JP4622607B2 - Droplet discharge head and droplet discharge apparatus - Google Patents

Description

  The present invention relates to a droplet discharge head and a droplet discharge device, and more specifically, a droplet discharge head used for an inkjet recording head or the like that discharges ink droplets from a nozzle to perform printing on a recording medium, and inkjet recording. The present invention relates to a droplet discharge device used for an apparatus.

  Ink jet recording heads that use piezoelectric elements for ink ejection, especially in head configurations that use actuators that utilize the piezoelectric longitudinal or piezoelectric transverse effects of piezoelectric elements, in order to increase the deformation efficiency of the actuator, a part of the pressure chamber It is necessary to provide a portion with low rigidity. However, providing a low-rigidity portion in the pressure chamber is problematic because it reduces the efficiency of pressure generation.

  On the other hand, in order to achieve high resolution by printing with an ink jet recording head, it is necessary to narrow the nozzle pitch and arrange the nozzles in high density, for example, in a matrix, and accordingly, piezoelectric elements provided corresponding to each nozzle Is required to have a small and high-density structure.

Therefore, a pressure chamber is formed inside the laminated piezoelectric element, and the nozzle plate and the supply path plate are arranged opposite to each other with the piezoelectric element sandwiched in the laminating direction, so that a low rigidity portion is not provided in the pressure chamber. In both cases, there has been proposed a head configuration that can improve the pressure generation efficiency and can increase the density of the nozzle arrangement as compared with a conventional Kaiser-type piezoelectric element (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 7-81055

  However, in the above configuration, since the pressure chamber is formed by pulling out the stacked piezoelectric element in the stacking direction, both positive and negative electrodes are exposed in the pressure chamber. Therefore, it is necessary to completely seal this electrode portion, and further, processing such as a through hole and a groove is required in accordance with the electrode, which causes a manufacturing problem. In addition, it is necessary to provide an electrically inactive region between the piezoelectric elements provided corresponding to the respective nozzles, which becomes an obstacle in mounting the piezoelectric elements at a higher density. Further, when the piezoelectric element is compressed / expanded and deformed in the stacking direction, the deformation state of the end surface on the supply path plate side is not flat, and stress may be generated at the joint between the supply path plate and the piezoelectric element, leading to a failure. .

  In addition, in order to improve the pressure generation efficiency, the pressure chamber is made more than the pressure chamber is deformed in one direction (piezoelectric element stacking direction) and pressure (discharge energy) is applied to the ink as in the above configuration. It is desirable to deform in multiple directions and apply pressure to the ink on many faces in the pressure chamber.

  In view of the above-described facts, an object of the present invention is to provide a droplet discharge head capable of improving the generation efficiency of pressure generated to discharge droplets. It is another object of the present invention to provide a droplet discharge device that can achieve low power consumption by including the droplet discharge head.

In order to achieve the above object, according to the first aspect of the present invention, the pressure chamber to which the liquid is supplied from the liquid storage chamber via the supply path is divided into a plurality of directions by deformation of the piezoelectric longitudinal effect and the piezoelectric lateral effect of the piezoelectric element. By deforming, pressure is applied to the liquid in the pressure chamber to eject droplets from the nozzle connected to the pressure chamber, and the piezoelectric element is bonded to the piezoelectric element on the side opposite to the nozzle arrangement side. A movable inner wall surface that forms the pressure chamber and moves with deformation of the piezoelectric element is provided. The movable inner wall surface is formed by a supply path plate in which the supply path is formed, and the supply path plate includes a plurality of supply path plates. A plurality of the movable inner wall surfaces corresponding to the piezoelectric element are connected to each other, and the connecting portion is lower in rigidity than the supply path plate main body, and the connecting portion is a component part of the liquid storage chamber. It is characterized in that that.

  According to the first aspect of the present invention, the liquid supplied to the pressure chamber from the liquid storage chamber via the supply path is ejected as droplets from the nozzle. Therefore, the pressure chamber is deformed by deformation of the piezoelectric element, Apply pressure to the liquid. Here, since the piezoelectric element deforms the pressure chamber in a plurality of directions by the deformation of the piezoelectric longitudinal effect and the piezoelectric lateral effect, for example, compared to the case of deforming the pressure chamber only by the piezoelectric longitudinal effect or the deformation of only the piezoelectric lateral effect, Pressure generation efficiency is improved.

  According to a second aspect of the present invention, in the liquid droplet ejection head according to the first aspect, at least a part of the inner wall surface of the pressure chamber is formed by a deformed portion of the piezoelectric element.

  According to the second aspect of the present invention, since the deformation portion of the piezoelectric element that forms at least a part of the inner wall surface of the pressure chamber directly pressurizes the liquid in the pressure chamber, the loss of pressure applied to the liquid is reduced. The pressure generated by the deformation of the piezoelectric element is efficiently transmitted to the liquid.

When an additional note on the invention described in claim 1, the movable inner wall surface moves along with the deformation of the piezoelectric element is pressure / vacuum the liquid in the pressure chamber to the liquid droplet ejection direction (nozzle side). Thereby, the pressure chamber can be deformed in the droplet discharge direction, and the pressure generation efficiency can be improved.

Also, when an additional note about the invention of claim 1, the movable inner wall surface of the above, by forming the supply path plate supply path is formed, a dedicated plate or the like in order to form the movable inner wall Compared to the case, the droplet discharge head can be made smaller.

Further, regarding the invention according to claim 1 , the supply path plate is integrally formed by connecting a plurality of movable inner wall surfaces corresponding to the plurality of piezoelectric elements, for example, for high-speed driving of the piezoelectric elements. Accordingly, when the piezoelectric element and the movable inner wall surface vibrate, the vibration is attenuated by the connecting portion that connects the movable inner wall surfaces and has a lower rigidity than the supply plate main body. Thereby, the influence of the drive operation | movement between adjacent piezoelectric elements can be reduced.

  In addition, since this connecting portion is a constituent part that constitutes a part of the inner wall of the liquid storage chamber, the pressure generated in the pressure chamber for discharging droplets is absorbed by this connecting portion having low rigidity. The As a result, the pressure generated in the specific pressure chamber during droplet discharge is transmitted from the supply path to the liquid storage chamber, and the adverse effect on the pressure generation in the adjacent pressure chamber can be improved.

According to a third aspect of the present invention, in the droplet discharge head according to the first or second aspect , the piezoelectric element is formed in a cylindrical shape, and the pressure chamber is provided inside the cylindrical piezoelectric element. It is characterized by being.

In the third aspect of the present invention, the cylindrical piezoelectric element is deformed (compressed / expanded), for example, in the axial direction (droplet ejection direction) by the piezoelectric longitudinal effect, and, for example, the inner peripheral surface by the piezoelectric lateral effect. Is deformed inward / outward (reduced diameter / expanded diameter). Thereby, the liquid in the pressure chamber provided inside the piezoelectric element is pressurized by the entire inner peripheral surface of the piezoelectric element, and the pressure generation efficiency can be improved. Further, by making the piezoelectric element cylindrical, the piezoelectric elements (pressure chambers) and nozzles can be arranged with high density.

According to a fourth aspect of the present invention, in the liquid droplet ejection head according to the third aspect , the polarization direction of the piezoelectric element is the inside / outside direction of the piezoelectric element.

In the fourth aspect of the invention, in the cylindrical piezoelectric element, the piezoelectric longitudinal effect and the piezoelectric lateral effect of the piezoelectric element can be deformed by setting the polarization direction of the piezoelectric element to the inner and outer directions of the piezoelectric element.

According to a fifth aspect of the present invention, in the liquid droplet ejection head according to the third or fourth aspect, one of positive and negative electrodes for applying a drive signal to the piezoelectric element is on the inner peripheral surface of the piezoelectric element, and the other is It is provided on the outer peripheral surface of the piezoelectric element.

In the invention according to claim 5 , in the cylindrical piezoelectric element, one of positive and negative electrodes for applying a drive signal to the piezoelectric element is provided on the inner peripheral surface of the piezoelectric element, and the other is provided on the outer peripheral surface of the piezoelectric element. The polarization direction of the piezoelectric element can be the inside and outside directions of the piezoelectric element, and the piezoelectric longitudinal effect and the piezoelectric lateral effect of the piezoelectric element can be modified.

According to a sixth aspect of the present invention, in the liquid droplet ejection head according to any one of the first to fifth aspects, the liquid storage chamber, the supply path, the pressure chamber, the piezoelectric element, and the nozzle At least two of them are formed in different layers.

In the invention according to claim 6, when at least two or more of the respective parts provided in the droplet discharge head are arranged in different layers, for example, each part is formed by being divided into a plurality of constituent members (substrate or the like). A droplet discharge head can be manufactured by laminating a plurality of constituent members. This improves the manufacturability of the droplet discharge head.

According to a seventh aspect of the present invention, in the liquid droplet ejection head according to any one of the first to sixth aspects, the piezoelectric element substrate includes the piezoelectric element and the pressure chamber is provided inside the piezoelectric element. A nozzle plate in which the nozzles are formed, a communication path provided between the piezoelectric element substrate and the nozzle plate for communicating the pressure chamber and the nozzle, and supplying a drive signal to the piezoelectric element A wiring board on which a wiring pattern is formed, and the wiring pattern is formed between at least one of the piezoelectric element board and the wiring board and between the wiring board and the nozzle plate. It is characterized by having.

According to the seventh aspect of the present invention, a wiring having a communication path for communicating the pressure chamber and the nozzle and a wiring pattern for supplying a driving signal to the piezoelectric element is formed between the piezoelectric element substrate and the nozzle plate. By providing the substrate, the wiring pattern can be formed between the piezoelectric element substrate and the nozzle plate without hindering communication between the pressure chamber and the nozzle, and a drive signal can be supplied to the piezoelectric element. Further, by using such a wiring board, for example, even when nozzles and piezoelectric elements are arranged at high density, a drive signal supply path (wiring pattern) can be easily secured and formed.

According to an eighth aspect of the present invention, in the liquid droplet ejection head according to the seventh aspect , the nozzle plate and the wiring board are integrated.

In the invention according to claim 8 , by integrally forming the nozzle plate and the wiring board, the step of joining the nozzle plate and the wiring board can be omitted, and the manufacturability of the droplet discharge head is improved.

According to a ninth aspect of the present invention, in the droplet discharge head according to the seventh or eighth aspect , a drive element for transmitting the drive signal is formed in the vicinity of the nozzle in the wiring board. It is said.

In the invention according to claim 9 , since the driving element can be formed together with the wiring pattern in the manufacturing process of the wiring board, for example, the process of mounting the driving package IC or the like on the wiring board becomes unnecessary, and the manufacturability Will improve. In addition, since the drive element that generates heat as the piezoelectric element is driven is cooled by the flow of ink ejected from the nozzles, malfunction of the drive element due to temperature rise and heating of the droplet discharge recording head can be suppressed. .

According to a tenth aspect of the present invention, in the liquid droplet ejection head according to any one of the seventh to ninth aspects, the wiring pattern is formed between the piezoelectric element substrate and the wiring substrate to cover them. In addition, a part of the wiring pattern is exposed in the pressure chamber.

In the invention according to claim 10 , for example, when an IC (heat generating component) for driving a piezoelectric element mounted on the wiring board generates heat, the heat is conducted through the wiring pattern and is dissipated by the liquid in the pressure chamber. Therefore, the cooling effect of the heat generating component is enhanced.

According to an eleventh aspect of the present invention, in the liquid droplet ejection head according to the tenth aspect, one of the positive and negative electrodes provided on the inner peripheral surface of the piezoelectric element and the wiring pattern exposed in the pressure chamber. A contact portion that is electrically connected to a part is arranged in the pressure chamber.

In the invention according to claim 11 , as in the invention according to claim 10 , while making electrical connection between one of the positive and negative electrodes provided on the inner peripheral surface of the piezoelectric element and the wiring pattern by the contact portion, A high cooling effect for the heat-generating component can be obtained.

According to a twelfth aspect of the present invention, in the droplet discharge head according to the eleventh aspect , one of the positive and negative electrodes and the contact portion are covered with a low water-permeable insulating film.

According to the twelfth aspect of the present invention, since the electrode and the contact portion are protected from the liquid by the low water permeable film, disconnection due to corrosion of the electrode and the contact portion can be prevented.

A thirteenth aspect of the invention is characterized by including the droplet discharge head according to any one of the first to twelfth aspects.

In the invention according to claim 13 , it is possible to reduce the power consumption of the droplet discharge device by providing the droplet discharge head capable of improving the generation efficiency of the pressure generated for discharging the droplet. it can.

  Since the droplet discharge head of the present invention has the above-described configuration, it is possible to improve the generation efficiency of the pressure generated for discharging the droplet. In addition, the liquid droplet ejection apparatus of the present invention can achieve low power consumption by including the liquid droplet ejection head.

  Hereinafter, an ink jet recording head and an ink jet recording apparatus according to embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
First, the outline of the inkjet recording apparatus 100 will be described with reference to FIG. The recording medium will be described as recording paper P. In FIG. 1, the conveyance direction of the recording paper P in the inkjet recording apparatus 100 is represented by an arrow S as a sub-scanning direction, and the direction orthogonal to the conveyance direction is represented by an arrow M as a main scanning direction.

  As shown in FIG. 1, the ink jet recording apparatus 100 according to the present embodiment includes a carriage 112 on which black, yellow, magenta, and cyan ink jet recording units 130 (ink jet recording heads 10) are mounted. The carriage 112 has a pair of brackets 114 protruding from the upstream side in the conveyance direction of the recording paper P (only one bracket 114 is shown in the figure), and circular holes formed in the pair of brackets 114 respectively. The shaft 120 installed in the main scanning direction is inserted.

  A driving pulley (not shown) and a driven pulley (not shown) constituting the main scanning mechanism 116 are disposed on both ends in the main scanning direction with respect to the carriage 112. A part of a timing belt 122 that is wound around these driving pulleys and driven pulleys and travels in the main scanning direction is fixed to the carriage 112. Accordingly, when the timing belt 122 travels in the main scanning direction by the rotational driving of the driving pulley, the carriage 112 is reciprocated in the main scanning direction by the pair of brackets 114 being guided by the shaft 120.

  A paper feed tray 126 for storing recording paper P before image printing in a bundle is provided at the lower front side of the inkjet recording apparatus 100. Above the paper feed tray 126, a paper discharge tray 128 for discharging the recording paper P on which an image has been printed by the ink jet recording unit 130 for each color is provided. Also, below the carriage 112 and the shaft 120, there is a sub-scanning mechanism 118 composed of a transport roller and a discharge roller for transporting the recording paper P fed one by one from the paper feed tray 126 at a predetermined pitch in the sub-scanning direction. Is provided.

  In addition, the inkjet recording apparatus 100 is provided with a control panel 124 for performing various settings during printing, a maintenance station (not shown), and the like. The maintenance station includes a cap member, a suction pump, a dummy jet receiver, a cleaning mechanism, and the like, and performs maintenance operations such as a suction recovery operation, a dummy jet operation, and a cleaning operation.

  Each color ink jet recording unit 130 is configured by integrally forming the ink jet recording head 10 shown in FIGS. 2 and 3 and an ink tank (not shown) for supplying ink to the ink jet recording head 10. A plurality of nozzles 22 (see FIG. 3) formed on the lower surface (ink ejection surface) of the recording medium P are mounted on the carriage 112 so as to face the recording paper P. As a result, the ink jet recording head 10 selectively ejects ink droplets from the nozzles 22 on the recording paper P while moving in the main scanning direction by the main scanning mechanism 116, thereby image data for a predetermined band region. A part of the image based on is recorded.

  When one movement in the main scanning direction is completed, the recording paper P is conveyed by a predetermined pitch in the sub scanning direction by the sub scanning mechanism 118, and the ink jet recording head 10 (ink jet recording unit 130) is again moved in the main scanning direction ( A part of the image based on the image data is recorded in the next band area while moving in the opposite direction). By repeating such an operation a plurality of times, the recording paper P The entire image based on the image data is recorded in full color.

  The ink jet recording apparatus 100 is configured as described above. Next, the ink jet recording head 10 mounted on the ink jet recording apparatus 100 will be described in detail.

  The ink jet recording head 10 of the present embodiment shown in FIGS. 2 to 4 includes a nozzle plate 12, a printed wiring board 14, a piezoelectric element substrate (actuator plate) 16, a supply path plate 18, and an ink pool plate from the lower side of the figure. The members are laminated in the order of 20, and each member is joined to each other.

  As shown in FIG. 4, the nozzle plate 12 is formed with a plurality of nozzles 22 each having a circular through hole, and these nozzles 22 are arranged in a matrix at predetermined intervals.

  In the printed wiring board 14, communication paths 24 each having a circular through hole having a diameter slightly larger than the nozzle diameter are formed at positions corresponding to the nozzles 22 of the nozzle plate 12 (FIG. 3B and FIG. 3). 6 (B)). An annular contact electrode 26 is formed on the upper surface of the printed wiring board 14 at a position corresponding to each communication path 24, and each contact electrode 26 is connected via a wiring pattern 28 formed on the upper surface of the substrate. The drive IC 30 mounted in the vicinity of the end of the upper surface of the substrate is electrically connected. The drive IC 30 receives a control signal (printing command) from the outside (head control unit) through a contact portion 31 formed on the printed wiring board 14, and a piezoelectric element described below based on the control signal. An electric signal (drive signal) is transmitted to each piezoelectric element 32 on the substrate 16 to drive each piezoelectric element 32 at a predetermined timing.

  As shown in FIG. 5, the piezoelectric element substrate 16 includes a plurality of piezoelectric elements 32 that are individually driven by the drive IC 30. These piezoelectric elements 32 have a cylindrical shape penetrating along the thickness direction of the piezoelectric element substrate 16 and have an inner diameter slightly larger than the communication path 24 (FIGS. 3B and 6B). reference). The piezoelectric elements 32 are arranged in a matrix corresponding to the nozzles 22 and the communication paths 24, and the lower ends thereof are integrated with the thin base substrate portion 33.

  6A and 6B, a positive electrode 34 is formed on the outer peripheral surface of the piezoelectric element 32 so as to cover the entire outer peripheral surface. The electrodes 34 of each piezoelectric element 32 are electrically connected to each other via a common electrode 36 formed on the upper surface of the base substrate 33, and the common electrode 36 is electrically connected to the drive IC 30 via a wiring pattern (not shown). Connected. Further, a negative electrode 38 is formed on the inner peripheral surface of the piezoelectric element 32 so as to cover the entire inner peripheral surface, and each electrode 38 of each piezoelectric element 32 has a lower end on each of the printed circuit boards 14. The contact electrode 26 is brought into contact with and electrically connected.

  Thus, in this cylindrical piezoelectric element 32, the positive electrode (electrode 38) is provided on the outer peripheral surface and the negative electrode (electrode 34) is provided on the inner peripheral surface, so that the polarization direction is the inner / outer direction of the piezoelectric element 32. Specifically, the piezoelectric element 32 is configured to be directed from the outside toward the inside. The positive and negative electrodes can be arranged oppositely inside and outside the piezoelectric element 32. The piezoelectric element 32 is configured as a so-called wall-type piezoelectric element by having a structure in which a side surface (outer surface) in the polarization direction is connected to a wall portion (base substrate portion 33). Thus, when an electrical signal from the driving IC 30 is applied to the piezoelectric element 32 disposed between the electrodes 34 and 38, the piezoelectric element 32 performs a predetermined deformation operation described later.

  In the supply path plate 18, supply paths 40 each having a circular through hole slightly smaller than the inner diameter of the piezoelectric element 32 are formed at positions corresponding to the piezoelectric elements 32 of the piezoelectric element substrate 16 (FIG. 3 ( B) and FIG. 6B). At a position corresponding to each piezoelectric element 32 on the lower surface of the supply path plate 18, there is a protruding part (thick part) 42 that protrudes in a circular shape having the same diameter as the outer diameter of the piezoelectric element 32 around the supply path 40. These protrusions 42 are provided, and the protrusions 42 are firmly joined to the piezoelectric elements 32. Further, the protruding portions 42 are connected to each other, and the connecting portions (around the protruding portions 42) are thinner than the supply path plate main body and the protruding portions 42. A low-rigidity damper portion 44 is formed by the connecting portions. Has been.

  When the supply path plate 18 is laminated on the piezoelectric element substrate 16, a pressure chamber 46 is formed inside the cylindrical piezoelectric element 32, as shown in FIGS. 6A and 6B. In the pressure chamber 46, the upper wall surface 46 </ b> A is formed by the lower surface (movable inner wall surface) of the projecting portion 42, and the inner wall surface 46 </ b> B having a peripheral surface shape is the inner peripheral surface ( It is formed by the deformation part.

  As shown in FIGS. 3A and 6A, the ink pool plate 20 has a cavity formed on the lower surface side, and an ink inlet (ink supply path) communicating with the cavity on the upper surface. ) 48 is provided. When the ink pool plate 20 is stacked on the supply path plate 18, an ink pool 50 is formed between the ink path plate 18 and the supply path plate 18. Further, the damper portion 44 of the supply path plate 18 is a constituent part constituting a part of the inner wall of the ink pool 50, and ink is passed through the ink inlet 48 from the outside (ink tank) to the ink pool 50. Supplied and stored.

  The ink jet recording head 10 of the present embodiment has the above-described configuration. In the ink jet recording head 10, as described above, each part from the nozzle 22 to the ink pool 50 (nozzle 22, communication path 24, pressure chamber 46 ( The piezoelectric element 32), the supply path 40, and the ink pool 50) are arranged in layers by the respective constituent members.

  Next, the printing (ink ejection) operation and action by the above-described inkjet recording head 10 of the present embodiment will be described.

  In printing by the ink jet recording head 10, first, ink stored in the ink pool 50 is supplied to the pressure chamber 46 through the supply path 40, and further filled from the pressure chamber 46 to the nozzle 22 through the communication path 24.

  Here, when an electrical signal is not applied between the electrodes 34 and 38, the piezoelectric element 32 is maintained in a cylindrical shape as shown in FIG. 7A. Further, when an electrical signal is applied between the electrodes 34 and 38 by a print command, the piezoelectric element 32 is charged and deformed so as to expand in a barrel shape when viewed in the axial cross section as shown in FIG. 7B. To do.

  In the piezoelectric element 32 of the present embodiment, as shown in FIG. 7C, the diameter indicated by the arrow d33 is caused by the piezoelectric longitudinal effect (d33) that applies an electric signal in the polarization direction and causes distortion in the parallel direction. The piezoelectric transverse effect (d31) that expands and deforms in the direction, adds an electric signal in the polarization direction, and generates distortion in the direction perpendicular thereto, compresses and deforms in the axial direction indicated by the arrow d31 (a), and moves to the arrow d31 ( It contracts and deforms in the circumferential direction shown in b). Thus, the cylindrical piezoelectric element 32 is deformed in three directions: a radial direction due to the piezoelectric longitudinal effect, an axial direction due to the piezoelectric lateral effect, and a circumferential direction.

  Here, due to the compressive deformation in the axial direction due to the piezoelectric lateral effect of the piezoelectric element 32, the protrusion 42 of the supply path plate 18 joined to the upper end surface of the piezoelectric element 32, that is, the upper wall surface 46A of the pressure chamber 46 is on the nozzle 22 side. (Arrow A in FIG. 7B), and the ink in the pressure chamber 46 is pressurized and compressed. Further, the expansion deformation in the radial direction due to the piezoelectric longitudinal effect of the piezoelectric element 32 and the contraction deformation in the circumferential direction due to the piezoelectric lateral effect are combined, and the inner peripheral surface (deformation portion) of the piezoelectric element 32, that is, the pressure chamber 46. The inner wall surface 46B bulges inward (arrow B in FIG. 7B), and pressurizes and compresses the ink in the pressure chamber 46. The ink in the pressure chamber 46 pressurized by the deformation of the pressure chamber 46 in the two directions by these two deformation operations is ejected from the nozzle 22 as an ink droplet through the communication path 24.

  Subsequently, when the application of the electric signal between the electrodes 34 and 38 is stopped and the electric charge accumulated in the piezoelectric element 32 is discharged, the piezoelectric element 32 is shown in FIG. 7 (A) from the state of FIG. 7 (B). Return to the original cylindrical shape. Along with this, due to the return force of the meniscus formed in the nozzle 22, the ejected ink is replenished from the ink pool 50 into the pressure chamber 46 through the supply path 40.

  By repeating this ink ejection operation, ink droplets are continuously ejected from the nozzles 22 of the inkjet recording head 10 and printed on paper or the like.

  As described above, in the inkjet recording head 10 of the present embodiment, the ink supplied from the ink pool 50 to the pressure chamber 46 via the supply path 40 is ejected from the nozzle 22 as ink droplets. The pressure chamber 46 is deformed by deformation, and pressure is applied to the ink in the pressure chamber 46. This piezoelectric element 32 deforms the pressure chamber 46 in two directions by deformation of the piezoelectric longitudinal effect and the piezoelectric transverse effect. For example, the pressure generation efficiency is improved as compared with the case where the pressure chamber is deformed by deformation of only the piezoelectric longitudinal effect or only the piezoelectric lateral effect.

  In this embodiment, the inner peripheral surface, which is a deformed portion of the piezoelectric element 32 that forms the inner wall surface 46B of the pressure chamber 46, directly pressurizes the ink in the pressure chamber 46, so that the pressure applied to the ink is reduced. The loss is reduced, and the pressure generated by the deformation of the piezoelectric element 32 is efficiently transmitted to the ink.

  In the present embodiment, the upper wall surface 46A of the pressure chamber 46 moves in accordance with the deformation of the piezoelectric element 32, and the ink in the pressure chamber 46 is pressurized / depressurized in the ejection direction (nozzle 22 side). Thereby, the pressure chamber 46 can be deformed in the ink discharge direction, and the pressure generation efficiency can be improved. Further, the upper wall surface 46A (movable inner wall surface) of the pressure chamber 46 having the movable structure is formed by the supply path plate 18 (projecting portion 42), so that a dedicated inner wall surface is formed to form such a movable inner wall surface. Compared with the case where a plate or the like is provided, the inkjet recording head 10 can be configured in a small size.

  Further, in the present embodiment, the piezoelectric element 32 is formed in a cylindrical shape and the pressure chamber 46 is provided therein, so that the ink in the pressure chamber 46 is transferred to the entire inner peripheral surface of the piezoelectric element 32 (the pressure chamber 46). The inner wall surface 46B) is pressurized and the pressure generation efficiency can be improved. Furthermore, with such a cylindrical piezoelectric element 32, the piezoelectric elements 32 (pressure chambers 46) and the nozzles 22 can be arranged with high density, so that it is possible to achieve high resolution of the printed image.

  In the present embodiment, the piezoelectric element 32 is driven at a high speed by the above-described ink ejection operation. When the piezoelectric element 32 and the upper wall surface 46A (the protruding portion 42) of the pressure chamber 46 vibrate due to the high speed driving, The vibration is attenuated by the damper portion 44 that connects the protruding portions 42 and has a lower rigidity than the supply plate main body. Thereby, the influence (crosstalk) of the driving operation between the adjacent piezoelectric elements 32 can be reduced.

  Further, since the damper portion 44 is a constituent part that constitutes a part of the inner wall of the ink pool 50, the pressure generated in the pressure chamber 46 for ejecting ink droplets is absorbed by the damper portion 44. Thereby, the pressure generated in the specific pressure chamber 46 when ink droplets are ejected is transmitted from the supply path 40 to the ink pool 50, and the adverse effect on the pressure generation in the adjacent pressure chamber 46 can be improved. Accordingly, the ink ejection performance is stabilized.

  Further, in this embodiment, each part (nozzle 22, communication path 24, pressure chamber 46 (piezoelectric element 32), supply path 40, and ink pool 50) provided in the inkjet recording head 10 is arranged in different layers. In addition, the ink jet recording head 10 can be manufactured by forming each of these parts into a plurality of constituent members and stacking the constituent members. Thereby, the manufacturability of the inkjet recording head 10 is improved.

  Further, in the ink jet recording apparatus 100 of this embodiment, the power consumption can be reduced by providing the ink jet recording head 10 described above.

(Second Embodiment)
The second embodiment is a modification of the piezoelectric element substrate used in the above-described ink jet recording head 10.

  As shown in FIG. 8A, in the piezoelectric element substrate 60 of the present embodiment, a plurality of provided piezoelectric elements 62 are formed in a square cylinder shape. Similarly to the first embodiment, the piezoelectric elements 62 are also arranged in a matrix corresponding to the nozzles 22 of the nozzle plate 12, and the lower end portion is connected to the thin base substrate portion 63 and integrated. ing. 8B, the positive electrode 34 is formed on the outer peripheral surface of the piezoelectric element 62 so as to cover the entire outer peripheral surface, and the negative electrode is provided on the inner peripheral surface. 38 is formed so as to cover the entire inner peripheral surface, and the polarization direction is configured to be the inner and outer directions of the piezoelectric element 62 (the direction from the outer side to the inner side).

  When an electrical signal is applied between the electrodes 34 and 38, the piezoelectric element 62 is also expanded and deformed in the inner and outer directions indicated by the arrow d33 by the piezoelectric longitudinal effect (d33) as shown in FIG. 8B. Further, due to the piezoelectric lateral effect (d31), it is compressed and deformed in the axial direction indicated by the arrow d31 (a), and contracted and deformed in the side direction indicated by the arrow d31 (b). It is deformed in the directions of arrows A and B shown in FIG.

  Therefore, even in the case of such a square cylindrical piezoelectric element 62, the deformations of the piezoelectric longitudinal effect and the piezoelectric transverse effect are combined, and the pressure generation efficiency can be improved.

  In addition, in the case of such a square cylindrical shape, when forming a plurality of piezoelectric elements on a single substrate using etching or the like, it is easier to form individual piezoelectric elements than in a cylindrical shape, And it can arrange | position with a narrower space | interval. Thus, as in the first and second embodiments, when a plurality of piezoelectric elements are arranged in a matrix, a rectangular cylindrical piezoelectric element is more efficient than a cylindrical one without causing unnecessary space. The nozzles can be arranged at high density, and the nozzle density can be further increased.

(Third embodiment)
The third embodiment is a modification in which the configuration of the printed wiring board is changed in the ink jet recording head 10 described in the first embodiment.

  As shown in FIG. 9, the ink jet recording head 70 of this embodiment is similar to the first embodiment in that the nozzle plate 12, the printed wiring board 72, the piezoelectric element substrate 16, the supply path plate 18, and the ink pool plate. 20 is laminated.

  Here, as shown in FIG. 10, a plurality of driving elements (IC chips) 74 that transmit electric signals for driving the piezoelectric elements 32 are formed on the upper surface of the printed wiring board 72 of the present embodiment. Yes. These drive elements 74 are formed together with a wiring pattern or the like in the manufacturing process of the printed wiring board 72, and in the vicinity of each communication path 24 formed corresponding to each nozzle 22 of the nozzle plate 12, that is, each The electrodes are arranged in the vicinity of the nozzles 22 and are electrically connected to the contact electrodes 26 via wiring patterns formed on the substrate. In addition, when a control signal is input from the outside through the contact portion 76 formed on the upper surface end portion of the printed wiring board 72, these driving elements 74 are also connected to the piezoelectric elements of the piezoelectric element substrate 16 based on the control signal. An electric signal is output to 32 and each piezoelectric element 32 is driven.

  The ink jet recording head 70 of the present embodiment is configured as described above, and in this ink jet recording head 70, the process of mounting the driving IC 30 as described in the first embodiment on the printed wiring board is not necessary. , Productivity is improved. In addition, since the drive element 74 that generates heat as the piezoelectric element 32 is driven is cooled by the flow of ink ejected from the nozzles 22, the drive element 74 malfunctions due to temperature rise and the inkjet recording head 70 is heated (heated). Stress). Furthermore, since the wiring pattern (electrical wiring) can be wired at a low density in a portion (exposed portion) that is not covered with the piezoelectric element substrate 16 on the printed wiring board 72, it is compared with the configuration of the first embodiment. , Electrical reliability can be improved.

(Fourth embodiment)
The fourth embodiment is a modification in which the configuration of the wiring pattern and the like is changed in the inkjet recording head 10 described in the first embodiment.

  As shown in FIG. 11, the inkjet recording head 80 of the present embodiment has a wiring pattern (contact electrode) 84 formed on the upper surface (between the piezoelectric element substrate 16 and the printed wiring board 82) on the printed wiring board 82. While being covered with the element substrate 16, a part thereof is exposed from the lower end portion of the piezoelectric element 32 to the pressure chamber 46 (communication path 24) side. The exposed portion is a contact portion 86 that is electrically connected to the electrode 38 formed on the inner peripheral surface of the piezoelectric element 32. The electrode 38 here is further extended downward from the contact portion 86 and is formed so as to cover the inner periphery of the communication path 24. Further, a low water permeable film 88 is formed on the surface of the electrode 38 including the contact portion 86, and the electrode 38 and the contact portion 86 are covered with the low water permeable film 88.

  Thereby, in the inkjet recording head 80 of this embodiment, when the electrode 38 is provided on the inner peripheral surface of the piezoelectric element 32, the electrode 38 and the wiring pattern 84 can be electrically connected. Further, when the driving IC 30 generates heat, the heat is conducted through the wiring pattern 84 and is radiated by the ink flowing from the pressure chamber 46 to the communication path 24, so that the cooling effect of the driving IC 30 is enhanced. Further, since the electrode 38 and the contact portion 86 are protected from the ink by the low water permeable film 88, the electrolysis of the ink and the disconnection due to the corrosion of the electrode 38 and the contact portion 86 can be prevented, and the reliability is improved. can do.

(Fifth embodiment)
The fifth embodiment is a modification in which the configuration of the wiring pattern is further changed in the inkjet recording head 80 according to the fourth embodiment described above.

  As shown in FIG. 12, in the ink jet recording head 90 of this embodiment, no wiring pattern is formed on the upper surface of the printed wiring board 92, and the wiring pattern 94 is formed on the lower surface of the printed wiring board 92, that is, the nozzle plate. 12 and the printed wiring board 92. The lower end portion of the electrode 38 that extends from the inner peripheral surface of the piezoelectric element 32 to the inner peripheral surface of the communication path 24 is a contact portion 96 with the wiring pattern 94. Also in this embodiment, the low water-permeable film 88 is formed on the surface of the electrode 38 including the contact part 96, and the electrode 38 and the contact part 96 are covered with the low water-permeable film 88.

  As described above, when the wiring pattern 94 is formed between the nozzle plate 12 and the printed wiring board 92, a print in which a large number of piezoelectric elements 32, contact electrodes 26, and the like are arranged as in the first to fourth embodiments. Compared with the case where a wiring pattern is formed on the upper surface side of the wiring substrate 92 (between the piezoelectric element substrate 16 and the printed wiring substrate 92), the wiring area of the pattern and the degree of freedom of wiring are improved. As a result, many wiring patterns can be easily formed, and the nozzles can be further densified. Also in this embodiment, since the electrode 38 and the contact portion 86 are protected from ink by the low water permeable film 88, the reliability is improved.

  As mentioned above, although the present invention was explained in detail by the 1st-5th embodiment mentioned above, the present invention is not limited to those embodiments, and other various forms are within the scope of the present invention. It can be implemented.

  For example, in the embodiment described above, the nozzle plate 12 and the printed wiring boards 14, 72, 82, and 92 are separated from each other, but they can also be integrated. In that case, the process of joining the nozzle plate and the printed wiring board can be omitted, and the productivity of the ink jet recording head is improved.

  The present invention is not limited to the above-described ink jet recording head and ink jet recording apparatus, and other liquid droplet ejection heads and liquid droplet ejections used in pattern forming apparatuses that eject liquid droplets for pattern formation of semiconductors and the like. It can also be applied to devices.

1 is a perspective view showing an appearance of an ink jet recording head according to a first embodiment of the present invention. 1 is a perspective view showing an appearance of an ink jet recording head according to a first embodiment of the present invention. FIG. 3A is a perspective view showing the external appearance and internal structure of the ink jet recording head of FIG. 2 with a partial break, and FIG. 3B is an enlarged perspective view of a 3B portion of FIG. FIG. 3 is an exploded perspective view showing an exploded state of the ink jet recording head of FIG. 2. 1 is a perspective view showing an appearance of a piezoelectric element substrate according to a first embodiment of the present invention. 2A and 2B are cross-sectional views of the inkjet recording head of FIG. 2, in which FIG. 3A is a cross-sectional view taken along line 6A-6A in FIG. 3A, and FIG. (A) is sectional drawing which shows the undeformed state of the piezoelectric element and pressure chamber which concern on the 1st Embodiment of this invention, (B) is sectional drawing which shows a deformation | transformation state, (C) shows the deformation | transformation direction of a piezoelectric element. It is an expansion perspective view. (A) is a perspective view which shows the external appearance of the piezoelectric element board | substrate which concerns on the 2nd Embodiment of this invention, (B) is an expanded perspective view which shows the deformation | transformation direction of a piezoelectric element. It is a perspective view which shows the external appearance of the inkjet recording head which concerns on the 3rd Embodiment of this invention. It is a disassembled perspective view which shows the decomposition | disassembly state of the inkjet recording head of FIG. It is sectional drawing which shows the piezoelectric element vicinity of the inkjet recording head which concerns on the 4th Embodiment of this invention. It is sectional drawing which shows the piezoelectric element vicinity of the inkjet recording head which concerns on the 5th Embodiment of this invention.

Explanation of symbols

10 Inkjet recording head (droplet ejection head)
12 Nozzle Plate 14 Printed Wiring Board 16 Piezoelectric Element Board 18 Supply Path Plate 20 Ink Pool Plate 22 Nozzle 24 Communication Path 28 Wiring Pattern 32 Piezoelectric Element 34 Electrode 38 Electrode 40 Supply Path 42 Protrusion 44 Damper 46 Pressure Chamber 46A Upper Wall 46B Inner wall surface 50 Ink pool 60 Piezoelectric element substrate 62 Piezoelectric element 70 Inkjet recording head 72 Printed wiring board 74 Drive element 76 Contact portion 80 Inkjet recording head 82 Printed wiring substrate 84 Wiring pattern 86 Contact portion 88 Low water-permeable film 90 Inkjet recording head 92 Printed wiring board 94 Wiring pattern 96 Contact portion 100 Inkjet recording apparatus (droplet discharge apparatus)

Claims (13)

The pressure chamber in which the liquid is supplied from the liquid storage chamber via the supply path is deformed in a plurality of directions by deformation of the piezoelectric longitudinal effect and the piezoelectric lateral effect of the piezoelectric element, so that pressure is applied to the liquid in the pressure chamber. A droplet is ejected from a nozzle communicating with the chamber, and the pressure chamber is formed on the opposite side of the piezoelectric element from the nozzle arrangement side to form the pressure chamber and moves in accordance with the deformation of the piezoelectric element. A movable inner wall is provided,
The movable inner wall surface is formed by a supply path plate in which the supply path is formed,
In the supply path plate, the plurality of movable inner wall surfaces corresponding to the plurality of piezoelectric elements are connected to each other, and the connection part is lower in rigidity than the supply path plate body, and the connection part is the liquid A droplet discharge head, which is a constituent part of a storage chamber .   The droplet discharge head according to claim 1, wherein at least a part of an inner wall surface of the pressure chamber is formed by a deforming portion of the piezoelectric element. Wherein the piezoelectric element is formed in a cylindrical shape, according to claim 1 or claim 2, wherein the droplet discharge head, characterized in that the pressure chamber inside the cylindrical piezoelectric element is provided. 4. The liquid droplet ejection head according to claim 3, wherein the polarization direction of the piezoelectric element is set to the inside / outside direction of the piezoelectric element. The one of the positive and negative electrodes for applying a driving signal to the piezoelectric element to the inner peripheral surface of the piezoelectric element and the other of claims 3 or claim 4 further characterized in that provided on the outer peripheral surface of the piezoelectric element Droplet discharge head. The liquid storage chamber, the supply passage, the pressure chamber, the piezoelectric element, and any one of claims 1 to 5, characterized in that at least two of said nozzles are arranged in different layers 2. A droplet discharge head according to item 1. A piezoelectric element substrate provided with the piezoelectric element and provided with the pressure chamber inside the piezoelectric element;
A nozzle plate on which the nozzles are formed;
A wiring board provided between the piezoelectric element substrate and the nozzle plate, in which a communication path for communicating the pressure chamber and the nozzle, and a wiring pattern for supplying a driving signal to the piezoelectric element; ,
Have
The wiring pattern, between the wiring substrate and the piezoelectric element substrate, and, any one of claims 1 to 6, characterized in that it is formed in at least one of between the nozzle plate and the circuit board 2. A droplet discharge head according to item 1. 8. The liquid droplet ejection head according to claim 7, wherein the nozzle plate and the wiring board are integrated. Wherein in the vicinity of the nozzle in the wiring board, according to claim 7 or claim 8 the liquid droplet ejection head, wherein a driving element for transmitting the drive signal is formed. With covered thereto are formed between the wiring board the wiring pattern and the piezoelectric element substrate according to claim 7 to claim a part of the wiring pattern, characterized in that it is exposed to the pressure chamber 10. The droplet discharge head according to any one of items 9 . A contact portion that electrically connects one of the positive and negative electrodes provided on the inner peripheral surface of the piezoelectric element and a part of the wiring pattern exposed in the pressure chamber is disposed in the pressure chamber. The droplet discharge head according to claim 10 . The droplet discharge head according to claim 11 , wherein one of the positive and negative electrodes and the contact portion are covered with a low water-permeable insulating film. Droplet discharge apparatus comprising: a liquid droplet ejecting head according to any one of claims 1 to 12.

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