the basic block 302 arranged. An opening 303a is in the top of the base block 302 at one end of each ink reservoir 303 educated. Every opening 303a is connected to a non-illustrated ink tank. As a result, each ink reservoir is 303 always filled with ink.

24 is a sectional view showing the internal structure of the passage unit 304 illustrated. Let us turn 24 to where distribution channels 305 , which act as ink supply sources, in the passage unit 304 are formed. Each distribution channel 305 stands over the corresponding opening 305a placed in the top of the passage unit 304 is formed with an ink reservoir 303 in fluid communication. Every opening 305a is preferably provided with a filter for collecting dust and dirt contained in the ink.

Each distribution channel 305 branches at its opening 305a to a number of pressure chambers 310 To supply ink, as will be described below. If each hexagonal ink ejection area R2, which in 23 is illustrated in 23 vertically divided equally into two areas, it becomes a single distribution channel 305 formed to correspond to one of the two areas. There are eight distribution channels 305 present, and each of them is shaped to give ink to all the pressure chambers 310 which are contained in the corresponding area, distributed and supplied.

The ink ejection opening 308 , which is located in a half area in the lateral direction of the passage unit, is above a distribution channel 305 with one of the ink reservoirs 303 in a couple in fluid communication. The ink ejection opening 308 in the other half area in the lateral direction of the ink jet head is in communication with the other ink reservoir 303 in fluid communication. By arranging the distribution channels 305 , the openings 305a and the ink reservoir 303 Two modes of printing can be realized: (1) a mode in which the ink reservoirs 303 in the pair are applied with ink of the same color to perform a high-resolution single-color printing, and (2) a mode in which the ink reservoirs 303 in the pair are applied with ink of different colors to produce a two-color print with the single head main body 301 perform. This is a widely usable construction.

Let us turn 26 to. Each ink ejection opening 308 is formed as a tapered nozzle. The ink ejection opening 308 is above a pressure chamber 310 with an almost rhombic shape - viewed from above - and an opening 312 in fluid communication with a distribution channel 305 , In this construction, ink is transferred via the ink reservoir 303 to the distribution channel 305 is also routed from the distribution channel 305 over the opening 312 to the pressure chamber 310 directed. By driving an actuating unit 321 As will be described later, beam energy is applied to the ink in the pressure chamber 310 applied to the ink through the ink ejection port 308 to spray in a jet.

25 FIG. 12 illustrates a detailed structure of the area included in FIG 24 is denoted by the reference E. How out 25 can be seen are in an area of the top of the passage unit 304 that corresponds to an ink ejection area R2, a large number of pressure chambers 310 arranged side by side in a matrix. Because the pressure chambers 310 formed on a different plane than the openings 312 , as in 26 illustrates an arrangement is possible in which each opening 312 that with a pressure chamber 310 connected, another pressure chamber 310 overlaps. As a result, a high-density arrangement of the pressure chambers 310 be realized, resulting in a reduction of the head main body 301 and an increase in the resolution of an image to be produced.

26 illustrates a concrete construction of a passage from a distribution channel 305 to an ink ejection port 308 , Let us turn 26 to. The passage unit 304 is laminated from a total of nine layers of material, namely a cavity plate 322 , a base plate 323 , an orifice plate 324 , a feeder plate 325 , Distribution plates 326 . 327 and 328 , a cover plate 329 and a nozzle plate 330 , The above-described actuators 321 are at the top of the passage unit 304 bonded, whereby a head main body 301 arises. The detailed structure of each actuator 321 will be described below.

A rhombic opening is in the cavity plate 322 designed so that a pressure chamber 310 is formed. A tapered ink ejection port 308 is in the nozzle plate 330 trained with a press. Through each of the plates 323 to 329 passing through between the plates 322 and 330 flow holes 351 educated. The pressure chamber 310 stands over the flow holes 351 with the Tin tenausspritzöffnung 308 in fluid communication. An opening 312 is as a slot in the orifice plate 324 educated. One end of the opening 312 is over a flow hole 352 that in the base plate 323 is formed with an end portion of the pressure chamber 310 (opposite to the end portion connected to the ink ejection port 308 connected). The opening 312 is used to properly control the amount of ink that the pressure chamber 310 is to be supplied, and preventing too much or too little ink through the ink ejection opening 308 is injected. A flow hole 353 is in the feed plate 325 educated. The flow hole 353 connects the other end of the opening 312 with the distribution channel 305 ,

Each of the nine plates 322 to 330 that make up the passage unit 304 is made of metal. The pressure chamber 310 , the opening 312 and the flow holes 351 . 352 and 353 The ones described above are formed by selectively etching each metal plate by means of a mask pattern. The nine plates 322 to 330 are arranged in layers and bonded together, positioning them in such a way that the in 26 illustrated passage is formed.

Next, the structure of each operating unit 321 described. Let us turn 27 to. The operating unit 321 contains five piezoelectric layers 341 to 345 with the same thickness of about 15 microns. These piezoelectric layers rule 341 to 345 are formed as continuous flat layers. A single actuator unit 321 is arranged so that it is over many pressure chambers 310 which extends in a single ink ejection area R2 of the head main body 301 are formed. This allows a high-density arrangement of individual electrodes 335a and 335b will be realized. Each of the piezoelectric layers 341 to 345 consists of a lead zirconate titanate (PZT) based ceramic material with ferroelectricity.

Between the first and second piezoelectric layers 341 and 342 - Seen from above - is about 2 microns thick common electrode 334a arranged, which is formed substantially on the entire lower and upper sides of the piezoelectric layers. Furthermore, between the third and the fourth piezoelectric layer 343 and 344 an approximately 2 μm thick common electrode 234b arranged. On top of the first piezoelectric layer 341 is an approximately 1 micron thick single electrode 335a according to each pressure chamber 310 educated. As in 24 Illustrated has the single electrode 335a - viewed from above - a similar shape as the pressure chamber 310 although the single electrode 335a a little smaller than the pressure chamber 310 , The single electrode 335a is arranged so that the middle of each electrode 335a with the middle of the corresponding pressure chamber 310 matches. Furthermore, between the second and the third piezoelectric layer 342 and 343 an approximately 2 μm thick single electrode 335b arranged like the single electrode 335a is shaped. Between the fourth and the fifth piezoelectric layer 344 and 345 and on the bottom of the fifth piezoelectric layer 345 there is no electrode. Each of the electrodes 334a . 334b . 335a and 335b For example, it is made of an Ag-Pd-based metallic material.

The common electrodes 334a and 334b are grounded in a non-illustrated area. Thus, the common electrodes 334a and 334b in a range of any pressure chamber 310 corresponds to the earthing potential. Thus the potential of the individual electrodes 335a and 335b in each pair, that of a pressure chamber 310 which can be controlled independently of another pair, they are connected via a connecting lead, which is used for each pair of individual electrodes 335a and 335b is separate, connected to a suitable drive IC (not shown).

In the head main body 301 are the piezoelectric layers 341 to 345 to polarize in thickness. That is, the operating unit 321 has a so-called unimorph structure, in which the upper (ie of the pressure chamber 310 distant) three piezoelectric layers 341 to 343 Layers are those containing active layers and the lower ones (ie near the pressure chamber 310 located) two piezoelectric layers 344 and 345 are formed as inactive layers.

If in this construction the individual electrodes 335a and 335b are set to a positive or a negative predetermined potential in a pair and, for example, when the polarization is in the same direction as the electric field, the portion (an active layer, ie, a pressure generating portion) contracts in the piezoelectric sheets 341 to 343 which is located between the common and the individual electrodes, perpendicular to the polarization together. Because on the other hand, the inactive piezoelectric layers 344 and 345 are not affected by any electric field, they do not contract in themselves. Thus, along the polarization, a mechanical stress difference arises between the upper piezoelectric layers 341 to 343 and the lower piezoelectric layers 344 and 345 , As a result, the entire piezoelectric layers are 341 to 345 ready to deform into a convex shape towards the inactive side (unimorphic deformation). Because the bottom of the bottom piezoelectric layer 345 at the top of the dividing wall, which houses the pressure chambers 310 separates, is fixed, the piezoelectric layers deform at this time 341 to 345 to a convex shape toward the side of the pressure chamber 310 to the volume of the pressure chamber 310 to downsize. As a result, the pressure of the ink increases, whereby ink through the ink ejection opening 308 is injected. After that, applying the drive voltage to the individual electrodes 335a and 335b is terminated, so turn the piezoelectric layers 341 to 345 back to the original shape, and the pressure chamber 310 also returns to its original volume. Thus, the pressure chamber sucks 310 Ink over the distribution channel 305 in.

For making each actuator 321 First, ceramic green layers are used as piezoelectric layers 341 to 345 should serve, laid in layers and then fired. At this time, as needed, a metallic material acting as single electrodes 335a or a common electrode 334a or 334b should serve, printed on every ceramic green layer to a pattern. After that, a metallic material is used as individual electrodes 335a should serve on the entire top of the first piezoelectric layer 341 plated, and then superfluous portions of the material are removed by laser structuring. Alternatively, a metallic material that acts as individual electrodes 335a should serve, using a mask with openings on sections that correspond to the individual electrodes 335a correspond, deposited.

The operating unit produced in this way 321 is very brittle because it is made of ceramic. In particular, because the corners of the actuator unit 321 Very easy to break, a very careful handling in the manufacture and assembly required to avoid that one corner comes into contact with another component.

However, as in 28A illustrating a plan view of the actuator unit 321 is in the ink jet head according to this embodiment, the actuator unit 321 the profile of a substantially regular hexagon. Each of six straight sections (sides) L1 to L6 included in this profile is connected to an adjacent straight section L of about 120 °. Thanks to this, since none of the six corners (portions of all the adjacent straight portions L which cross each other) θ1 to θ6 have an acute angle, they are difficult to be broken. That is why the operating unit 321 as an expensive precision component does not break so easily in the middle of the manufacturing process. This can help to reduce the manufacturing costs.

The above effect is achieved not only when one or more of the corners θ1 to θ6 are formed at 120 °. When a corner θn is formed at 90 ° or more, the corner θn is difficult to be broken. Thus, to cause one or more of the six corners θ1 to θ6 to be hard to break off, it is sufficient that one or more of the six straight portions L1 to L6 be connected at right angles or at an obtuse angle to an adjacent straight portion L. (The minimum value of the angles θ1 to θ6 at the crossing portions is 90 ° or more). The hexagonal profile can be changed as long as the above condition is met. 28B illustrates an actuator unit 355 as an example, in which the above condition is satisfied.

Furthermore, this embodiment can also provide the same advantages as in the case of the first embodiment described above. More precisely, because the four actuators 321 in the longitudinal direction of the passage unit 304 can be arranged even in the case of a long passage unit 304 high accuracy in positioning the actuators 321 at the passage unit 304 be achieved. Therefore, good ink ejection results can be achieved and the production yield of the ink-jet heads 301 can be significantly increased. By the piezoelectric layers 341 to 343 between the common electrodes 334a and 334b and the individual electrodes 335a and 335b In addition, the volume of each pressure chamber can be arranged 310 be easily changed by the piezoelectric effect. Furthermore, the piezoelectric layers can 341 to 343 that contain active layers can be easily prepared because they are continuous flat layers. Because also an operating unit 321 is provided with a unimorph structure in which the piezoelectric layers 344 and 345 near each pressure chamber 310 are inactive and the piezoelectric layers 341 to 343 from each pressure chamber 310 lying apart, layers containing active layers can change the volume of each pressure chamber 310 be amplified by the transverse piezoelectric effect, and it can be a reduction in the individual electrodes 335a and 335b applied voltage and / or high integration of the pressure chambers 310 to be sought. Furthermore, in the passage unit 304 - because a large number of pressure chambers 310 juxtaposed in a matrix - the many pressure chambers 310 be arranged with a high density within a relatively small size.

In the present invention according to the Claims, the profile of each actuator is not limited to a hexagon. That is, the number of straight sections L need not be six, but may be five, seven, eight or more. In addition, modifications of the profile of each actuator based on the 28 to 30 described. In the modifications described below, the same components as in the third embodiment described above are denoted by the same reference numerals as in the third embodiment, respectively.

29A Figure 11 is a plan view of a head main body in which each actuator unit is formed in a heptagonal shape. 29B FIG. 10 is a plan view of an operating unit included in the head main body of FIG 29A is included. Like from the 29A and 29B As can be seen, in this modification, the components of the head main body 361 with the exception of the operating units 362 (in 29A they are from right to left with the reference numbers 362a . 362b . 362c respectively. 362d referred) as that of the head main body 301 of the third embodiment.

Let us turn 29B to. Each actuation unit 362 has its profile, wherein a corner of a hexagon according to the above-described embodiment has been cut along a straight line. As a result, the number of straight portions L is seven (L8 to L14), and as for the angles of each corner, the angles θ8 to θ12 are about 120 °, and the angles θ13 and θ14 are about 150 °.

30A Fig. 10 is a plan view of a head main body in which each actuator unit is formed in an octagonal shape. 30B FIG. 10 is a plan view of an operating unit included in the head main body of FIG 30A is included. Like from the 30A and 30B As can be seen, in this modification, the components of the head main body 371 with the exception of the operating units 372 (in the 30A they are from right to left by the reference numbers 372a . 372b . 372c respectively. 372d referred) as that of the head main body 301 of the third embodiment.

Let us turn 30B to. Each actuation unit 372 has its profile in which two corners of a hexagon have been cut along straight lines according to the embodiment described above. As a result, the number of straight portions L is eight (L15 to L22), and as for the angles of each corner, the angles θ15, θ16, θ19 and 820 are about 120 °, and the angles θ17, θ18, θ21 and θ22 are about 150 °. In the two modifications described above, the corner is harder to break than in the case of the hexagonal actuator described above 321 because the angle of each corner of each cut portion is 150 °, which is larger than that of the hexagonal actuator described above 321 ,

31A FIG. 15 is a plan view of a head main body in which two joining portions of adjacent straight portions L in the operating unit of the third embodiment described above are formed as rounded portions F. As shown in FIG. 31B FIG. 10 is a plan view of an operating unit included in the head main body of FIG 31A is included. Like from the 31A and 31B As can be seen, in this modification, the components of the head main body 381 with the exception of the operating units 382 (in 31A they are from right to left by the reference numbers 382a . 382b . 382c respectively. 382d referred) as that of the head main body 301 of the second embodiment.

Let us turn 31B to. Each actuation unit 382 has six straight sections L23 to L28. Two connecting portions of adjacent straight sections L (L23 and L28 and L25 and L26) in the operating unit 382 are formed as rounded portions F, where adjacent straight portions L are smoothly connected to each other. Each rounded section F is very difficult to break. Further, in this case, the angle between all the adjacent straight portions L including two straight portions on both sides of each rounded portion F (θ23 to θ27) is larger than 90 ° (about 120 °).

Next, the fourth embodiment of the present invention will be described with reference to FIG 32 described. In the ink jet head and the ink jet printer according to this embodiment, since the parts other than the head main body are similar to those of the above-described first embodiment, their detailed description is omitted here.

A head main body 401 , as in 32 illustrates contains a passage unit 404 wherein a large number of pressure chambers and a large number of ink ejection openings are formed as in the above-described embodiments. Two parallelogram actuators 421 (in 32 are the right and the left by the reference numbers 421a respectively. 421b referred to) are side by side on the top of the passage unit 404 bonded. Each actuation unit 421 is arranged so that its one side B in the longitudinal direction of the head main body 401 extends. The adjacent actuators 421 are arranged to be in the lateral direction of the head main body 401 are aligned with their oblique sides C close to each other. Two operating units 421 partially overlap each other in the lateral direction of the passage unit 404 , An ink supply port 402 is in the top of the passage unit 404 open. The ink supply port 402 is connected to an ink supply source via a non-illustrated passage.

On top of each actuator unit 421 is a FGS 436. bonded to electrical signals to the individual and the common electrodes in the actuator unit 421 to apply. On every FGS 436. is a drive IC 432 which serves as a driver circuit for generating drive signals applied to the individual electrodes in the corresponding actuator unit 421 be created. Every FGS 436. is electrical with a control unit 440 connected, which includes a CPU, a RAM and a ROM. The control unit 440 feeds print data into each drive IC 432 one. Each drive IC 432 generates drive signals for individual electrodes based on the print data.

In each operating unit 421 There are two areas P21 and P22. Of these, the base portion P21 has a parallelogram-like shape, and its sides are parallel to the respective sides of the corresponding operating unit 421 , The width of the base portion P21 is slightly shorter than the side B of the operating unit 421 , and its length measures about ¾ of the side C of the actuator unit 421 , In 32 is the base area P21 in an upper portion of the operating unit 421 arranged. The additional area P22 has a parallelogram-like shape, and its sides are parallel to the respective sides of the corresponding operating unit 421 , The additional area P22 has the same width as the base area P21 and is disposed on the lower side of the base area P21. The additional area P22 is divided into two portions P22a and P22b, each of which has a parallelogram-like shape whose sides are parallel to the respective sides of the operating unit 421 run. The width of the portion P22a measures about 1/5 of the side B of the operating unit 421 , and its length measures about 1/5 of the side C of the actuator unit 421 , In 32 is the portion P22a in the immediate vicinity of the lower left acute-angled portion of the actuator unit 421 , The width of the portion P22b measures about 3/5 of the side B of the operating unit 421 , and its length measures about 1/5 of the side C of the actuator unit 421 , In 32 the sub-area P22b is on the lower side of the base area P21 and on the right-hand side of the sub-area P22a.

In each of the base region P21 and the partial regions P22a and P22b of the additional region P22, a large number of pressure generating sections are juxtaposed in a matrix in the longitudinal direction of the passage unit 404 and arranged along side C of the parallelogram. Pressure chambers and ink passages containing nozzles are in the passage unit 404 formed according to the respective pressure generating sections.

If the two actuators 421a and 421b , which are constructed as described above, in a row in the longitudinal direction of the passage unit 404 be arranged as in 32 illustrates, an area (hatched area G in FIG 32 ) where there are no pressure generating portions near the seam portion between the operating units 421a and 421b educated. When the single pressure generating sections are considered in the base area P11, the number of the pressure generating sections is in the lateral direction of the passage unit 404 smaller in the immediate vicinity of the seam portion than in the portion which does not form the immediate vicinity of the seam portion.

Thus, in this embodiment, utilizing the feature that the subarea P22a of the additional area P22 located on the lower side of the base area P21 is arranged to correspond to the area G where no pressure generating portions are present near the seam portion and in the lateral direction of the passage unit 404 so controls the control unit 440 each driving IC 432 in printing so that pressure generating sections in the base area P21 and in the subarea P22a of the additional area P22 are driven and no pressure generating sections in the subarea P22b of the additional area P22 are driven. This is because - because the pressure generating sections in the actuator unit 421 in an area of substantially the same shape as in the operating unit 221 from 18 are arranged - the number of pressure generating sections in the passage unit 404 in the immediate vicinity of the seam section the same as in the other section. That is, because the pressure generating sections of the partial area P22a of the additional area P22 are arranged to correspond to the gap portion between the pressure generating sections of the base area P21 located in an actuator unit 421a located, and the pressure generating sections of the base portion P21, located in the adjacent actuator unit 421b can correspond, the head main body 401 be equipped with the ability to print without interruption over the entire longitudinal direction of the passage unit without having to provide another actuator unit for ejecting ink through the gap portion. Because, further, the pressure generating section forming area in each operating unit 421 a similar shape as the operating unit 421 , There may hardly be a problem of warping, bending or the like of the operating unit 421 come.

As apparent from the above description, in this embodiment, no ink passages are needed in the portion of the passage unit 404 , which corresponds to the partial area P22b of the additional area P22, to be present.

The Materials of each piezoelectric layer and each electrode, the in the embodiments described above are not limited to those described above. she can against other known materials are exchanged. The in plan view and sectional views illustrated forms each pressure chamber, the Arrangement of the pressure chambers, the number of piezoelectric layers, which contain active layers, the number of inactive layers etc. can the expediency changed accordingly become. Any piezoelectric layer containing active layers can have a different thickness than any inactive layer.

Of Further, in the above-described embodiments, each actuator unit designed so that single and common electrodes on one piezoelectric layer are arranged. But such an operating unit does not always need to be bonded to the passage unit. It can also every other operating unit used when they are the volumes of the respective pressure chambers change separately can. Furthermore, in the embodiments described above Pressure chambers arranged in a matrix. But the pressure chambers can too be arranged in one or more rows. And although in the embodiment described above each inactive layer consists of a piezoelectric layer, the inactive layer can also consist of an insulating layer, which is not a piezoelectric layer.

Claims (8)

Ink jet head comprising: a passage unit ( 204 ), which has a plurality of pressure chambers ( 210 ), each of which has an end connected to a nozzle ( 208 ), and the other end to be connected to an ink supply source, wherein the plurality of pressure chambers ( 210 ) are arranged along a plane so as to be adjacent to each other; and a plurality of actuator units ( 221 ) located on a surface of the passage unit ( 204 ) are attached to change the volume of each of the pressure chambers ( 210 ), each of the operating units ( 221 ) includes a plurality of pressure generating sections (A1, A2) corresponding to pressure chambers (A1, A2) 210 ), each of the actuating units ( 221 ) is formed so that they are above the pressure chambers ( 210 ), the plurality of actuator units ( 221 ) along the longitudinal direction of the passage unit ( 204 ) is arranged so that all adjacent operating units ( 221 ) partially in the lateral direction of the passage unit ( 204 ) overlap; each actuation unit ( 221 ): a base region (P1) in which a large number of pressure generating sections (A1) are formed in a matrix; and an additional area (P2) adjacent to the base area (P1) in the lateral direction of the passage unit (FIG. 204 ) in the pressure generating portion (A2) corresponding to a gap portion (G) between the pressure generating portions (A1) in the base portion (P1) of the actuator unit (Fig. 221 ) and the pressure generating sections (A1) in the base area (P1) of another operating unit ( 221 ) adjacent to the actuator unit ( 221 ), so that the pressure generating sections in the additional area (P2) can compensate for the missing pressure generating sections in the gap section (G). An ink jet head according to claim 1, wherein each of said actuator units ( 221 ) has a substantially tetragonal flat shape and the additional area (B2) near a sharp corner of the actuating unit ( 221 ) is provided. An ink-jet head according to claim 2, wherein each of the actuator units ( 221 ) has a substantially parallelogram-like flat shape, the plurality of actuator units ( 221 ) along the longitudinal direction of the passage unit ( 204 ) being adjacent to each other so that one of opposite sides of each of the operating units ( 221 ) parallel to the longitudinal direction of the passage unit ( 204 ) and the other of the opposite sides obliquely relative to the longitudinal direction of the passage unit (FIG. 204 ), and the additional area (P2) is provided near a sharp corner of the operating unit. An ink-jet head according to any one of claims 1 to 3, wherein no pressure generating portions (A) are provided in an area adjacent to the additional area (P2) in the longitudinal direction of the passage unit (12). 204 ) and adjacent to the base region (P1) in the lateral direction of the passage unit (FIG. 204 ) are provided. An ink-jet head according to claim 1 to 4, wherein lines in which a large number of pressure generating sections (A) are arranged in each of Actuators ( 221 ), and the number of lines having an imaginary straight line perpendicular to the longitudinal direction of the passage unit (FIG. 204 ) in an area where adjacent actuator units ( 221 ) overlap each other, the same as the number of lines crossing the straight line in an area where adjacent operation units (FIGS. 221 ) do not overlap each other. An ink jet head according to any one of claims 1 to 5, wherein two or more of the actuator units ( 221 ) are arranged in a line along the longitudinal direction of the passage unit. Inkjet printer with an inkjet head, such as he in one of the claims 1 to 6 is claimed. An ink jet printer comprising: an ink jet head; a drive circuit for driving the ink-jet head; and a control unit ( 440 ), the ink jet head comprising: a passage unit ( 404 ) having a plurality of pressure chambers, each having one end connected to a nozzle and the other end to be connected to an ink supply source, the plurality of pressure chambers arranged along a plane adjacent to each other be; and a plurality of actuator units ( 421 ) located on a surface of the passage unit ( 404 ) for changing the volume of each of the pressure chambers, each of the actuating units ( 421 ) includes a plurality of pressure generating sections corresponding respectively to pressure chambers, each of said actuator units (15) 421 ) is formed so that they extend over the pressure chambers, the plurality of actuating units ( 421 ) along the longitudinal direction of the passage unit ( 404 ) is arranged so that all adjacent operating units ( 421 ) partially overlap each other in the lateral direction of the passage unit; each of the operating units ( 421 ) comprises: a base region (P21) in which a large number of pressure generating sections are formed in a matrix; and an additional area (P22) adjacent to the base area in the lateral direction of the passage unit in which pressure generating sections are formed, wherein the control unit (16) 440 ) the driver circuit ( 432 ) for driving only pressure chambers in the additional area (P22) which is adjacent to a void portion (G) between the pressure generating sections in the base area (P21) of the actuator unit (P21) 421 ) and the pressure generating sections in the base area (P21) of another operating unit ( 421 ) adjacent to the actuator unit ( 421 ) controls when the ink jet head is operated, so that the pressure generating sections in the additional area (P22) can compensate for the missing pressure generating sections in the gap area (G).