JPWO2015163069A1 - Inkjet head and inkjet printer - Google Patents

Abstract

The ink jet head (21) sandwiches a support substrate (11) having a pressure chamber (11a) between a vibration plate (12) and a nozzle plate (13), and vibrates the vibration plate (12) by a drive element (14). Thus, the ink in the pressure chamber (11a) is ejected to the outside through the nozzle holes (13a) of the nozzle plate (13). The support substrate (11) has a plurality of pressure chambers (11a) and surrounds each pressure chamber (11a) with a substantially constant thickness within a plane along the diaphragm (12) and the nozzle plate (13). It has a wall (11b). The wall (11b) is provided independently for each pressure chamber (11a) and has the same outer shape.

Description

  The present invention relates to an ink jet head that discharges ink in a pressure chamber to the outside, and an ink jet printer that includes the ink jet head.

  2. Description of the Related Art Conventionally, an ink jet printer including an ink jet head having a plurality of channels (ink ejection portions) for ejecting ink is known. By controlling the ejection of ink while moving the inkjet head relative to a recording medium such as paper or cloth, a two-dimensional image can be output to the recording medium. Ink can be ejected by using an actuator (piezoelectric, electrostatic, thermal deformation, etc.) or by generating bubbles in the ink in the tube by heat. Among them, the piezoelectric actuator has advantages such as high output, modulation, high responsiveness, and choice of ink, and has been frequently used in recent years.

  In addition, piezoelectric actuators include those using a bulk piezoelectric body and those using a thin film piezoelectric body (piezoelectric thin film). Since the former has a large output, large droplets can be discharged, but it is large and expensive. On the other hand, since the latter has a small output, the amount of droplets cannot be increased, but it is small in size and low in cost. In order to realize a small, low-cost printer with high resolution (small droplets may be sufficient), it can be said that it is suitable to configure an actuator using a piezoelectric thin film. In the piezoelectric actuator, whether to use a piezoelectric thin film or a bulk piezoelectric body may be selected depending on the application.

  FIG. 14 is a plan view showing a schematic configuration of a conventional inkjet head 100 using a piezoelectric actuator, a sectional view taken along line AA ′ in the plan view, and a line BB ′ in the sectional view. This is shown together with a cross-sectional view taken along the arrow. However, for convenience, in the plan view, the lower electrode 201 and the upper electrode 203 of the drive element 104 described later are not shown. In the ink jet head 100, a support substrate 101 having a plurality of pressure chambers 101a is sandwiched between a vibration plate 102 and a nozzle plate 103, and a drive element 104 including a piezoelectric body is formed on the vibration plate 102 above each pressure chamber 101a. Configured. The nozzle plate 103 is formed with nozzle holes 103a for discharging the ink in each pressure chamber 101a to the outside.

  In addition to the plurality of pressure chambers 101a, two ink flow paths 101b are formed in parallel on the support substrate 101. The plurality of pressure chambers 101a are formed in two rows in a staggered manner between the two ink flow paths 101b and 101b. The pressure chambers 101a in one row communicate with one ink flow path 101b through a communication path 101c, and the pressure chambers 101a in the other row communicate with the other ink flow path 101b through a communication path 101c. Communicate. Further, one end of each ink flow path 101 b communicates with an ink storage portion (ink storage tank) (not shown) via an ink supply port 105, and the other end communicates with an ink storage portion via an ink discharge port 106. doing.

  FIG. 15 is a cross-sectional view showing a schematic configuration of one channel of the inkjet head 100. A driving element 104 is formed on the vibration plate 102 with an insulating layer 107 interposed therebetween. The drive element 104 is configured by laminating a lower electrode 201, a piezoelectric body 202, and an upper electrode 203 in order from the diaphragm 102 side. When a voltage is applied from the drive circuit 108 to the lower electrode 201 and the upper electrode 203, the piezoelectric body 202 expands and contracts in a direction perpendicular to the thickness direction. Then, due to the difference in length between the piezoelectric body 202 and the diaphragm 102, a curvature occurs in the diaphragm 102, and the diaphragm 102 is displaced (curved) in the thickness direction. By applying pressure to the pressure chamber 101a by such displacement of the vibration plate 102, the ink in the pressure chamber 101a is ejected to the outside through the nozzle hole 103a.

Perovskite metal oxides such as barium titanate (BaTiO ₃ ) and lead zirconate titanate (Pb (Ti / Zr) O ₃ ) called PZT are widely used for the piezoelectric body 202 used in the drive element 104. ing. When the piezoelectric body is composed of a piezoelectric thin film, for example, PZT is formed on the substrate by film formation. PZT can be formed by various methods such as sputtering, CVD (Chemical Vapor Deposition), and sol-gel. Note that silicon (Si) is often used for the substrate because high temperature is required for crystallization of the piezoelectric material.

  16 shows a cross-sectional view taken along the line C-C ′ of FIG. 14 and shows a deformed shape of the diaphragm 102 that is deformed by the expansion and contraction of the drive element 104. The rigidity (support rigidity) for supporting the diaphragm 102 in the support substrate 100 varies depending on the structure of the support substrate 100 around the channel. For example, in FIG. 16, the support substrate 101 has no digging portion on the left side of the pressure chamber 101a, so that the support rigidity of the diaphragm 102 is high. On the right side of the pressure chamber 101a, ink that is a digging portion is formed on the support substrate 101. Since the flow path 101b is formed, the support rigidity of the diaphragm 102 is low.

  Thus, if there is a difference in support rigidity between the left and right sides of the pressure chamber 101a, the deformed shape of the diaphragm 102 becomes asymmetric in the left-right direction of the pressure chamber 101a even if the drive element 104 expands and contracts uniformly in the plane. . As a result, the distribution of pressure applied to the ink in the pressure chamber 101a becomes asymmetric, which causes a decrease in the ink discharge speed, a fall in the discharge angle, and the like. Further, when the support rigidity of the diaphragm 102 is changed, the resonance frequency of the actuator is changed, so that the responsiveness is also changed.

  Further, the ejection speed, ejection angle, and responsiveness of ink change depending on whether or not adjacent channels are driven. FIG. 17 shows a deformed shape of the diaphragm 102 in the central channel when three channels are formed side by side in the inkjet head 100. When the left and right channels are not driven with respect to the center channel as in the pattern 1, when the center channel is driven, the diaphragm 102 of the channel is deformed symmetrically in the left-right direction and the amount of deformation Can also be obtained.

  However, when a certain channel is driven, deformation and vibration of the diaphragm 102 are also transmitted to the surrounding channels via the support substrate 101 and the nozzle plate 103. For this reason, as shown in pattern 2, when the center channel is driven, the left channel is also driven, and when the right channel is not driven, the diaphragm 102 of the center channel is pulled to the left. Becomes asymmetric in the left-right direction. As a result, the ejection speed and ejection angle of the ink ejected from the central channel change. Further, when the left and right channels are driven in addition to the center channel as in the pattern 3, the diaphragm 102 of the center channel is pulled to both the left side and the right side. Although it is symmetric in the direction, the amount of deformation is smaller than that of the pattern 1. As a result, the ink ejection speed decreases.

  Further, when the diaphragm 102 is pulled, stress acts on the adjacent channel, so that the resonance frequency increases and the response changes. The manner and degree of influence of adjacent channels vary depending on the degree of deformation of the diaphragm 102, the distance to the adjacent channel, the rigidity of the support substrate 101, the manner of support of the diaphragm 102, and the like.

  As described above, when the ink ejection speed, ejection angle, and responsiveness change due to the shape of the periphery of the channel and the influence of adjacent channels, the ink ejected from each channel reaches the desired position on the recording medium. Therefore, the image quality deteriorates. In particular, when a plurality of pressure chambers 101a are arranged at a high density, the influence of changes in the discharge speed, discharge angle, and responsiveness becomes larger, and the image quality further deteriorates.

  Thus, conventionally, a method for making the ink ejection characteristics of each channel uniform has been proposed. For example, in Patent Document 1, among a plurality of channels arranged in a matrix, a channel structure (for example, a pressure chamber shape or a piezoelectric element shape) located at an outer edge is used as a channel structure located inside the channel structure. By making them different, the ink ejection characteristics are made uniform in each channel. Further, in Patent Documents 2 and 3, a plurality of channels for ejecting ink are arranged in a matrix, and a dummy channel that does not eject ink is disposed around the channels (outer peripheral portion), so that the ink ejection characteristics are set for each channel. To make it uniform.

Japanese Patent Laying-Open No. 2005-169638 (see claims 1, 4-6, paragraphs [0013], [0036], FIG. 4, FIG. 7, etc.) Japanese Patent Laying-Open No. 2005-41139 (see claims 1 and 2, paragraphs [0011], [0032], [0040], [0042], FIG. 1, FIG. 2, FIG. 4 etc.) JP 2004-358872 A (refer to Claims 1 and 3, paragraphs [0017] to [0023], FIG. 2, FIG. 4, FIG. 5, etc.)

  However, in the method of Patent Document 1, since the structure is changed between the outer edge channel and the inner channel, the design and production costs are high. Further, in the methods of Patent Documents 2 and 3, since a space for providing a dummy channel is required, it is difficult to realize a reduction in the size of the head and a high-density arrangement of the channels.

  The above problem occurs regardless of whether the piezoelectric body that drives each channel is a bulk or a thin film.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is to reduce the size of the head and arrange the channels at a high density while achieving uniform ink ejection characteristics in each channel at a low cost. It is another object of the present invention to provide an ink jet head that can also be realized, and an ink jet printer including the ink jet head.

  An ink jet head according to one aspect of the present invention sandwiches a support substrate having a pressure chamber between a vibration plate and a nozzle plate, and vibrates the vibration plate by a driving element, thereby causing ink in the pressure chamber to flow through the nozzles of the nozzle plate. An inkjet head that discharges to the outside through a hole, wherein the support substrate has a plurality of pressure chambers, and each pressure chamber is substantially constant in a plane along the vibration plate and the nozzle plate. The wall portion is surrounded by a thickness, and the wall portion is provided independently for each of the pressure chambers and has the same outer shape.

  With a low-cost configuration, the ink ejection characteristics can be made uniform in each channel, the image quality can be improved, and the head can be downsized and the channels can be arranged at high density.

1 is an explanatory diagram illustrating a schematic configuration of an inkjet printer according to an embodiment of the present invention. FIG. FIG. 3 is a plan view, a cross-sectional view taken along line A-A ′, and a cross-sectional view taken along line B-B ′, showing a schematic configuration of an inkjet head included in the inkjet printer. It is sectional drawing which expands and shows one channel in the said inkjet head. FIG. 3 is a cross-sectional view schematically showing the flow of ink during ink circulation in the inkjet head. It is sectional drawing which shows the flow of the ink in one channel. It is sectional drawing which shows the other structure of the said channel typically. It is sectional drawing which shows the manufacturing process of the said inkjet head. It is a flowchart which shows the flow of operation | movement including the ink circulation process in the said inkjet head. It is the vertical sectional view and horizontal sectional view which show the other structure of the said inkjet head. It is a horizontal sectional view which shows the variation of the external shape of a wall part. It is a horizontal sectional view showing other composition of the above-mentioned ink jet head. It is a horizontal sectional view showing other composition of the above-mentioned ink jet head. It is a horizontal sectional view showing other composition of the above-mentioned ink jet head. FIG. 8 is a plan view, a cross-sectional view taken along line A-A ′, and a cross-sectional view taken along line B-B ′, showing a schematic configuration of a conventional inkjet head. It is sectional drawing which shows the schematic structure of one channel of the said inkjet head. FIG. 15 is a cross-sectional view taken along the line C-C ′ of FIG. It is sectional drawing of the conventional inkjet head in which three channels are formed side by side, and explanatory drawing which shows the deformation | transformation shape of the diaphragm of a center channel.

  An embodiment of the present invention will be described below with reference to the drawings.

[Configuration of inkjet printer]
FIG. 1 is an explanatory diagram illustrating a schematic configuration of an inkjet printer 1 according to the present embodiment. The ink jet printer 1 is a so-called line head type ink jet recording apparatus in which an ink jet head 21 is provided in a line shape in the width direction of a recording medium in the ink jet head unit 2.

  The ink jet printer 1 includes an ink jet head unit 2, a feed roll 3, a take-up roll 4, two back rolls 5 and 5, an intermediate tank 6, a liquid feed pump 7, a storage tank 8, and a fixing tank. And a mechanism 9.

  The ink jet head unit 2 ejects ink from the ink jet head 21 toward the recording medium P to perform image formation (drawing) based on image data, and is disposed in the vicinity of one back roll 5. The configuration of the inkjet head 21 will be described later.

  The feed roll 3, the take-up roll 4 and the back rolls 5 are members each having a cylindrical shape that can rotate about its axis. The feeding roll 3 is a roll that feeds the long recording medium P wound around the circumferential surface toward the position facing the inkjet head unit 2. The feeding roll 3 is rotated by driving means (not shown) such as a motor, thereby feeding the recording medium P in the X direction in FIG.

  The take-up roll 4 is taken out from the take-out roll 3 and takes up the recording medium P on which the ink is ejected by the inkjet head unit 2 around the circumferential surface.

  Each back roll 5 is disposed between the feed roll 3 and the take-up roll 4. One back roll 5 located on the upstream side in the conveyance direction of the recording medium P is opposed to the inkjet head unit 2 while winding the recording medium P fed by the feeding roll 3 around and supporting the recording medium P. Transport toward The other back roll 5 conveys the recording medium P from a position facing the inkjet head unit 2 toward the take-up roll 4 while being wound around and supported by a part of the peripheral surface.

  The intermediate tank 6 temporarily stores the ink supplied from the storage tank 8. The intermediate tank 6 is connected to the ink tube 10, adjusts the back pressure of the ink in each inkjet head 21, and supplies the ink to each inkjet head 21.

  The liquid feed pump 7 supplies the ink stored in the storage tank 8 to the intermediate tank 6 and is disposed in the middle of the supply pipe 11. The ink stored in the storage tank 8 is pumped up by the liquid feed pump 7 and supplied to the intermediate tank 6 through the supply pipe 11.

  The fixing mechanism 9 fixes the ink ejected to the recording medium P by the inkjet head unit 2 on the recording medium P. The fixing mechanism 9 includes a heater for heat-fixing the discharged ink on the recording medium P, a UV lamp for curing the ink by irradiating the discharged ink with UV (ultraviolet light), and the like. Yes.

  In the above configuration, the recording medium P fed from the feeding roll 3 is transported to a position facing the inkjet head unit 2 by the back roll 5, and ink is ejected from the inkjet head unit 2 to the recording medium P. Thereafter, the ink ejected onto the recording medium P is fixed by the fixing mechanism 9, and the recording medium P after ink fixing is taken up by the take-up roll 4. As described above, in the line head type inkjet printer 1, ink is ejected while the recording medium P is conveyed while the inkjet head unit 2 is stationary, and an image is formed on the recording medium P.

  The ink jet printer 1 may be configured to form an image on a recording medium by a serial head method. The serial head method is a method of forming an image by ejecting ink by moving an inkjet head in a direction (width direction) orthogonal to the transport direction while transporting a recording medium. In this case, the ink jet head moves in the width direction of the recording medium while being supported by a structure such as a carriage.

[Configuration of inkjet head]
Next, the configuration of the inkjet head 21 will be described. FIG. 2 is a plan view showing a schematic configuration of the inkjet head 21 described above, a cross-sectional view taken along line AA ′ in the plan view, and a cross-sectional view taken along line BB ′ in the cross-sectional view. It is shown. However, for convenience, in the plan view, the lower electrode and the upper electrode of the driving element 14 described later are omitted.

  The ink jet head 21 of this embodiment is configured such that a support substrate 11 having a plurality of pressure chambers 11a is sandwiched between a diaphragm 12 and a nozzle plate 13 having a constant thickness, and is driven on the diaphragm 12 above each pressure chamber 11a. The element 14 is formed and configured. The drive element 14 is configured by laminating a lower electrode, a piezoelectric thin film, and an upper electrode in this order from the diaphragm 12 side. The lower electrode and the upper electrode are connected to a drive circuit (not shown). The thickness of the piezoelectric thin film is 1 μm to 10 μm, which is a thin film piezoelectric body. Nozzle holes 13a are formed in the nozzle plate 13 corresponding to the pressure chambers 11a.

  The support substrate 11 is formed with a plurality of pressure chambers 101a and wall portions 11b. Each pressure chamber 101a is formed in two rows in a staggered manner on the support substrate 11. The wall portion 11 b is a so-called side wall that forms a wall around the pressure chamber 11 a (between the vibration plate 12 and the nozzle plate 13) in the support substrate 11, and is in-plane along the vibration plate 12 and the nozzle plate 13. Each pressure chamber 11a is provided so as to surround the pressure substrate 11a with a substantially constant thickness (in a plane perpendicular to the thickness direction of the support substrate 11). Note that the thickness of the wall portion 11b being substantially constant means that the fluctuation range of the thickness of the wall portion 11b is within ± 20% (more preferably within ± 10%) of the reference thickness.

  Each wall portion 11b is provided independently for each pressure chamber 11a (corresponding to each pressure chamber 11a in one-to-one correspondence). “Independent” is preferably not serving as the wall portion 11b of the adjacent pressure chamber 11a, but as shown in FIG. 12, the wall portion 11b and a part of the wall portion 11b are connected to each other. It shall be included in “independence” in the present application. In this case, the “part” is within 10% of the surface area of the wall portion 11b, desirably within 5%.

  Further, all the wall portions 11b have the same outer shape, and in this embodiment, for example, are circular in a plane along the diaphragm 12 and the nozzle plate 13. In addition, the surface along the diaphragm 12 and the nozzle plate 13 is also referred to as “in the horizontal section” below.

  In the case of the example shown in FIG. 2, the support substrate 11 includes a plurality of cylinders (wall portions 11 b) instead of a single plate. In the present application, such a substrate is also referred to as a “support substrate”.

  In the support substrate 11, around each wall portion 11b (on the side opposite to the pressure chamber 11a), a hole from which a part of the support substrate 11 is removed in the substrate thickness direction (the support substrate 11 in the substrate thickness direction). An excavated portion) 18 is formed. The holes 18 allow the wall portions 11b to be positioned away from each other (not connected) via the hole portions 18, and the wall portions 11b are independently arranged so as to correspond to the pressure chambers 11a. It becomes possible to do. It is also possible to position each wall portion 11b away from surrounding structures (for example, a carriage that supports the head). In the present embodiment, the hole 18 is a through-hole that penetrates the support substrate 11 in the thickness direction, and constitutes an ink flow path 18a for supplying ink to each pressure chamber 11a.

  Each of the wall portions 11b described above has a communication passage 11c for communicating the pressure chamber 11a surrounded by the wall portion 11b with the ink flow path 18a around the wall portion 11b. A plurality of communication paths 11c are provided for each of the wall portions 11b surrounding each pressure chamber 11a, and two communication paths 11c are provided in the present embodiment. These two communicating portions 11c are located at positions opposite to each other with respect to the pressure chamber 11a surrounded by the wall portion 11b in the horizontal cross section (at positions that are point-symmetric with respect to the center of the pressure chamber 11a within the horizontal cross section). ) Is provided. Each wall portion 11b is provided on the support substrate 11 so that a plurality of communication paths 11c are arranged along one direction (left and right direction in the horizontal sectional view of FIG. 2).

  The support substrate 11 further includes an ink supply port 11d and an ink discharge port 11e. The ink supply port 11d is a supply port for supplying ink from the storage tank 8 (see FIG. 1) serving as an ink storage unit to the ink flow path 18a, and the storage tank is provided via a passage 19a inside the ink supply unit 19. 8 communicates. The ink discharge port 11 e is a discharge port for discharging ink from the ink flow path 18 a to the storage tank 8, and communicates with the storage tank 8 through a passage 20 a inside the ink discharge unit 20.

  Each of the wall portions 11b described above is located between the ink supply port 11d and the ink discharge port 11e in the horizontal cross section. The ink supply port 11d is provided on one side (left side in the horizontal sectional view of FIG. 2) in which the communication path 11c is arranged, and the ink discharge port 11e is provided on the other side in the one direction ( It is provided on the right side in the horizontal sectional view of FIG.

  When ink is introduced into the ink flow path 18a from the ink supply port 11d, the ink is supplied into the pressure chambers 11a through the communication paths 11c of the wall portions 11b. Then, when the vibration plate 12 is vibrated by the driving element 14, the ink in each pressure chamber 11a is ejected to the outside through the nozzle hole 13a. More specifically, when a voltage is applied to the lower electrode and the upper electrode of the drive element 14 by a drive circuit (not shown), the piezoelectric thin film expands and contracts and the diaphragm 12 deforms (vibrates), thereby causing the ink in the pressure chamber 11a to be changed. Pressure is applied and ink droplets are ejected from the nozzle holes 13a. When the vibration plate 12 returns to the original position after the ink is discharged, the pressure chamber 11a becomes negative pressure, and the ink flows into the pressure chamber 11a via the communication path 11c. Thereafter, such a process is repeated.

  FIG. 3 is an enlarged cross-sectional view of a portion D of FIG. 2, that is, one channel (ink ejection portion). In the support substrate 11, since the thickness of each wall part 11b is substantially constant, the support rigidity of the diaphragm 12 supported by each wall part 11b is substantially the same at any position around the pressure chamber 11a in the horizontal section. Become. As a result, when the vibration plate 12 vibrates by the drive element 14, the deformation shape of the vibration plate 12 can be made symmetrical even in a plane perpendicular to the vibration plate 12, and thereby the pressure chamber 11a. The distribution of pressure applied to the ink inside can be made symmetrical.

  In addition, since each wall portion 11b is provided independently for each pressure chamber 11a, the diaphragm 12 supported by each wall portion 11b vibrates almost without being affected by the drive of the adjacent pressure chamber 11a. (Deformation) is possible. Moreover, since each wall part 11b is provided in the same external shape, it does not cost a design or manufacture unlike the case where it forms in a different shape.

  Therefore, with a low-cost configuration, ink ejection characteristics such as ejection speed, ejection angle, and responsiveness can be made uniform among a plurality of channels, and the deformation amount and resonance frequency of the diaphragm 12 can be made uniform among the channels. , Image quality can be improved. Further, since the ink ejection characteristics can be made uniform in each channel without providing dummy channels as in the prior art, it is possible to realize a reduction in the size of the head and a high density arrangement of the channels.

An example of the size of the head for obtaining the above effect is as follows. That is, it has been confirmed by experiments that the above effects can be obtained when the head is configured with the following dimensions.
Pressure chamber diameter (within horizontal section): 500 μm
Diaphragm thickness: 10 μm
Piezoelectric thin film diameter (within horizontal section): 400 μm
Piezoelectric thin film thickness: 10 μm
Wall thickness (within horizontal section): 50 μm
Support substrate thickness: 300 μm

  Further, since the hole 18 is formed in the support substrate 11, the adjacent walls 11 b and 11 b can be positioned apart from each other via the hole 18. Accordingly, it is possible to reliably suppress the deformation of the diaphragm 12 supported by each wall portion 11b and driving each pressure chamber 11a from being disturbed by the influence of the driving of the adjacent pressure chamber 11a.

  Further, when the hole portion 18 is not formed in the support substrate 11 and each wall portion 11b is not formed independently corresponding to each pressure chamber 11a, the support rigidity of the diaphragm 12 is that of the adjacent channel. Also depending on the number and position, the distance between the peripheral portion such as the ink supply port 11d and the ink discharge port 11e and the pressure chamber 11a, the distance between the structure (not shown) such as a carriage supporting the head and the pressure chamber 11a, etc. Change. However, the formation of the hole 18 described above can prevent the wall portion 11b and the surrounding structure and the like from being directly connected to each other. Therefore, the support rigidity of the diaphragm 12 can be increased between the channels while reliably eliminating these effects. Can be surely uniform.

  Further, since the hole portion 18 constitutes the ink flow path 18 a, the space formed by the hole portion 18 can be used effectively, compared with a configuration in which the ink flow path is formed at another position of the support substrate 11. Thus, the head can be further miniaturized.

  Moreover, since each wall part 11b has the communicating path 11c, it becomes possible to supply reliably the ink which flows through the ink flow path 18a to the pressure chamber 11a via the communicating path 11c. In particular, as in the present embodiment, a plurality of (for example, two) communication paths 11c are provided for each of the wall portions 11b surrounding the pressure chamber 11a. It becomes possible to circulate with.

4 is a cross-sectional view schematically showing the flow of ink during ink circulation in the inkjet head 21, and FIG. 5 is a cross-sectional view showing the flow of ink in one channel. When two communication paths 11c ₁ and 11c ₂ are provided as the communication path 11c in _one wall portion 11b, the ink flowing through the ink flow path 18a flows into the pressure chamber 11a through the _one communication path 11c _1. is supplied, is discharged from the pressure chamber 11a via the other communication path c _2, returns to the ink flow path 18a.

Thus, since one communication path 11c ₁ can be used for supplying ink to the pressure chamber 11a and the other communication path 11c ₂ can be used for discharging ink from the pressure chamber 11a, By circulating ink outside, it becomes possible to remove bubbles and foreign substances (including precipitates) accumulated in the pressure chamber 11a, and abnormal ink ejection (such as ejection speed and ejection angle) due to bubbles and the like. Defects, non-ejection of ink, etc.) can be reliably reduced.

In particular, the two communication paths 11c (11c ₁ and 11c ₂ ) are provided at positions opposite to each other with respect to the pressure chamber 11a in the horizontal cross section, so that the ink in the pressure chamber 11a has two pieces. Since it becomes easy to flow in one direction passing through the communication path 11c, ink circulation efficiency can be improved.

  Further, as shown in the horizontal sectional view of FIG. 2, each wall portion 11b is provided on the support substrate 11 so that the communication passages 11c of each wall portion 11b are arranged along one direction. Accordingly, it is possible to circulate ink so as to flow in series in each pressure chamber 11a, and it is possible to circulate ink in a plurality of pressure chambers 11a simultaneously.

  In the support substrate 11, the ink supply port 11d is provided on one side in one direction in which the plurality of communication paths 11c are arranged, and the ink discharge port 11e is provided on the other side in the one direction. Therefore, the ink supplied from the ink supply port 11d to the ink flow path 18a flows in series through the pressure chambers 11a via the communication path 11c and travels toward the ink discharge port 11e. Therefore, the ink in the plurality of pressure chambers 11a can be efficiently circulated with the storage tank 8 through the ink supply port 11d and the ink discharge port 11e.

FIG. 6 is a cross-sectional view schematically showing another configuration of one channel of the ink jet head 21. As shown in the figure, at least one of the plurality of communication portions 11c (for example, the communication passage 11c ₂ ) provided in the same wall portion 11b may have the same depth as the substrate thickness of the support substrate 11. . In this case, it is possible bubbles or foreign matter accumulated in the upper portion of the pressure chamber 11a is discharged efficiently through the communication passage 11c _2. In particular, among a plurality of communication paths 11c provided in the same wall portion 11b, the position is located on the most downstream side in the direction in which ink flows from the ink supply port 11d to the ink discharge port 11e through the pressure chamber 11a during ink circulation. By making the depth of the communication path 11c ₂ to be the same as the substrate thickness of the support substrate 11, the communication path 11c ₂ becomes a communication path for discharging ink during ink circulation, so that air bubbles accumulated in the upper portion of the pressure chamber 11a. And the above-described effect of discharging foreign matter can be reliably obtained.

[Inkjet head manufacturing method]
Next, the manufacturing method of the inkjet head 21 of this embodiment is demonstrated below. FIG. 7 is a cross-sectional view showing the manufacturing process of the inkjet head 21.

  First, the substrate 31 is prepared. As the substrate 31, crystalline silicon (Si) often used for MEMS (Micro Electro Mechanical Systems) can be used. Here, two Si substrates 31a and 31c are bonded via an oxide film 31b. An SOI structure is used. The thickness of the substrate 31 is determined by a standard or the like. For example, in the case of a 6-inch size, the thickness of the substrate 31 is about 600 μm.

The substrate 31 is placed in a heating furnace and held at about 1500 ° C. for a predetermined time, and thermal oxide films 32 a and 32 b made of SiO ₂ are formed on the surfaces of the Si substrates 31 a and 31 c, respectively. Next, each layer of titanium and platinum is sequentially formed on one thermal oxide film 32b by a sputtering method to form the lower electrode 33.

  Subsequently, the substrate 31 is reheated to about 600 ° C., and a layer 34a made of, for example, PZT is formed by sputtering. Next, a photosensitive resin 41 is applied to the substrate 31 by a spin coating method, and unnecessary portions of the photosensitive resin 41 are removed by exposure and etching through a mask, and the shape of the piezoelectric thin film 34 to be formed is transferred. . Thereafter, using the photosensitive resin 41 as a mask, the shape of the layer 34 a is processed using a reactive ion etching method to form the piezoelectric thin film 34.

  Next, a titanium layer and a platinum layer are sequentially formed by sputtering on the lower electrode 33 so as to cover the piezoelectric thin film 34, thereby forming a layer 35a. Subsequently, a photosensitive resin 42 is applied onto the layer 35a by a spin coating method, and unnecessary portions of the photosensitive resin 42 are removed by exposure and etching through a mask, and the shape of the upper electrode 35 to be formed is transferred. To do. Thereafter, using the photosensitive resin 42 as a mask, the shape of the layer 35a is processed using a reactive ion etching method to form the upper electrode 35.

  Next, a photosensitive resin 43 is applied to the back surface (thermal oxide film 32a side) of the substrate 31 by a spin coating method, and unnecessary portions of the photosensitive resin 43 are removed by exposing and etching through a mask. The shape of the pressure chamber 51a, wall 51b, hole 52 (ink channel 52a), communication path (not shown), etc. to be formed is transferred. Then, using the photosensitive resin 43 as a mask, the substrate 31 is removed using a reactive ion etching method to form the pressure chamber 51a and the like.

  Then, the board | substrate 31 and the nozzle plate 36 which has the nozzle hole 36a are joined using an adhesive agent etc. Thereby, the inkjet head 21 is completed. The intermediate glass having a through hole at a position corresponding to the nozzle hole 36a is used, the thermal oxide film 32a is removed, and the substrate 31 and the intermediate glass, and the intermediate glass and the nozzle plate 36 are respectively anodically bonded. Also good. In this case, the three parties (substrate 31, intermediate glass, nozzle plate 36) can be joined without using an adhesive.

  The Si substrate 31a and the oxide film 31b in FIG. 7 correspond to the support substrate 11 in FIG. 1 and the like, the Si substrate 31c corresponds to the vibration plate 12, the nozzle plate 36 corresponds to the nozzle plate 13, and the lower electrode 33. The piezoelectric thin film 34 and the upper electrode 35 correspond to the drive element 14. The pressure chamber 51a, the wall 51b, and the hole 52 (ink flow path 52a) correspond to the pressure chamber 11a, the wall 11b, and the hole 18 (ink flow path 18a), respectively.

[Ink circulation timing]
The above-described ink circulation can be performed, for example, at the following timing. FIG. 8 is a flowchart showing an operation flow including an ink circulation process in the inkjet head 21 of the present embodiment.

  First, when the power of the inkjet printer 1 is turned on (S1), an ink circulation operation is performed by a pump or the like (not shown) (S2). Subsequently, the number N of prints is set to N = 1 (S3), and the ink is discharged. An operation is performed (S4). Thereafter, N = N + 1 is set (S5), and a control unit (not shown) determines whether printing has been completed up to the last page (S6). If the printing is finished in S6, the ink circulation operation is performed again (S7), and the series of operations is finished.

  On the other hand, if printing has not ended in S6, it is determined whether n is a natural number, A is a predetermined number (for example, 50 sheets), and the number N of printed sheets is N = n · A ( S8). If N = n · A is not satisfied in S8 (if the number of printed sheets has not reached the predetermined number), it is determined that there is no need to perform ink circulation, and the operations after S4 are repeated. On the other hand, when N = n · A in S8 (when the number of printed sheets reaches a predetermined number), it is determined that it is necessary to remove bubbles and foreign matters by printing a predetermined number of sheets (S9). Thereafter, the operations after S4 are repeated.

  The print image and the vicinity of the nozzles are observed with a camera, and ink circulation may be performed if an ejection abnormality has occurred.

[Other configurations of inkjet head]
FIG. 9 shows a vertical sectional view and a horizontal sectional view showing another configuration of the inkjet head 21 together. 9 corresponds to the cross-sectional view taken along the line AA ′ in the horizontal cross-sectional view, and the horizontal cross-sectional view corresponds to the cross-sectional view taken along the line BB ′ in the vertical cross-sectional view. ing. Each wall portion 11b may have a shape with a different aspect ratio in the horizontal cross section. Here, the difference in aspect ratio means that a ≠ b when the vertical length is a (μm) and the horizontal length is b (μm). In FIG. 9, the outer shape of the wall portion 11b is an ellipse having a different aspect ratio in the horizontal cross section. And the communication path 11c is provided in two places in the major axis direction of the wall part 11b. The length of the elliptical wall 11b in the minor axis direction is the same as the diameter of the circular wall 11b shown in FIG.

  In this configuration, the deformation shape of the diaphragm 12 in a plane perpendicular to the diaphragm 12 varies depending on how the plane perpendicular to the diaphragm 12 is selected. For example, the deformed shape of the diaphragm 12 is different between a plane perpendicular to the diaphragm 12 and along the major axis direction of the wall portion 11b, and a plane along the minor axis direction of the wall portion 11b. However, in any of the above two planes, the deformation shape of the diaphragm 12 can be left-right symmetrical. Therefore, even with such a configuration, it is possible to make the ink ejection characteristics uniform between the channels.

  Further, in the configuration of FIG. 9, the displacement volume of the diaphragm 12 increases as the wall portion 11b is longer in the major axis direction than the configuration shown in FIG. 2 and the like (the outer shape of the wall portion 11b is circular). The ink discharge amount can be increased. In addition, since the short diameter of the wall portion 11b is not different from the configuration of FIG. 2 and the like, the change in the resonance frequency is small and ink can be ejected at high speed. Further, since the communication path 11c is formed side by side in the major axis direction of the wall portion 11b, bubbles and foreign matter in the pressure chamber 11a are easily removed during ink circulation.

  FIG. 10 is a horizontal sectional view showing variations in the outer shape of the wall 11b. As shown in the figure, the shape of the wall 11b in the horizontal cross section may be a square, a rectangle, a rhombus, or the like. When the outer shape of the wall 11b is square, the aspect ratio in the horizontal plane is the same as in the case of the circular shape, and when the outer shape is rectangular or rhombus, the aspect ratio in the horizontal plane is different.

  In particular, when the aspect ratio of the wall portion 11b in the horizontal plane is the same (circular, square), the deformation shape of the diaphragm 12 can be the same or substantially the same even in a plane perpendicular to the diaphragm 12. It becomes possible to make the ink ejection characteristics more uniform between the channels.

[Still other configurations of inkjet head]
FIG. 11 is a horizontal cross-sectional view showing still another configuration of the inkjet head 21. As shown in the figure, in the support substrate 11, a plurality of groups G each having at least one row in which a plurality of wall portions 11b are arranged in one direction (left-right direction in FIG. 11) may be formed in parallel. And in adjacent groups, each wall part 11b may be located in the said one direction and shifted | deviated by predetermined pitch P (micrometer). In this case, in the support substrate 11, the wall portions 11b and the pressure chambers 11a are arranged at a high density, so that higher-resolution image formation (ink ejection) is possible.

  In particular, as shown in FIG. 11, each group G has a plurality of rows in which a plurality of wall portions 11 b are arranged in one direction, and in adjacent rows in the same group G, each wall portion 11 b When the position is shifted by a predetermined pitch Q (μm) in the one direction, since the high-density arrangement of the pressure chambers 11a is realized in each group G, it is possible to form a higher resolution image. Become. In FIG. 11, since the number of groups G in the support substrate 11 is four, the predetermined pitch Q is set to 4P. However, the pitch is not limited to this.

  In FIG. 11, thick arrows indicate the flow of ink during ink circulation. As shown in the figure, the ink supplied from the ink supply ports 11d to the ink flow path 18a flows in series through the pressure chambers 11a via the communication passages 11c toward the ink discharge ports 11e. It can be circulated well.

  FIG. 12 is a horizontal sectional view showing still another configuration of the inkjet head 21. The support substrate 11 may further include a partition plate 22 for partitioning the ink flow path 18a outside each wall portion 11b. This configuration will be described more specifically as follows. In addition, about the arrangement | positioning pitch of each wall part 11b in the support substrate 11, since it is the same as that of the structure of FIG. 11, the description is abbreviate | omitted.

In the support substrate 11, each wall portion 11b is located between the plurality of ink supply ports 11d and the plurality of ink discharge ports 11e in the horizontal cross section. Each ink supply port 11d is provided on one side (left side in FIG. 12) in a direction (left and right direction in FIG. 12) perpendicular to one direction (up and down direction in FIG. 12) in which the communication paths 11c are arranged. The discharge port 11e is provided on the other side (right side in FIG. 12). The ink flow path 18a formed in the support substrate 11 is divided into a first ink flow path 18a ₁ communicating with one communication path 11c _{1 of} each wall portion 11b and the other communication path 11c ₂ by the partition plate 22. And a second ink channel 18a ₂ communicating with the second ink channel 18a ₂ . The ink supply port 11d is communicated with a _one first ink passage 18a, ink discharge port 11e communicates ₂ and the second ink flow path 18a. The partition plate 22 is formed by digging (removing) a part of the periphery of each wall portion 11b in the support substrate 11 in the substrate thickness direction. Therefore, in FIG. 12, the hole 18 is not formed so as to surround the entire periphery of each wall 11b.

In this configuration, the ink supplied from the ink supply port 11d to the first ink flow path 18a ₁ flows in parallel through the pressure chambers 11a and passes through the second ink flow path 18a ₂ to the ink discharge port 11e. Head. More specifically, the ink from the first ink flow passage 18a ₁ located on odd rows, enters the pressure chamber 11a through the communicating passage 11c _1, first located even row through the communicating passage 11c ₂ 2 To the ink flow path 18a ₂ and discharged. Therefore, even in this configuration, the ink in each pressure chamber 11a can be circulated between the outside.

In the configuration of FIG. 12, for example, the ink flowing through the first ink flow path 18 a ₁ in the third row causes each pressure chamber 11 a between the flow path in the second row and the flow path in the third row. Through the second ink flow path 18a ₂ located in the second row, and the pressure chambers 11a between the third row flow path and the fourth row flow path can be provided. It is also possible to pass through the second ink flow path 18a ₂ located in the fourth row.

The first ink flow path 18a ₁ and the second ink passage 18a _2, because it is partitioned by a partition plate 22 on the outside of each wall portion 11b, the first ink flow passage 18a ₁ second Ink flow to and from the ink flow path 18a ₂ is always performed through one of the pressure chambers 11a. Thereby, all the ink supplied from the ink supply port 11d can be used for the circulation of the ink in each pressure chamber 11a. Further, by providing the partition plate 22 as described above, a differential pressure is generated between the communication passages 11c ₁ and 11c _2, so that ink easily flows in the pressure chamber 11a, and bubbles and foreign matters in the pressure chamber 11a are discharged. It also has the effect of making it easier to

  FIG. 13 is a cross-sectional view showing still another configuration of the inkjet head 21. The hole 18 formed in the support substrate 11 may be a simple space without constituting the ink flow path 18a. Even in this case, since the adjacent wall portions 11b can be positioned apart from each other through a space, the deformation of the diaphragm 12 that drives each pressure chamber 11a affects the driving of the adjacent pressure chamber 11a. It is possible to reliably suppress the disturbance.

  However, in this case, an ink channel for supplying ink into the pressure chamber 11a is separately provided somewhere in the head, and an ink supply port and an ink discharge port communicating with the ink channel are provided in each pressure chamber 11a. It is necessary to provide it. For example, it is necessary to devise such as forming an ink supply port and an ink discharge port in the vibration plate 12 above the pressure chamber 11a, or providing a substrate having an ink flow path between the support substrate 11 and the nozzle plate 13. .

[Others]
In the present embodiment, the case where the piezoelectric body of the drive element 14 is configured by the piezoelectric thin film 34 (see FIG. 7) has been described, but the piezoelectric body may be a bulk. Even in this case, by adopting the configuration of the present embodiment, it is possible to make the ink ejection characteristics uniform between the channels.

The inkjet head 21 can also be configured by appropriately combining the configurations described in the present embodiment. For example, the configuration of FIG. 6 in which the depth of the communication path 11c ₂ is the same as the thickness of the support substrate 11 is combined with the configuration of FIGS. 9 to 12, or the shape of the wall portion 11b shown in FIGS. Of course, the inkjet head 21 can be configured by being applied to the arrangement of the wall portion 11b shown in FIGS.

  The ink jet head and ink jet printer of the present embodiment described above can be expressed as follows, and thereby have the following effects.

  The ink jet head of this embodiment sandwiches a support substrate having a pressure chamber between a vibration plate and a nozzle plate, and vibrates the vibration plate by a driving element, thereby causing ink in the pressure chamber to pass through the nozzle holes of the nozzle plate. The support substrate has a plurality of pressure chambers and surrounds each pressure chamber with a substantially constant thickness in a plane along the vibration plate and the nozzle plate. It has a wall part, and the said wall part is independently provided for every said pressure chamber, and the external shape is provided in the same shape.

  In the support substrate, since the thickness of the wall portion surrounding each pressure chamber in the plane along the diaphragm and the nozzle plate is substantially constant, the support rigidity of the diaphragm supported by the wall portion of the support substrate is It is almost the same at any position around the periphery (any position in the circumferential direction of the wall). Thereby, when the diaphragm is vibrated by the drive element, the deformation shape of the diaphragm is made symmetrical in the plane perpendicular to the diaphragm, and the distribution of pressure applied to the ink in the pressure chamber is made symmetrical. be able to.

  In addition, since the wall surrounding each pressure chamber is provided independently for each pressure chamber (since the plurality of pressure chambers do not have a common wall), the vibration supported by the wall of each pressure chamber The plate can vibrate (deform) almost without being affected by the drive of the adjacent pressure chambers. In addition, the walls of each pressure chamber are all provided with the same external shape (circular cross section, elliptical cross section, etc.), so that the design and production costs are high, as in the case of forming with different shapes. Nor.

  Therefore, according to the above configuration, it is possible to make the ink ejection characteristics (ejection speed, ejection angle, responsiveness, etc.) uniform between the pressure chambers, that is, between the plurality of channels ejecting ink, at low cost. Image quality can be improved.

  Further, in order to make the ink ejection characteristics uniform in each pressure chamber, it is not necessary to provide a head with a dummy channel that does not eject ink as in the prior art. It is also possible to realize (higher resolution of an image formed by ink ejection).

  In the support substrate, a hole from which a part of the support substrate is removed may be formed in at least a part of the periphery of the wall portion in the substrate thickness direction. In this case, since the adjacent wall portions can be positioned apart from each other through the hole portion, the deformation of the diaphragm driving each pressure chamber is disturbed by the influence of the driving of the adjacent pressure chamber. It can be surely suppressed.

  The hole portion may constitute an ink flow path for supplying ink to each pressure chamber. In this case, the space formed by the hole can be effectively used as the ink flow path. Further, the head can be further reduced in size as compared with the configuration in which the ink flow path is formed at another position of the support substrate.

  In the support substrate, the wall portion surrounding each pressure chamber may have a communication path for communicating the pressure chamber surrounded by the wall portion and the ink flow path around the wall portion. In this case, it is possible to reliably supply the ink flowing through the ink flow path to the pressure chamber via the communication path.

  A plurality of the communication passages may be provided per one wall portion surrounding each pressure chamber. In this case, some of the plurality of communication paths can be used for supplying ink to the pressure chamber, and the rest can be used for discharging ink from the pressure chamber. Thereby, it is possible to circulate ink between the inside and outside of the pressure chamber to remove bubbles and foreign matters accumulated in the pressure chamber.

  The plurality of communication passages included in the wall portion may be provided in positions opposite to each other with respect to the pressure chamber surrounded by the wall portion in a plane along the vibration plate and the nozzle plate. In this case, the ink in the pressure chamber easily flows in one direction passing through the plurality of communication paths, and the ink circulation efficiency is improved.

  Each wall part which comprises each pressure chamber may be provided in the said support substrate so that the said communicating path of each wall part may be located in a line along one direction. In this case, it is possible to circulate the ink so that it flows in series in each pressure chamber, or to circulate the ink so that it flows in parallel in each pressure chamber.

  The support substrate has an ink supply port for supplying ink from an ink containing part to the ink flow path, and an ink discharge port for discharging ink from the ink flow path to the ink containing part. In the support substrate, each wall portion constituting each pressure chamber is located between the ink supply port and the ink discharge port in a plane along the vibration plate and the nozzle plate, The ink supply port may be provided on one side of the one direction in which the communication paths are arranged, and the ink discharge port may be provided on the other side of the one direction.

  The ink supplied from the ink supply port to the ink flow path flows in series through the pressure chambers via the communication path and travels toward the ink discharge port. Therefore, ink can be efficiently circulated between the ink storage portion and each pressure chamber via the ink supply port and the ink discharge port.

  The support substrate includes: an ink supply port for supplying ink from an ink containing portion to the ink flow channel; an ink discharge port for discharging ink from the ink flow channel to the ink containing portion; A partition plate for partitioning the ink flow path on the outside, and in the support substrate, each wall portion constituting each pressure chamber is within the plane along the vibration plate and the nozzle plate, The ink supply port is located between the ink supply port and the ink discharge port, and the ink supply port is provided on one side in a direction perpendicular to the one direction in which the communication paths are arranged. The ink flow path is provided on the other side in a direction perpendicular to the one direction, and the ink flow path includes a first ink flow path communicating with one communication path of each wall portion by the partition plate, and the other The second ink flow path communicating with the communication path is processed. Is and said ink supply port is communicated with the first ink flow path, the ink discharge port may be in communication with the second ink channel.

  The ink supplied from the ink supply port to the first ink flow path flows in parallel through the pressure chambers via the communication path, and travels toward the ink discharge port via the second ink flow path. Accordingly, even with this configuration, it is possible to circulate ink between the ink storage portion and each pressure chamber via the ink supply port and the ink discharge port. In addition, since the first ink flow path and the second ink flow path are partitioned by a partition plate outside each wall portion, the first ink flow path and the second ink flow path are between the first ink flow path and the second ink flow path. The ink is always transferred through one of the pressure chambers (the ink can be transferred outside the pressure chamber). Thereby, all the ink supplied from the ink supply port can be used for the circulation of the ink in each pressure chamber.

  At least one of the plurality of communicating portions provided on the same wall portion may have the same depth as the substrate thickness of the support substrate. In this case, bubbles and foreign matters accumulated in the upper portion of the pressure chamber can be efficiently discharged through the communication path having the same depth as the substrate thickness of the support substrate.

  Of the plurality of communication paths provided on the same wall, the communication path located on the most downstream side in the direction in which ink flows from the ink supply port to the ink discharge port via the pressure chamber is the support It may have the same depth as the substrate thickness of the substrate. In this case, when the ink is circulated, the communication path located on the most downstream side is the communication path for discharging the ink, so that bubbles and foreign matter accumulated in the upper part of the pressure chamber can be efficiently and reliably removed through the communication path. Can be discharged.

  The hole may be a space. Even in this case, since the adjacent wall portions can be positioned apart from each other through the space (hole portion), the deformation of the diaphragm driving each pressure chamber is affected by the drive of the adjacent pressure chamber. Can be reliably suppressed.

  Each of the wall portions may have a shape (for example, a circle or a square) having the same aspect ratio in a plane along the diaphragm and the nozzle plate. In this case, the deformation shape of the diaphragm can be the same or substantially the same even in a plane perpendicular to the diaphragm, and the ink ejection characteristics can be made more uniform between the channels.

  Each of the wall portions may have a shape (for example, an ellipse, a rectangle, or a rhombus) having different aspect ratios in a plane along the diaphragm and the nozzle plate. In this case, the deformed shape of the diaphragm in the plane perpendicular to the diaphragm varies depending on how the plane perpendicular to the diaphragm is selected, but the deformed shape of the diaphragm in the plane perpendicular to the diaphragm There is no change in being symmetric. Therefore, even with such a configuration, it is possible to make the ink ejection characteristics uniform between the channels.

  In the support substrate, a plurality of groups having at least one row in which a plurality of wall portions are arranged in one direction are formed in parallel, and in adjacent groups, each wall portion is shifted by a predetermined pitch in the one direction. May be located. In this case, a higher-resolution image can be formed by arranging each wall portion and each pressure chamber at a high density. In particular, each group has a plurality of rows in which a plurality of wall portions are arranged in one direction in parallel, and adjacent wall portions in the same group are positioned at a predetermined pitch in the one direction. In this case, the pressure chambers are arranged with high density even in each group, and thus the above-described effect becomes higher.

  The driving element may include a piezoelectric thin film. In this case, the above-described effect can be obtained with a thin configuration of the drive element.

  The piezoelectric thin film may have a thickness of 1 μm to 10 μm. In this case, the above-described effects can be obtained with a configuration using a thin film piezoelectric body (piezoelectric thin film).

  The ink jet printer of the present embodiment includes the above-described ink jet head, and ejects ink from the ink jet head toward a recording medium. With this configuration, a high-quality and high-resolution image can be formed on a recording medium while being small in size and low in cost.

  The ink jet head of the present invention can be used in an ink jet printer.

1 Inkjet printer 8 Storage tank (ink storage part)
DESCRIPTION OF SYMBOLS 11 Support substrate 11a Pressure chamber 11b Wall part 11c Communication path 11c ₁ communication path 11c ₂ communication path 11d Ink supply port 11e Ink discharge port 12 Vibrating plate 13 Nozzle plate 13 Nozzle hole 14 Drive element 18 Hole 18a Ink channel 18a _1st 1 ink flow path 18a ₂ second ink flow path 21 inkjet head 22 partition plate 34 piezoelectric thin film

Claims (19)

An inkjet head that sandwiches a support substrate having a pressure chamber between a vibration plate and a nozzle plate and causes the vibration plate to vibrate by a drive element, thereby discharging ink in the pressure chamber to the outside through the nozzle holes of the nozzle plate. There,
The support substrate has a plurality of the pressure chambers, and has a wall portion surrounding each pressure chamber with a substantially constant thickness in a plane along the vibration plate and the nozzle plate,
The said wall part is an inkjet head provided with the same external shape independently for every said pressure chamber.   2. The inkjet head according to claim 1, wherein in the support substrate, a hole portion in which a part of the support substrate is removed is formed in at least a part of the periphery of the wall portion in the substrate thickness direction.   The inkjet head according to claim 2, wherein the hole constitutes an ink flow path for supplying ink to each pressure chamber.   The wall portion surrounding each pressure chamber in the support substrate has a communication path for communicating the pressure chamber surrounded by the wall portion and the ink flow path around the wall portion. The inkjet head as described.   The inkjet head according to claim 4, wherein a plurality of the communication passages are provided per one wall portion surrounding each pressure chamber.   The plurality of communication paths of the wall portion are provided at positions opposite to each other with respect to a pressure chamber surrounded by the wall portion, in a plane along the diaphragm and the nozzle plate. The inkjet head described in 1.   The inkjet head according to claim 6, wherein each wall portion constituting each pressure chamber is provided on the support substrate so that the communication path of each wall portion is aligned along one direction. The support substrate has an ink supply port for supplying ink from an ink containing part to the ink flow path, and an ink discharge port for discharging ink from the ink flow path to the ink containing part. ,
In the support substrate,
Each wall portion constituting each pressure chamber is located between the ink supply port and the ink discharge port in a plane along the vibration plate and the nozzle plate,
The ink supply port is provided on one side of the one direction in which the communication paths are arranged,
The ink jet head according to claim 7, wherein the ink discharge port is provided on the other side in the one direction. The support substrate includes: an ink supply port for supplying ink from an ink containing portion to the ink flow channel; an ink discharge port for discharging ink from the ink flow channel to the ink containing portion; A partition plate for partitioning the ink flow path on the outside;
In the support substrate,
Each wall portion constituting each pressure chamber is located between the ink supply port and the ink discharge port in a plane along the vibration plate and the nozzle plate,
The ink supply port is provided on one side in a direction perpendicular to the one direction in which the communication paths are arranged,
The ink discharge port is provided on the other side in a direction perpendicular to the one direction;
The ink flow path is partitioned by the partition plate into a first ink flow path communicating with one communication path of each wall and a second ink flow path communicating with the other communication path,
The ink supply port communicates with the first ink flow path;
The inkjet head according to claim 7, wherein the ink discharge port communicates with the second ink flow path.   The inkjet head according to claim 8 or 9, wherein at least one of the plurality of communicating portions provided on the same wall portion has the same depth as the substrate thickness of the support substrate.   Of the plurality of communication paths provided on the same wall, the communication path located on the most downstream side in the direction in which ink flows from the ink supply port to the ink discharge port via the pressure chamber is the support The inkjet head according to claim 8, which has the same depth as the substrate thickness of the substrate.   The inkjet head according to claim 2, wherein the hole is a space.   13. The inkjet head according to claim 1, wherein each of the walls has the same aspect ratio in a plane along the diaphragm and the nozzle plate.   13. The inkjet head according to claim 1, wherein each of the wall portions has a shape with a different aspect ratio in a plane along the vibration plate and the nozzle plate. In the support substrate,
A plurality of groups having at least one row in which a plurality of wall portions are arranged in one direction are formed in parallel,
The inkjet head according to claim 1, wherein in adjacent groups, each wall portion is located at a predetermined pitch in the one direction. Each group has a plurality of parallel rows with a plurality of walls arranged in one direction,
The inkjet head according to claim 15, wherein each wall portion is positioned with a predetermined pitch shifted in the one direction between adjacent rows in the same group.   The inkjet head according to claim 1, wherein the drive element includes a piezoelectric thin film.   The inkjet head according to claim 17, wherein the piezoelectric thin film has a thickness of 1 μm to 10 μm.   An inkjet printer comprising the inkjet head according to claim 1, wherein ink is ejected from the inkjet head toward a recording medium.

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