JP6089061B2 - Inkjet recording head and inkjet recording apparatus - Google Patents

Description

  Embodiments described herein relate generally to an ink jet recording head and an ink jet recording apparatus.

  In an ink jet recording apparatus used as an image recording apparatus (image forming apparatus) such as a printer, a facsimile machine, a copying apparatus, or a plotter, an ink jet recording head that is a droplet discharge head including a microactuator is used. An ink jet recording head includes a nozzle that ejects ink droplets, a liquid chamber (also referred to as a pressure chamber, a pressure chamber, a pressurized liquid chamber, an ink flow path, and a discharge chamber) that communicates with the nozzle, Pressure generating means (actuator means) for pressurizing the ink in the chamber. Then, by driving the actuator means, the ink in the liquid chamber is pressurized and ink droplets are ejected from the nozzles.

  Conventional ink jet recording heads are roughly classified into piezoelectric type and bubble type in terms of the type of actuator means. A piezoelectric ink jet head ejects ink droplets by deforming and displacing a diaphragm that forms a wall surface of a liquid chamber using a piezoelectric element. A bubble-type inkjet head uses a heating resistor disposed in a liquid chamber to generate bubbles by ink film boiling and eject ink droplets.

  Among the ink jet recording heads as described above, the piezoelectric type has the advantage that there is no restriction on the type of ink used because the piezoelectric element does not directly contact the ink and the heat generation of the piezoelectric element can be ignored. On the other hand, there are significant mechanical and thermal technical problems such as high heat treatment (PZT firing) of the piezoelectric elements and division and alignment of the individual piezoelectric elements when using the laminated piezoelectric elements. Therefore, the cost increases due to complicated processes and apparatuses.

  Also, the bubble type has the advantage that the head can be highly integrated and miniaturized easily because the heater can be made very small by application of semiconductor technology. On the other hand, the heater surface temperature increases to 400 to 450 ° C. in order to generate bubbles. For this reason, since an extremely high heat is applied to the ink, the ink composition changes, and kogation occurs at the ink contact portion of the heater. For this reason, the selection of the ink dye is important, it is difficult to use the pigment ink, and there is a limit to the improvement of the image quality of the color image. In addition, defects such as bubble generation due to deterioration of the heater due to kogation or failure of the heater protective film due to high heat and breakage of the heater due to cracks are likely to occur.

  Therefore, a so-called piezoelectric MEMS type ink jet recording head in which a semiconductor process technology is applied to the piezoelectric type has attracted attention.

JP2013-75510A

  In a piezoelectric MEMS ink jet recording head, a high-density integrated head is manufactured by integrating a large number of cells that are ink ejecting units (units including a pressure chamber, an actuator, a common electrode, and individual electrodes). In this case, normally, an assembly of individual cells is arranged on the inner side of the substrate, and a connection electrode for connecting to a driving element (actuator) is provided on the outer side. Then, individual cells and connection electrodes are connected by lead wires. One of the examination subjects in this case is how to arrange the lead wiring.

  As an example of the ink jet recording head, for example, there is an apparatus having a configuration in which a circular cell is used and lead-out wirings from a plurality of inner cells are formed between adjacent cells arranged on the outer side of a substrate. In this case, the lead-out wiring is formed on the wall portion between adjacent cells. However, this structure has a problem that when an integrated head in which a large number of cells are integrated at a high density is produced, the area of the lead-out wiring increases, and consequently the area of the integrated head increases. This has the same problem even when, for example, rectangular or rhombus cells are used.

  In view of such circumstances, the embodiments provide a piezoelectric MEMS type (piezoelectric thin film type) inkjet recording head, and an inkjet recording head and an inkjet recording apparatus suitable for a high-density integrated head with a small area. And

One ink jet recording head of the embodiment has a collective head. The collective head is formed by arranging a plurality of cells of the ink ejection unit. The cell of the ink ejection unit includes a vibration plate, a piezoelectric drive element, a nozzle, and a pressure generation chamber. The diaphragm is formed on the silicon substrate. The piezoelectric driving element includes a lower electrode, a piezoelectric film, and an upper electrode on the diaphragm. The nozzle is formed on the diaphragm. The pressure generating chamber is formed in the silicon substrate adjacent to the diaphragm. The collective head is formed so that an outer shape of the piezoelectric driving element is smaller than an outer shape of the pressure generating chamber, and an extraction wiring connected to either the upper electrode or the lower electrode is connected to the other of the cells. It is formed over the diaphragm above the pressure generating chamber.

FIG. 1 is a longitudinal sectional view showing a schematic configuration of the entire inkjet printer according to the first embodiment. FIG. 2 is a top view of the ink jet head according to the first embodiment. FIG. 3 is a partially enlarged view of part A in FIG. 4 is a cross-sectional view taken along line F4-F4 of FIG. 5 is a cross-sectional view taken along line F5-F5 of FIG. FIG. 6 is a longitudinal sectional view of a main part showing a state in which a silicon substrate is thermally oxidized and silicon oxide films are formed on the front surface and the back surface in the ink jet head manufacturing method of the first embodiment. FIG. 7 is a longitudinal sectional view of a main part showing a state where a piezoelectric element having a lower electrode, a piezoelectric film, and an upper electrode is formed on the silicon oxide film of FIG. FIG. 8 is a longitudinal cross-sectional view of the main part showing a state in which the diaphragm of FIG. 7 is patterned to form the lower electrode and the extraction electrode at the same time. FIG. 9 is a longitudinal cross-sectional view of a main part showing a state in which an insulating film is formed so as to cover the silicon oxide film, the lower electrode, the extraction electrode, and the upper electrode. FIG. 10 is a longitudinal sectional view of a main part showing a state in which the common wiring is formed and the common wiring is patterned by photolithography and reactive ion etching. FIG. 11 is a longitudinal sectional view of a main part showing a state in which a pressure generation chamber is formed from the back surface side facing the piezoelectric element of the silicon substrate by back surface photolithography and D-RIE. FIG. 12 is a partially enlarged plan view of the ink jet head according to the second embodiment. FIG. 13 is a cross-sectional view taken along line F13-F13 in FIG. 14 is a cross-sectional view taken along line F14-F14 in FIG. FIG. 15 is a top view of the ink jet head according to the third embodiment. 16 is a cross-sectional view taken along line F16-F16 in FIG. 17 is a cross-sectional view taken along line F17-F17 in FIG. FIG. 18 is a longitudinal sectional view of the main part showing a state where ring-shaped grooves are formed on the wafer surface of FIG. FIG. 19 is a longitudinal cross-sectional view of a main part showing a state in which a silicon substrate is oxidized by thermal oxidation to form a silicon oxide film and a silicon oxide film side wall at the same time. FIG. 20 is a longitudinal sectional view of a main part showing a state in which a piezoelectric element having a lower electrode, a piezoelectric film, and an upper electrode is formed on a silicon oxide film. FIG. 21 is a vertical cross-sectional view of a main part showing a state in which an insulating film is formed so as to cover the silicon oxide film, a part of the lower electrode, the extraction electrode, and the upper electrode. FIG. 22 is a longitudinal cross-sectional view of a main part showing a state in which common wiring is formed and the common wiring is patterned. FIG. 23 is a longitudinal sectional view of a main part showing a state where a nozzle opening is formed by patterning an oxide film. FIG. 24 is a longitudinal sectional view of a main part showing a state where a pressure generation chamber is formed from the back surface side of the silicon substrate by back surface photolithography and D-RIE. FIG. 25 is a top view of the ink jet head according to the fourth embodiment.

Hereinafter, embodiments will be described with reference to the drawings. 1 to 11 show a first embodiment.
FIG. 1 is a schematic diagram illustrating an inkjet printer 100 (hereinafter simply referred to as a printer 100) according to an embodiment.
The printer 100 has a housing 101. A holding roller 2 is provided in the housing 101 so as to be rotatable in the direction of the arrow. Below the holding roller 2, a paper feed cassette 3 that stores paper P is provided. A paper discharge tray 102 is provided at the upper end of the housing 101.

  The paper P taken out from the paper feed cassette 3 by the pickup roller 3a is transported to the holding roller 2 by two pairs of transport rollers 4a and 4b. The sheet P conveyed to the holding roller 2 is pressed against the surface of the holding roller 2 by the pressing roller 5a, is charged by the charging roller 5b, and is electrostatically attracted to the surface of the holding roller 2. The sheet P adsorbed on the surface of the holding roller 2 is further conveyed by the rotation of the holding roller 2. The holding roller 2 is formed of cylindrical aluminum and is grounded.

  The sheet P conveyed by the rotation of the holding roller 2 passes through a plurality of colors (here, four colors are shown as an example) ink jet recording heads (hereinafter referred to as ink jet heads) 6C, 6M, 6Y, 6K. Is done. The ink jet heads 6C, 6M, 6Y, and 6K for the respective colors discharge the inks of cyan, magenta, yellow, and black, respectively, and form the images of the respective colors on the paper P. Since the inkjet heads 6C, 6M, 6Y, and 6K have the same structure, they may be simply referred to as the inkjet head 6 in the following description.

  The paper P on which the color image is formed by passing through the ink jet heads 6C, 6M, 6Y, and 6K for each color is discharged by the charge removal charger 7a and peeled from the surface of the holding roller 2 by the peeling claw 7b. The paper P peeled off from the holding roller 2 is discharged to the paper discharge tray 102 through the three pairs of paper discharge rollers 8a, 8b, and 8c.

  Alternatively, when images are formed on both sides of the paper P, the paper P peeled off from the holding roller 2 is sent to the reversing unit 9 via the paper discharge roller pair 8a. The reversing unit 9 reverses the paper P by reversing the transport direction of the paper P and feeding it to the transport roller pair 4b. The conveyance roller pair 4 b re-feeds the reversed paper P to the holding roller 2. The holding roller 2 after the paper P is peeled off is cleaned by the cleaning roller 103.

  FIG. 2 is a top view of the inkjet head 6 according to the first embodiment. The inkjet head 6 is a piezoelectric MEMS type head. As shown in FIG. 2, the inkjet head 6 of the present embodiment includes a plurality of individual cells (ink ejection units) 70, which will be described later, having a rectangular (rectangular) planar shape when viewed from the upper surface. Arranged in a shape. Here, for example, the paper feed direction of the printer 100 is the X direction, and the direction orthogonal to the paper feed direction is the Y direction. A plurality of individual cells 70 are arranged on the silicon substrate 10 in a total of 6 rows of 3 rows on each side in the X direction and 20 stages with a pitch shift in the Y direction. Is formed.

  The external electrodes 42 for individual driving of the individual cells 70 are arranged in parallel on the left and right ends of the silicon substrate 10 in FIG. Here, a total of 60 external electrodes 42 are formed at the left end of the silicon substrate 10 in FIG. Similarly, a total of 60 external electrodes 42 are formed at the right end of the silicon substrate 10 in FIG. 2 in two rows in the X direction, each 30 in the Y direction. As a result, a total of 120 external electrodes 42 are formed on the left and right ends of the silicon substrate 10 in FIG.

  A total of four common electrodes 63 are formed at the four corners of the silicon substrate 10. A common wiring 62 a extending in the Y direction is formed at the central portion in the X direction of the silicon substrate 10. The upper and lower ends of the common wiring 62a in FIG. 2 are respectively connected to the common wiring 62b in the X direction. The common electrodes 63 on the upper left and right sides of the silicon substrate 10 are connected to both ends of the upper X-direction common wiring 62b, respectively. Similarly, the common electrodes 63 on the left and right sides of the lower end of the recon substrate 10 are respectively connected to both ends of the lower X-direction common wiring 62b.

  3 shows an enlarged view of a part A in FIG. 2, FIG. 4 shows a cross-sectional view taken along line F4-F4 in FIG. 3, and FIG. 5 shows a cross-sectional view taken along line F5-F5 in FIG. 2 and 3 do not show an insulating film 51 to be described later for easy understanding of the display.

  As shown in FIGS. 4 and 5, the individual cell 70 of the inkjet head 6 includes a vibration plate 21, a lower electrode 31, a piezoelectric film 32, an upper electrode 33, an insulating film 51, a nozzle 53, and a pressure generation chamber. Twelve. The diaphragm 21 is made of a silicon oxide film formed on the main surface of the silicon substrate 10. The lower electrode 31 is formed on the diaphragm 21. The piezoelectric film 32 is formed on the lower electrode 31. The upper electrode 33 is formed on the piezoelectric film 32. The lower electrode 31, the piezoelectric film 32, and the upper electrode 33 on the vibration plate 21 form a piezoelectric element 30 that is a piezoelectric driving element.

  The insulating film 51 is formed so as to cover the diaphragm 21, a part of the lower electrode 31, and the upper electrode 33. The nozzle 53 is formed at the center of the diaphragm 21. The pressure generating chamber 12 is formed in the silicon substrate 10 in a state of being in contact with the diaphragm 21 and the side wall 11 of the silicon substrate 10.

  Further, each individual cell 70 is connected to a lead wiring 41 for individual driving and a common wiring 61 connected to the plurality of individual cells 70. One end portion (left end portion) of the lead wiring 41 for individual driving of each individual cell 70 arranged in the left region of the silicon substrate 10 in FIG. 2 is an external electrode 42 arranged on the left end side of the silicon substrate 10. Are connected to each. The other end of the lead wire 41 is connected to the lower electrode 31 of each individual cell 70 as shown in FIG.

  In addition, the lead wiring 41 for individual driving of each individual cell 70 arranged in the left region in FIG. 2 is arranged as follows. As shown in FIG. 3, the lead wiring 41a connected to the lower electrode 31a of the individual cell 70a (right end in FIG. 3) in the center of the silicon substrate 10 is connected to the pressure generating chamber of the second row of individual cells 70b from the inside. 12 passes over the diaphragm 21 (excluding the uppermost cell), and further passes over the diaphragm 21 above the pressure generation chamber 12 of the outer individual cell 70c and is connected to the external electrode 42a. Has been.

  In addition, the lead wiring 41b connected to the lower electrode 31b of the individual cell 70b in the second row from the inside similarly passes over the diaphragm 21 on the pressure generation chamber 12 of the outer individual cell 70c, and passes through the external electrode 42b. It is connected to the. Similarly, the lead-out wiring 41c connected to the lower electrode 31c of the individual cell 70c in the third column from the inside (left end portion in FIG. 3) is connected to the external electrode 42c.

  Further, dummy wirings 44 are formed on the diaphragm 21 of the inner individual cell 70a and the individual cell 70b in the second column from the inner side. Here, in the inner individual cell 70a, two dummy wirings 44 are arranged in parallel above and below the lower electrode 31a in FIG. In the individual cell 70b in the second column from the inside, one dummy wiring 44 is arranged in parallel to the lead wiring 41a passing below the lower electrode 31b above the lower electrode 31b.

  As a result, the driving conditions are adjusted so as to be equivalent to the case where the lead wires 41a and 41b of the other individual cells 70a and 70b are formed above and below the lower electrode 31c as in the individual cells 70c in the third column from the inside. ing.

  Similarly, one end portion (right end portion) of the lead wiring 41 for individual driving of each individual cell 70 arranged in the right region in FIG. 2 of the silicon substrate 10 is arranged on the right end side of the silicon substrate 10. Each is connected to the external electrode 42. The other end of the lead wiring 41 is connected to the lower electrode 31 of each individual cell 70. Further, the individual driving lead wires 41 of the individual cells 70 arranged in the right region in FIG. 2 are also drawn in the same manner as the individual driving lead wires 41 of the individual cells 70 arranged in the left region. The wiring 41 is arranged in a state formed over the diaphragm 21 on the pressure generation chamber 12 of the other individual cell 70.

  On the other hand, the common wiring 61c connected to the upper electrode 33c of the outer individual cell 70c is connected to the upper electrode 33b of the individual cell 70b in the second column from the inner side. Further, the upper electrode 33b is connected to the upper electrode 33a of the individual cell 70a in the center via the common wiring 61b. Furthermore, the upper electrode 33a is connected to the common wiring 62a via the common wiring 61a.

  As the silicon substrate 10, for example, a plate material (sheet) having a thickness of about 100 to 600 μm is used. The thickness of the silicon substrate 10 is desirably about 200 to 500 μm. This is because the arrangement density of the pressure generating chambers 12 can be increased while maintaining the ease of handling when the silicon substrate 10 is manufactured.

  The diaphragm 21 is formed of, for example, a silicon oxide film (silicon dioxide) having a thickness of 1 to 5 μm, which is created by thermal oxidation or CVD. The silicon oxide film is desirably amorphous from the viewpoint that uniform deformation can be realized. It is also desirable from the viewpoint of easy production of a film having a stable composition and characteristics. Furthermore, it is desirable from the viewpoint of good consistency with conventional semiconductor processes.

As the piezoelectric film 32, a piezoelectric material having a large electrostriction constant such as lead zirconate titanate (Pb (Zr, Ti) O ₃ , PZT) is suitable. When PZT is used for the piezoelectric film 32, noble metals such as Pt, Au, Ir, and conductive oxides such as SrRuO ₃ are suitable for the lower electrode 31 and the upper electrode 33. In addition, as the piezoelectric film 32, a piezoelectric material suitable for a silicon process such as AlN or ZrO ₂ can be used. In this case, general electrode materials such as Al and Cu and wiring materials can be used as the lower electrode 31 and the upper electrode 33.

  In accordance with a recording signal from an external drive circuit (not shown), a drive voltage is applied between the lower electrode 31 and the upper electrode 33 to contract the piezoelectric film 32. Thereby, the diaphragm 21 is bent and deformed into a concave shape, and the volume of the pressure generating chamber 12 is increased. At this time, ink flows into the pressure generation chamber 12 from an ink supply path (not shown). Next, when the drive voltage is removed, the bending deformation of the diaphragm 21 is restored, and the volume of the pressure generating chamber 12 is reduced. As a result, the pressure of the ink in the pressure generating chamber 12 increases, and ink droplets are ejected from the nozzle 53.

  6-11 is a figure which shows the manufacturing method of the inkjet head 6 of this embodiment. Hereinafter, a process of forming the diaphragm 21 and the piezoelectric element 30 on the silicon single crystal silicon substrate 10 will be described with reference to FIGS.

  As shown in FIG. 6, first, the silicon substrate 10 is thermally oxidized to form silicon oxide films 20a and 20b on the front and back surfaces. In the present embodiment, the silicon oxide films 20a and 20b are formed by thermal oxidation of the silicon substrate 10. However, plasma CVD methods other than thermal oxidation methods, CVD methods using TEOS as a raw material, and the like can also be used. .

  Next, as shown in FIG. 7, a piezoelectric element 30 is formed on the silicon oxide film 20a on the surface side of the silicon substrate 10 by sputtering. The piezoelectric element 30 includes a lower electrode 31 made of Ti / Pt, a piezoelectric film 32 made of PZT, and an upper electrode 33 made of Pt. Then, the upper electrode 33 and the piezoelectric film 32 are patterned by photolithography and reactive ion etching.

  Next, as shown in FIG. 8, the lower electrode 31 is patterned by photolithography and reactive ion etching. At this time, lead wires 41 for driving individual cells are formed simultaneously.

  Next, as shown in FIG. 9, an insulating film 51 is formed so as to cover the silicon oxide film 20 a, the lower electrode 31, the extraction wiring 41, and the upper electrode 33 on the surface side. The insulating film 51 is made of a silicon oxide film by a plasma CVD method or a thermal CVD method. Further, the via hole 52 is formed by patterning the insulating film 51 by photolithography and reactive ion etching.

  Next, as shown in FIG. 10, a common wiring 61 made of Al is formed by sputtering, and the common wiring 61 is patterned by photolithography and reactive ion etching. After that, although not shown, the nozzle 53 is formed by patterning the insulating film 51 and the silicon oxide film 20a on the surface side by photolithography and reactive ion etching.

Next, as shown in FIG. 11, the pressure generation chamber 12 is formed from the back side facing the piezoelectric element 30 of the silicon substrate 10 by back side photolithography and D-RIE. At this time, the silicon oxide film 20 a on the surface side that remains without being etched becomes the vibration plate 21.
In the series of film formation and etching described above, a large number of chips are simultaneously formed on a single wafer, and divided into a plurality of chips after the process is completed.
The inkjet head 6 of this embodiment can be manufactured by the above manufacturing method.

(Action / Effect)
In the inkjet head 6 of the present embodiment, the lead wiring 41 connected to the lower electrode 31 that drives the individual cell 70 is formed over the diaphragm 21 on the pressure generation chamber 12 of the other individual cell 70. ing. Specifically, as described above, in FIG. 3, the lead wire 41a connected to the lower electrode 31a of the individual cell 70a (right end portion in FIG. 3) at the center of the silicon substrate 10 is in the second column from the inside. The individual cells 70b are arranged so as to pass over the diaphragm 21 above the pressure generation chamber 12 (except for the uppermost cell). That is, it is arranged on the diaphragm 21 on the pressure generation chamber 12 of the individual cell 70b in the second row from the inside. The lead wiring 41a is further disposed so as to pass over the diaphragm 21 on the pressure generation chamber 12 of the outer individual cell 70c, and is connected to the external electrode 42a. Similarly, the lead-out wiring 41b connected to the lower electrode 31b of the individual cell 70b in the second row from the inside passes over the diaphragm 21 on the pressure generation chamber 12 of the outer individual cell 70c and passes to the external electrode 42b. It is connected. By providing the above-described configuration, the lead-out wiring 41 and the common wiring are formed in comparison with the case where the lead-out wiring from a plurality of inner cells is formed on the wall portion between the pressure generating chambers of adjacent cells arranged outside the substrate. The area required for the wiring 61 is greatly reduced, and the area of the inkjet head 6 can be greatly reduced. Therefore, the inkjet head 6 suitable for a high-density integrated head with a small area can be provided.

  Furthermore, in the present embodiment, two dummy wirings 44 are arranged in parallel on the upper and lower sides of the lower electrode 31a in FIG. 3 in the inner individual cell 70a. In the individual cell 70b in the second column from the inside, one dummy wiring 44 is arranged in parallel to the lead wiring 41a passing below the lower electrode 31b above the lower electrode 31b. As a result, the driving conditions are adjusted so as to be equivalent to the case where the lead wires 41a and 41b of the other individual cells 70a and 70b are formed above and below the lower electrode 31c as in the individual cells 70c in the third column from the inside. ing. For this reason, it is possible to prevent variations in the ink ejection state from each individual cell 70 and improve the print quality.

(Second Embodiment)
12 to 14 show a second embodiment. 12 is an enlarged top view of the inkjet head 110 of the present embodiment, FIG. 13 is a cross-sectional view taken along line F13-F13 in FIG. 12, and FIG. 14 is a cross-sectional view taken along line F14-F14 in FIG.

  In the first embodiment, an example in which the lower electrode 31 of the inkjet head 6 is connected to the individual electrode and the upper electrode 33 is connected to the common electrode has been shown. However, in the present embodiment, these are connected in reverse, and the lower electrode is connected. 31 is connected to a common electrode, and the upper electrode 33 is connected to an individual electrode.

  Here, the lead wiring 41 for individual driving of each individual cell 70 is arranged as follows. As shown in FIG. 12, the lead wire 41a2 connected to the upper electrode 33a of the individual cell 70a (right end in FIG. 12) at the center of the silicon substrate 10 is connected to the diaphragm 21 of the individual cell 70b in the second row from the inside. It passes above (except for the uppermost cell), passes over the diaphragm 21 of the outer individual cell 70c, and is connected to the external electrode 42a2.

  Similarly, the lead wiring 41b2 connected to the upper electrode 33b of the individual cell 70b in the second column from the inner side passes over the diaphragm 21 of the outer individual cell 70c and is connected to the outer electrode 42b2. Similarly, the lead wiring 41c2 connected to the upper electrode 33c of the individual cell 70c in the third column (the left end in FIG. 12) from the inside is connected to the external electrode 42c2.

  Further, dummy wirings 44 are formed on the diaphragm 21 of the inner individual cell 70a and the individual cell 70b in the second column from the inner side. Here, in the inner individual cell 70a, two dummy wirings 44 are arranged in parallel above and below the lower electrode 31a in FIG. In the individual cell 70b in the second column from the inside, a single dummy wiring 44 is arranged above the lower electrode 31b in parallel with the lead wiring 41a2 passing below the lower electrode 31b.

  As a result, the driving conditions are adjusted to be equivalent to the case where the lead wires 41a2 and 41b2 of the other individual cells 70a and 70b are formed above and below the lower electrode 31c as in the individual cells 70c in the third column from the inside. ing.

  On the other hand, the common wiring 61c2 connected to the lower electrode 31c of the outer individual cell 70c is connected to the lower electrode 31b of the individual cell 70b in the second column from the inner side. Further, the lower electrode 31b is connected to the lower electrode 31a of the individual cell 70a in the center via the common wiring 61b2. Further, the lower electrode 31a is connected to the common wiring 62a through the common wiring 61a2. Since the other configuration is the same as that of the first embodiment, the description thereof is omitted here.

  In the inkjet head 110 according to the present embodiment, the lead wiring 41 connected to the upper electrode 33 that drives the individual cell 70 is formed over the diaphragm 21 of the other individual cell 70. Specifically, as described above, in FIG. 12, the lead-out wiring 41a2 connected to the upper electrode 33a of the individual cell 70a (right end in FIG. 12) at the center of the silicon substrate 10 is in the second column from the inside. Passes through the diaphragm 21 of the individual cell 70b (except for the uppermost cell), passes through the diaphragm 21 of the outer individual cell 70c, and is connected to the external electrode 42a2. Similarly, the lead wiring 41b2 connected to the upper electrode 33b of the individual cell 70b in the second column from the inside passes through the diaphragm 21 of the outer individual cell 70c and is connected to the external electrode 42b2. With the above configuration, the area required for the lead-out wiring 41 and the common wiring 61 can be greatly reduced, and the area of the inkjet head 110 can be greatly reduced. Therefore, the inkjet head 110 suitable for a high-density integrated head with a small area can be provided.

  Further, in the present embodiment, two dummy wirings 44 are arranged in parallel on the upper and lower sides of the lower electrode 31a in FIG. 12 in the inner individual cell 70a. In the individual cell 70b in the second column from the inside, a single dummy wiring 44 is arranged above the lower electrode 31b in parallel with the lead wiring 41a2 passing below the lower electrode 31b. As a result, the driving conditions are adjusted to be equivalent to the case where the lead wires 41a2 and 41b2 of the other individual cells 70a and 70b are formed above and below the lower electrode 31c as in the individual cells 70c in the third column from the inside. ing. For this reason, it is possible to prevent variations in the ink ejection state from each individual cell 70 and improve the print quality.

(Third embodiment)
15 to 24 show a third embodiment. FIG. 15 is a top view of the inkjet head 200 according to the third embodiment. 16 is a cross-sectional view taken along line F16-F16 in FIG. 15, and FIG. 17 is a cross-sectional view taken along line F17-F17 in FIG.

  The ink jet head 200 of this embodiment is a piezoelectric MEMS ink jet head. In the ink jet head 200 of this embodiment, an oxide film side wall 23 is formed on the upper side of the side wall 11 of the silicon substrate 10 in contact with the pressure generating chamber 12 as shown in FIG. Further, as shown in FIG. 17, the pressure generating chamber 12 is different from the first embodiment in that a partition wall 13 that connects between the side walls 11 on both sides of the silicon substrate 10 is formed. Except for this point, the second embodiment is basically the same as the first embodiment, and therefore, the description overlapping with the first embodiment is omitted.

  In this embodiment, as shown in FIGS. 16 and 17, an oxide film side wall 23 is formed on the upper side of the side wall 11 of the silicon substrate 10. When the rectangular pressure generation chamber 12 is formed by etching the silicon substrate 10 from the back surface by the D-RIE process, the etching rate ratio between the silicon substrate 10, the silicon oxide film 20a, and the oxide film side wall 23 can be increased (for example, 100: 1 or more when Bosch method is used for etching). Therefore, there is an advantage that the size of the diaphragm 21 can be controlled very accurately.

  In the present embodiment, as shown in FIG. 17, the partition wall 13 is formed in the rectangular pressure generation chamber 12 at a position corresponding to the nozzle 53. The partition wall 13 serves to reinforce the communication between the side walls 11 on both sides of the pressure generating chamber 12.

  For example, two openings (first opening 14 a and second opening 14 b) are formed on both sides of the partition wall 13 on the back surface side of the silicon substrate 10. By using one first opening portion 14a as an ink supply port and the other second opening portion 14b as an ink discharge port, an ink circulation type inkjet head can be realized.

  Ink injected from the first opening 14a, which is an ink supply port, rises in the pressure generation chamber 12a. Subsequently, the gas flows through the periphery of the nozzle 53 along the diaphragm 31 and flows into the pressure generating chamber 12b side. Furthermore, the pressure generation chamber 12b is lowered and discharged from the second opening 14b which is an ink discharge port. Since the ink is circulated through the periphery of the nozzle 53 in this way, even when bubbles are generated in the vicinity of the nozzle 53, the ink can be quickly discharged.

  18-24 is a figure which shows the manufacturing method of the inkjet head 200 of this embodiment. Hereinafter, a process of forming the vibration plate 21 and the piezoelectric element 30 on the silicon substrate 10 will be described with reference to FIGS.

  As shown in FIG. 18, a rectangular annular groove 24 is first formed on the wafer surface of the silicon substrate 10. Next, as shown in FIG. 19, the silicon substrate 10 is oxidized by thermal oxidation to form silicon oxide films 20 a and 20 b on both the front and back surfaces of the silicon substrate 10 and the silicon oxide film side walls 23 at the same time. At this time, the inside of the groove 24 can be filled with the oxide film by adjusting the width of the groove 24 and the oxide film thickness. Specifically, when the thickness of the oxide film 20a is 1, it is desirable that the width of the groove 24 is about 1.12 and the thickness of the oxidized oxide side wall 23 is about 2 or more.

  In this embodiment, the oxide films 20a and 20b and the silicon oxide side wall 23 are formed by thermal oxidation of the silicon substrate. However, a plasma CVD method other than the thermal oxidation method, a CVD method using TEOS as a raw material, or the like is also used. It is possible.

  Next, as shown in FIG. 20, a piezoelectric element 30 is formed on the silicon oxide film 20a on the surface side of the silicon substrate 10 by sputtering. The piezoelectric element 30 includes a lower electrode 31 made of Ti / Pt, a piezoelectric film 32 made of PZT, and an upper electrode 33 made of Pt. Then, the upper electrode 33 and the piezoelectric film 32 are patterned by photolithography and reactive ion etching. Further, the lower electrode 31 is patterned by photolithography and reactive ion etching. At this time, the lead wiring 41 for driving the individual cell connected to the lower electrode 31 is also formed at the same time.

  Next, as shown in FIG. 21, a silicon oxide film is formed by plasma CVD or thermal CVD so as to cover the silicon oxide film 20a, a part of the lower electrode 31, the lead wiring 41, and the upper electrode 33. An insulating film 51 made of is formed. Further, the via hole 52 is formed by patterning the insulating film 51 by photolithography and reactive ion etching.

Next, as shown in FIG. 22, a common wiring 61 made of Al is formed on the insulating film 51 by sputtering, and the common wiring 61 is patterned by photolithography and reactive ion etching.
Subsequently, as shown in FIG. 23, the nozzle 53 is formed by patterning the oxide film 20a by photolithography and reactive ion etching.

  Next, as shown in FIG. 24, pressure generation chambers 12a and 12b are formed from the back surface side of the silicon substrate 10 facing the piezoelectric element 30 by back surface photolithography and D-RIE. In the present embodiment, the resist pattern is formed in a planar shape composed of two rectangles that are slightly smaller than the rectangular shape of the oxide film side wall 23. In the initial stage of D-RIE, etching and side surface passivation are repeated to form two pressure generating chambers 12a and 12b having vertical outer peripheral side walls. Next, after the etching tip reaches the depth of the oxide film sidewall 23, the etching is performed under the condition that the sidewall passivation is weakened and the outer diameter gradually increases. Thus, the oxide film side wall 23 and the oxide film 20a are exposed, and at the same time, the partition wall 13 is thinned from both sides, and the pressure generating chambers 12a and 12b divided into two chambers are combined at the upper portion. At this time, the oxide film 20 a remaining without being etched becomes the vibration plate 21. Thus, an ink flow path that flows from one pressure generation chamber 12a to the other pressure generation chamber 12b can be formed in the pressure generation chamber 12.

In the series of film formation and etching described above, a large number of chips are simultaneously formed on a single wafer, and divided into a plurality of chips after the process is completed.
The inkjet head 200 of this embodiment can be manufactured by the above manufacturing method.

  As described above, according to the present embodiment, it is possible to provide an ink jet recording head in which the area required for the lead-out wiring and the common wiring is greatly reduced, ink circulation is possible, and the area is greatly reduced.

(Fourth embodiment)
FIG. 25 shows a fourth embodiment. FIG. 25 is a top view of the inkjet head 300 according to the fourth embodiment. In the first embodiment, an example in which the planar shape of the pressure generating chamber 12 is rectangular has been described. However, the inkjet head 300 according to the present embodiment has the first shape in that the planar shape of the pressure generating chamber 12 is circular. It is different from the embodiment. Except for this point, the second embodiment is basically the same as the first embodiment, and therefore, the description overlapping with the first embodiment is omitted.

  The ink jet head 300 of this embodiment is a piezoelectric MEMS type ink jet recording head. The ink jet head 300 according to this embodiment includes a pressure generation chamber 12 having a circular plane shape. Further, a circular lower electrode 31 and an upper electrode 33 are provided in accordance with the shape of the pressure generating chamber 12. Except for this point, the second embodiment is basically the same as the first embodiment.

  The embodiment has been described above with reference to specific examples. The above embodiment is merely given as an example and does not limit the present invention. In the description of the embodiment, the description of the ink jet recording head and its manufacturing method, etc., which are not directly necessary for the description of the present invention is omitted, but the ink jet recording head and the manufacturing thereof are required. Elements related to the method and the like can be appropriately selected and used.

  In addition, all inkjet recording heads that include the elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention. The scope of the present invention is defined by the appended claims and equivalents thereof.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.
Hereinafter, the invention described in the scope of claims of the present application will be appended.
[1] A diaphragm formed on a silicon substrate, a piezoelectric drive element including a lower electrode, a piezoelectric film, and an upper electrode on the diaphragm, a nozzle formed on the diaphragm, and adjacent to the diaphragm. And a collective head formed by arranging a plurality of cells of the ink ejecting portion having a pressure generating chamber formed in the above-described manner, and the collective head is connected to either the upper electrode or the lower electrode that drives the cell. An ink jet recording head in which connected lead wires for individual driving are formed over the diaphragm on the pressure generating chamber of another cell.
[2] In the collecting head, the cells are arranged in a plurality of rows along the paper feeding direction and in a plurality of stages along a direction orthogonal to the paper feeding direction, and are arranged at both ends along the paper feeding direction of the collecting head. An external electrode for individual driving of the cell and a common electrode for the cell are formed, and the lower electrode is connected to the lead wiring for the individual driving, and is arranged on the inner side along the paper feeding direction of the collective head The lead wiring of the lower electrode of the cell formed over the diaphragm on the pressure generation chamber of another cell adjacent to the outside along the paper feeding direction of the collecting head is formed. The ink jet recording head according to claim 1.
[3] In the collecting head, the cells are arranged in a plurality of rows along the paper feeding direction and in a plurality of stages along a direction perpendicular to the paper feeding direction, and at both ends along the paper feeding direction of the collecting head. An external electrode for individual driving of the cell and a common electrode for the cell are formed, and the upper electrode is connected to the lead wiring for the individual driving, and is arranged on the inner side along the paper feeding direction of the collective head The lead wiring of the upper electrode of the cell formed over the diaphragm on the pressure generating chamber of the other cell adjacent to the outside along the paper feeding direction of the collecting head is formed. The ink jet recording head according to claim 1.
[4] The silicon substrate is located on an end surface of the silicon substrate opposite to a surface on which the ink ejecting portion is formed, and a first connection port that supplies ink to the pressure generating chamber; and the pressure generation A back plate having a second connection port through which ink flows out of the chamber, and the silicon substrate is integrally formed on an end surface on the back plate side, and the communication path in the vicinity of the nozzle is formed in the pressure generating chamber. The ink jet recording head according to claim 1, further comprising a partition wall that divides into a plurality of partitions except for the ink jet recording head.
[5] The collective head is a dummy wiring that adjusts a driving condition on the diaphragm of the cell in which the extraction wiring of the other cell is formed over the diaphragm on the pressure generating chamber. The ink jet recording head according to claim 1, wherein the ink jet recording head is disposed.
[6] The ink jet recording head according to [5], wherein the dummy wiring is formed in a shape corresponding to the lead-out wiring.
[7] An ink jet recording apparatus having the ink jet recording head according to any one of claims 1 to 6.

    DESCRIPTION OF SYMBOLS 6 ... Inkjet head, 10 ... Silicon substrate, 11 ... Side wall, 12, 12a, 12b ... Pressure generating chamber, 21 ... Vibration plate, 30 ... Piezoelectric element (piezoelectric drive element), 31 ... Lower electrode, 32 ... Piezoelectric film, 33 DESCRIPTION OF SYMBOLS ... Upper electrode, 41 ... Lead-out wiring, 42 ... External electrode, 44 ... Dummy wiring, 53 ... Nozzle, 61 ... Common wiring, 63 ... Common electrode, 70 ... Individual cell, 100 ... Inkjet printer.

Claims (7)

A diaphragm formed on a silicon substrate;
A piezoelectric drive element comprising a lower electrode, a piezoelectric film and an upper electrode on the diaphragm;
A nozzle formed on the diaphragm;
An assembly head in which a plurality of cells of an ink ejecting unit having a pressure generating chamber formed adjacent to the vibration plate inside the silicon substrate are disposed;
The collective head is formed so that an outer shape of the piezoelectric driving element is smaller than an outer shape of the pressure generating chamber, and an extraction wiring connected to either the upper electrode or the lower electrode is connected to the other of the cells. An ink jet recording head formed over the diaphragm above the pressure generating chamber. In the collecting head, the cells are arranged in a plurality of rows along the paper feeding direction and in a plurality of stages along a direction orthogonal to the paper feeding direction.
External electrodes for individual driving of the cells and common electrodes of the cells are formed at both ends along the paper feeding direction of the collecting head,
The lower electrode is connected to the lead wire for the individual drive,
The lead-out wiring of the lower electrode of the cell arranged inside along the paper feed direction of the collective head is the pressure generation chamber of another cell adjacent to the outside along the paper feed direction of the collective head. The ink jet recording head according to claim 1, wherein the ink jet recording head is formed over the vibration plate on the substrate. In the collecting head, the cells are arranged in a plurality of rows along the paper feeding direction and in a plurality of stages along a direction orthogonal to the paper feeding direction.
External electrodes for individual driving of the cells and common electrodes of the cells are formed at both ends along the paper feeding direction of the collecting head,
The upper electrode, the lead wires are connected,
The lead wiring of the upper electrode of the cell arranged inside along the paper feed direction of the collective head is the pressure generating chamber of the other cell adjacent to the outside along the paper feed direction of the collective head. The ink jet recording head according to claim 1, wherein the ink jet recording head is formed over the vibration plate on the substrate. The silicon substrate is on an end surface of the silicon substrate opposite to the surface on which the ink ejecting portion is formed, and has a first connection port for supplying ink to the pressure generating chamber, and ink from the pressure generating chamber. And a second connection port through which the gas flows out,
2. The ink jet recording head according to claim 1, wherein the silicon substrate is formed integrally with an end face on the back plate side, and has a partition wall that divides the pressure generating chamber into a plurality of portions excluding a communication path near the nozzle.   The collective head is provided with a dummy wiring for adjusting a driving condition on the diaphragm of the cell in which the extraction wiring of the other cell is formed over the diaphragm on the pressure generating chamber. The ink jet recording head according to claim 1.   The ink jet recording head according to claim 5, wherein the dummy wiring is formed in a shape corresponding to the lead wiring.   An ink jet recording apparatus comprising the ink jet recording head according to claim 1.