JP2005288916A - Discharging head and manufacturing method of discharging head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharging head and its manufacturing method which prevent the warpage of a piezoelectric element at the time of baking from occurring while being able to manufacture the piezoelectric element of sheet-like easily. <P>SOLUTION: At the internal part of a piezoelectric element substrate 55 formed by laminating a piezoelectric material and electrode material by turns, a low-rigidity part 59 consisting of a hollow part is provided at the opposite side of a pressure chamber 52 of a piezoelectric active part 58 composed of a single-layer piezoelectric element. While securing the easiness of handling for manufacturing by making the thickness of the piezoelectric element substrate 55 increased, the sheet-like piezoelectric active part 58 can be formed. If a second low-rigidity part which has nearly the same shape and size as the ones of the low-rigidity part 59 is provided at the position symmetrical to the face dividing the thickness direction of the low-rigidity part 59 and the piezoelectric element substrate 55 into nearly two parts in the internal part of the piezoelectric element substrate 55, the curve at the time of baking the piezoelectric element substrate 55 can be prevented from occurring. For the low-rigidity part 59, a member with the rigidity lower than the one of the piezoelectric element may be used instead of the hollow part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ejection head and an ejection head manufacturing method, and more particularly, to an ejection head structure having a thin plate laminated structure and a manufacturing technique thereof.

  In recent years, inkjet printers have become widespread as data output devices for images and documents. An ink jet printer can drive recording elements such as nozzles provided in a recording head according to data, and can form data on a printing medium (recording medium) such as recording paper by ink ejected from the nozzles. .

  In an ink jet printer, a desired image is formed on a print medium by relatively moving a print head having a large number of nozzles and the print medium and ejecting ink droplets from the nozzles.

  In a method of ejecting ink from a print head provided in an ink jet recording apparatus, an actuator such as a piezoelectric element is provided on a vibration plate forming a wall surface of a pressure chamber in which ink is stored, and the pressure is obtained by driving the actuator. The ink in the pressure chamber is heated by a method in which the chamber is deformed and the amount of ink corresponding to the amount of change in the pressure chamber volume is discharged, or by a heater provided in the pressure chamber. There is a bubble jet method in which ink is ejected in accordance with pressure.

  A print head using a method of ejecting ink by deformation of a piezoelectric element includes a nozzle plate on which nozzles for ejecting ink droplets are formed, a channel plate on which pressure chambers and ink channels are formed, a vibration plate, a piezoelectric element, and the like Is formed in a thin plate shape, and has a laminated structure in which these thin plate-like members are laminated by bonding with an adhesive or the like.

  In the case of forming the piezoelectric element, a bulk material or a green sheet is laminated and pressed, and then fired, and then processed into a desired thickness by polishing or the like. Furthermore, an individual electrode and a common electrode are attached to complete the piezoelectric element. The piezoelectric body formed in this way is joined to the diaphragm, and the pressure chamber (wall), the flow path plate, and the nozzle plate are joined in this order by bonding or the like on the opposite side of the diaphragm from the piezoelectric body.

  When joining these thin plate-shaped members, it is necessary to ensure the positioning accuracy and the accuracy of the application amount (thickness) of the adhesive between the members to be joined. However, since the thin plate-like members forming this laminated body are thin and some are finely processed, it is difficult to laminate them with high positioning accuracy. In addition, since the amount of adhesive necessary for joining the thin plate members is very small, it is very difficult to control the thickness of the adhesive. Therefore, in order to form a laminated body from these thin plate-like members, various contrivances have been made to the laminating method and joining method, such as forming a plurality of members integrally in order to omit the joining step.

  In the ceramic ink jet head described in Patent Document 1 and the manufacturing method thereof, as a means for avoiding the problems of the adhesive chamber positioning and adhesive thickness variations, a photosensitive resin is used as a means to avoid pressure chamber, flow path, and empty space. It is configured to create a hole matrix.

  Further, in the ink jet recording head described in Patent Document 2 and the manufacturing method thereof, a metal thin plate is applied on a hole pattern made of a photosensitive resin, and a piezoelectric material and an electrode material are alternately laminated to make the photosensitive resin. The pore pattern is dissolved in the baking process to form an ink cavity having a metal foil film applied to the inner surface.

  In addition, in the ink jet recording head described in Patent Document 3 and the manufacturing method thereof, a cylindrical pressure chamber forming portion and a small-diameter flow path forming portion formed at both ends are combined with a solution of an electrode material and a piezoelectric material. It is configured to alternately immerse in the solution a plurality of times, remove the hole pattern member in the debinding step, and alternately form a plurality of electrode layers and piezoelectric layers.

  In addition, the ink jet recording head described in Patent Document 4 is configured such that piezoelectric bodies are stacked in the nozzle pitch direction and a hole portion serving as a pressure chamber is provided by a sheet.

In addition, in the inkjet head and the manufacturing method thereof described in Patent Document 5, the inkjet head is formed by stacking green sheets, and the ink flow path pattern is formed on the green sheet using a photosensitive resin in the inkjet head. In addition, the ink flow path pattern is formed by firing after removing the binder from the laminate in which these green sheets are laminated.
Japanese Patent Publication No. 7-96301 JP-A-8-25625 JP-A-8-20109 JP 2001-334661 A Japanese Unexamined Patent Publication No. 2-33311

However, the thickness of the piezoelectric element must be reduced when driving the d ₃₁ mode piezoelectric element at a low voltage, or when there are restrictions on the dimensions and mounting position of the piezoelectric element for high density. There is. There are restrictions in handling to make a very thin piezoelectric element (for example, 20 to 30 μm thick) using green sheets or bulk. Once the layers are stacked to obtain a handleable thickness, A method of processing to a predetermined thickness by polishing or sand blasting after the pressure forming and firing is used, and post-processing such as polishing or sand blasting is essential. Therefore, the processing cost is increased due to post-processing, and there arises a problem that it is difficult to control the thickness by polishing or sandblasting.

  In addition, when a thin plate such as a green sheet is made of a single layer, the piezoelectric element may be warped due to the heat generated when the piezoelectric element is fired, and bonding failure with the vibration plate may occur, or the entire print head may be warped. I sometimes get up. In particular, in a piezoelectric element for a long head such as a full-line head corresponding to the entire width of the printable area of the printing medium, warpage appears remarkably in the longitudinal direction. When the print head is warped, the ink landing position on the print medium is displaced, and the printing performance is deteriorated.

  In the ceramic ink jet head and the manufacturing method thereof described in Patent Document 1, a method of integrally forming a pressure chamber and a laminated piezoelectric body in order to remove the bonding process is disclosed. The warpage is not disclosed.

  In addition, the inkjet recording head and the manufacturing method thereof described in Patent Document 2 are aimed at preventing dimensional change of the ink cavity and the loss of the piezoelectric body in the firing process of the piezoelectric body. Is not disclosed.

  In addition, the inkjet recording head and the method for manufacturing the same described in Patent Document 3 are intended to improve dimensional accuracy, be easy to manufacture, and reduce the price, and do not disclose the thinning of the piezoelectric body and the prevention of warping.

  Further, in the ink jet recording head described in Patent Document 4, when the width of the piezoelectric element is widened, the nozzle density is lowered, so that it is difficult to increase the density (multiple). Moreover, the wiring drawing method becomes complicated, and it is difficult to obtain the placement accuracy.

  Further, in the ink jet head and the manufacturing method thereof described in Patent Document 5, it is necessary to reduce the thickness of each layer in order to increase the density, and the strength of the entire print head may be reduced.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a discharge head and a discharge head manufacturing method capable of easily manufacturing a thin plate-shaped piezoelectric body and preventing warpage occurring when the piezoelectric body is fired. To do.

  In order to achieve the above object, the invention according to claim 1 is an ejection head for ejecting liquid droplets on a medium to be ejected, in which electrode materials and piezoelectric materials are alternately laminated, and distortion occurs when an electric field is applied. A piezoelectric substrate including a piezoelectric active part, a pressure chamber that is laminated and bonded to the piezoelectric substrate, and stores a liquid to be discharged onto the discharge target medium, and a liquid flow path when the liquid is supplied to the pressure chamber And the piezoelectric substrate has a deformable low-rigidity portion in which a piezoelectric material is missing inside the piezoelectric substrate on the side opposite to the surface on which the pressure chamber of the piezoelectric active portion is laminated and bonded. It is characterized by having.

  That is, the piezoelectric substrate that has a deformed low-rigidity portion in which the piezoelectric material is missing is located inside the piezoelectric substrate opposite to the pressure chamber of the piezoelectric active portion. The thickness of the active part can be reduced. Therefore, the piezoelectric substrate is easy to handle at the time of manufacture, and the processing of the piezoelectric active portion by polishing or sandblasting to obtain a piezoelectric active portion having a small thickness is not required. Can be prevented, and reliability is expected to improve.

  The piezoelectric active portion includes a portion where distortion occurs when an electric field (driving voltage) is applied to the piezoelectric body, and includes an individual electrode arrangement region to which the driving voltage is applied. In other words, the piezoelectric active portion has a structure in which electrodes are provided on both surfaces thereof, and functions as a piezoelectric actuator that applies discharge force to the liquid in the pressure chamber in accordance with a drive signal applied to one electrode (individual electrode). .

  The piezoelectric body includes a single-layer piezoelectric body composed of a single layer and a multilayer (stacked) piezoelectric body in which a plurality of piezoelectric layers are stacked. In a laminated piezoelectric material, an electrode layer is formed between piezoelectric layers, each piezoelectric layer has a structure sandwiched between electrode layers, one electrode is a common electrode connected to a reference potential of a drive signal, and the other These electrodes become individual electrodes to which a drive signal (drive voltage) is applied.

  In addition, the piezoelectric body includes an electrode-divided piezoelectric body that includes a plurality of individual electrodes in one piezoelectric body and controls each individual electrode independently to allow one piezoelectric body to function equivalently as a plurality of piezoelectric bodies. May be included.

  A piezoelectric ceramic such as lead zirconate titanate or barium titanate may be applied to the piezoelectric material.

  The flow path forming member may be bonded with a discharge hole member in which a droplet discharge hole is provided corresponding to the pressure chamber on the side surface opposite to the surface to which the piezoelectric substrate is bonded. May be formed integrally with the flow path member.

  In an aspect in which the piezoelectric substrate and the flow path member are laminated and bonded, the flow path member may be directly bonded to one surface of the piezoelectric substrate, or the piezoelectric substrate and the flow path member may be connected via another member. You may join.

  The deformation-use low-rigidity portion provided inside the piezoelectric substrate may be a cavity (void) or may be filled with a member having rigidity lower than that of the piezoelectric material. Further, the low rigidity portion for deformation may be sealed with a piezoelectric substrate, or may be communicated with the outside of the piezoelectric substrate through an opening or a hole.

  The ejection head includes a full line type ejection head in which ejection holes for ejecting droplets are arranged over a length corresponding to the entire width of the ejection medium, and a liquid over a length shorter than the length corresponding to the entire width of the ejection medium. There is a serial type discharge head (shuttle scan type discharge head) that discharges droplets onto a discharge medium while scanning a short head in which discharge holes for discharging droplets are arranged in the width direction of the discharge medium.

  In addition, in a full-line type ejection head, short heads having short ejection hole arrays that are less than the length corresponding to the full width of the medium to be ejected are arranged in a staggered manner and connected to form the full width of the medium to be ejected. It may be a corresponding length.

  As shown in claim 2, the invention described in claim 1 is characterized in that the piezoelectric active portion includes a bimorph type piezoelectric body formed by laminating two layers of piezoelectric bodies.

  A bimorph piezoelectric body is formed by laminating two piezoelectric bodies (bonded in the thickness direction) and using the piezoelectric lateral effect, each layer is distorted in the opposite direction to each other (one extending in the lateral direction and the other in the lateral direction). It includes a piezoelectric body that obtains a bending displacement by shrinking.

  Moreover, as shown in claim 3, the invention described in claim 1 includes a diaphragm that deforms according to the distortion of the piezoelectric active portion between the piezoelectric substrate and the flow path member. It is characterized by.

  The diaphragm may be formed using a piezoelectric material or a non-piezoelectric material.

  According to a fourth aspect of the present invention, the diaphragm according to the third aspect is characterized in that the diaphragm is formed of a material including a piezoelectric member and is integrally formed with the piezoelectric substrate.

  That is, by integrally forming the diaphragm with the piezoelectric substrate, the step of bonding the diaphragm to the piezoelectric substrate can be omitted, so that poor bonding can be prevented and reliability can be improved.

  A mode in which a liquid-resistant treatment is applied to a portion where the diaphragm is in contact with the liquid is preferable.

  In addition, as shown in claim 5, the invention described in any one of claims 1 to 4 is characterized in that the flow path member is formed of a material including a non-piezoelectric member.

  That is, by forming the flow path member with a non-piezoelectric material, the liquid suitability (liquid resistance) of the pressure chamber included in the flow path member and the liquid flow path communicating with the pressure chamber is improved.

Further, according to a sixth aspect of the present invention, the invention described in any one of the first to fifth aspects is characterized in that the piezoelectric active portion includes a piezoelectric body that generates a d ₃₁ mode displacement. .

When a piezoelectric body that generates a d ₃₁ mode displacement is applied to the piezoelectric active portion, it is inexpensive and wiring is easy.

When a diaphragm is joined to a piezoelectric body that generates a d ₃₁ mode displacement, the diaphragm can be displaced in the vertical direction in accordance with a lateral strain (piezoelectric lateral effect) of the piezoelectric body. In addition, an individual electrode is provided in a portion where the distortion of the piezoelectric body is generated.

Also, by laminating two piezoelectric materials that generate a d ₃₁ mode displacement, and using the piezoelectric lateral effect, each layer is distorted in opposite directions (one stretches laterally and the other shrinks laterally). A bimorph piezoelectric body that obtains bending displacement can be formed.

  According to a seventh aspect of the present invention, in the invention described in any one of the first to sixth aspects, the piezoelectric substrate includes the low rigidity portion for deformation and the piezoelectric body inside the piezoelectric substrate. A low-rigidity portion for preventing warpage in which a piezoelectric material is missing is provided at a position symmetrical to the thickness direction of the substrate.

  That is, since the low-rigidity portion for warpage prevention is provided at a position symmetrical to the laminating direction (thickness direction) of the low-rigidity portion for deformation and the piezoelectric substrate, warpage that occurs when heat is applied to the piezoelectric substrate for firing. Can be suppressed.

  It is preferable that the low rigidity portion for deformation and the low rigidity portion for warpage prevention have the same shape and the same size.

  Further, as shown in claim 8, in the invention described in any one of claims 1 to 7, the piezoelectric substrate is not distorted even if an electric field inside the piezoelectric substrate is applied. The piezoelectric inactive portion is provided with a low-rigidity portion for preventing interference in which a piezoelectric material is missing.

  That is, if a low-rigidity portion for preventing interference is provided in a piezoelectric inactive portion that does not cause distortion even when an electric field is applied, adjacent crosstalk that occurs when driving a piezoelectric body in an adjacent pressure chamber can be mitigated. .

  According to a ninth aspect of the present invention, in the eighth aspect of the invention, the piezoelectric substrate is symmetrical in the thickness direction of the piezoelectric substrate of the low rigidity portion for preventing interference inside the piezoelectric substrate. It is characterized by having a low-rigidity part for preventing interference by warping at a position.

  In other words, by providing a low-rigidity portion for preventing warpage and a low-rigidity portion for preventing warpage at positions symmetrical to the thickness direction of the piezoelectric substrate, even if it has a low-rigidity portion for preventing interference, it occurs when the piezoelectric substrate is fired. Warping can be suppressed.

  In order to achieve the above object, the invention described in claim 10 is a method of manufacturing an ejection head for ejecting liquid droplets on a medium to be ejected, wherein electrode materials and piezoelectric materials are alternately laminated, and an electric field is produced. A piezoelectric substrate forming step for forming a piezoelectric substrate including a piezoelectric active part that generates distortion when the pressure is applied, a pressure chamber for storing liquid to be discharged onto the discharge target medium on the piezoelectric substrate, and the pressure chamber A bonding step of laminating and bonding a flow path member in which a liquid flow path is formed when the liquid is supplied, wherein the piezoelectric substrate forming step includes the piezoelectric member on the side opposite to the pressure chamber of the piezoelectric active portion. It includes a deforming low-rigidity portion forming step of forming a deforming low-rigidity portion in which a piezoelectric material is missing inside the body substrate.

  The hollow portion formed as the low rigidity portion for deformation may include a filling step of filling the low rigidity portion for deformation with a member having lower rigidity than the piezoelectric substrate.

  According to an eleventh aspect of the present invention, in the tenth aspect of the invention, the deformation low-rigidity portion forming step removes at least a part of the piezoelectric substrate including a member having a rigidity lower than that of the piezoelectric material. A piezoelectric material is laminated on the deformation low rigidity portion removal layer forming step and the deformation low rigidity portion removal layer formed by the deformation low rigidity portion removal layer. Piezoelectric layer laminating step, and at the time of firing the piezoelectric substrate by applying heat to the piezoelectric substrate after the piezoelectric layer laminating step, at least a part of the low-rigidity portion removing layer for deformation is removed and the piezoelectric material And a heating step in which the deforming low-rigidity portion lacking is formed.

  A member that is removed at least partly burned out (dissolved) by the heat in the heating process is applied to the low rigidity portion removing layer for deformation. A binder resin or the like may be applied to the member.

  By the heating process, the deformation-use low rigidity portion removal layer may be completely removed, or a part of the deformation-use low rigidity portion removal layer may remain.

  According to a twelfth aspect of the invention, in the eleventh aspect of the invention, the piezoelectric substrate is laminated with each of the deformation low-rigidity portion removing layer and the piezoelectric substrate in the piezoelectric substrate. Including a step for forming a low-rigidity removing layer for preventing warpage, wherein a low-rigidity removing layer for preventing warpage is formed in which at least a part including a member having rigidity lower than that of the piezoelectric material is removed at a position symmetrical to the thickness direction. The heating step removes at least a part of the low-rigidity removing layer for preventing warpage to form a low-rigidity portion for preventing warping in which a piezoelectric material is missing.

  It is preferable that the low-rigidity removing layer forming step for preventing warpage uses the same technique as the deforming low-rigidity removing layer forming step.

  According to a thirteenth aspect, in the tenth, eleventh or twelfth aspect of the invention, a non-piezoelectric material is provided between the piezoelectric substrate and the flow path member on the piezoelectric substrate after the heating step. The present invention is characterized by including a diaphragm joining step of joining diaphragms formed of a material containing.

  Methods such as adhesion using an adhesive can be applied to the bonding of the diaphragm and the piezoelectric substrate and the bonding of the flow path member and the diaphragm.

  According to a fourteenth aspect of the present invention, the invention described in any one of the tenth to thirteenth aspects causes the electric field inside the piezoelectric substrate to act by post-processing after the ejection force applying member forming step. However, the present invention is characterized by including an interference preventing low-rigidity portion forming step of forming an interference-preventing low-rigidity portion in which a piezoelectric material is missing in a piezoelectric inactive portion that does not cause distortion.

  That is, after firing the piezoelectric substrate, the low rigidity portion for interference prevention is formed by post-processing, so the low rigidity portion for preventing warpage interference formed in pairs with the low rigidity portion for interference prevention is formed to prevent warpage. There is no need to let them.

  The shape of the interference preventing low-rigidity portion may be a groove shape or a hole shape. Also, a plurality of interference-preventing low-rigidity parts may be provided in one piezoelectric inactive part.

  According to the present invention, since the piezoelectric substrate on the side opposite to the pressure chamber of the piezoelectric active portion has the low rigidity portion for deformation lacking the piezoelectric material, the piezoelectric active portion can be obtained even if the thickness of the piezoelectric substrate is increased. Can be made thinner. Therefore, the piezoelectric substrate is easy to handle at the time of manufacture, and when the piezoelectric active portion having a small thickness is obtained, the processing of the piezoelectric active portion by polishing, sandblasting, or the like is not required. Can be prevented, and reliability is expected to improve.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[Overall Configuration of Inkjet Recording Apparatus Mounted with Print Head According to the Present Invention]
FIG. 1 is an overall configuration diagram of an ink jet recording apparatus equipped with a print head according to an embodiment of the present invention. As shown in the figure, the inkjet recording apparatus 10 includes a print unit 12 having a plurality of print heads 12K, 12C, 12M, and 12Y provided for each ink color, and each print head 12K, 12C, 12M, An ink storage / loading unit 14 for storing ink to be supplied to 12Y, a paper feeding unit 18 for supplying recording paper 16, a decurling unit 20 for removing curling of the recording paper 16, and a nozzle of the printing unit 12 A suction belt transport unit 22 that is disposed to face a surface (ink ejection surface) and transports the recording paper 16 while maintaining the flatness of the recording paper 16, and a print detection unit 24 that reads a printing result by the printing unit 12, A paper discharge unit 26 that discharges the printed recording paper 16 (printed material) to the outside.

  In FIG. 1, a magazine for rolled paper (continuous paper) is shown as an example of the paper supply unit 18, but a plurality of magazines having different paper widths, paper quality, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  When multiple types of recording paper are used, an information recording body such as a barcode or wireless tag that records paper type information is attached to the magazine, and the information on the information recording body is read by a predetermined reader. Therefore, it is preferable to automatically determine the type of paper to be used and perform ink ejection control so as to realize appropriate ink ejection according to the type of paper.

  The recording paper 16 delivered from the paper supply unit 18 retains curl due to having been loaded in the magazine. In order to remove this curl, heat is applied to the recording paper 16 by the heating drum 30 in the direction opposite to the curl direction of the magazine in the decurling unit 20. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  In the case of an apparatus configuration that uses roll paper, a cutter (first cutter) 28 is provided as shown in FIG. 1, and the roll paper is cut into a desired size by the cutter 28. The cutter 28 includes a fixed blade 28A having a length equal to or greater than the conveyance path width of the recording paper 16, and a round blade 28B that moves along the fixed blade 28A. The fixed blade 28A is provided on the back side of the print. The round blade 28B is disposed on the printing surface side with the conveyance path interposed therebetween. Note that the cutter 28 is not necessary when cut paper is used.

  After the decurling process, the cut recording paper 16 is sent to the suction belt conveyance unit 22. The suction belt conveyance unit 22 has a structure in which an endless belt 33 is wound between rollers 31 and 32, and at least portions facing the nozzle surface of the printing unit 12 and the sensor surface of the printing detection unit 24 are horizontal ( Flat surface).

  The belt 33 has a width that is greater than the width of the recording paper 16, and a plurality of suction holes (not shown) are formed on the belt surface. As shown in FIG. 1, a suction chamber 34 is provided at a position facing the nozzle surface of the print unit 12 and the sensor surface of the print detection unit 24 inside the belt 33 spanned between the rollers 31 and 32. Then, the suction chamber 34 is sucked by the fan 35 to be a negative pressure, whereby the recording paper 16 on the belt 33 is sucked and held.

  When the power of a motor (not shown in FIG. 1, described as reference numeral 88 in FIG. 7) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, the belt 33 rotates in the clockwise direction in FIG. , And the recording paper 16 held on the belt 33 is conveyed from left to right in FIG.

  Since ink adheres to the belt 33 when a borderless print or the like is printed, the belt cleaning unit 36 is provided at a predetermined position outside the belt 33 (an appropriate position other than the print area). Although details of the configuration of the belt cleaning unit 36 are not shown, for example, there are a method of niping a brush roll, a water absorbing roll, etc., an air blow method of blowing clean air, or a combination thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

  Although an embodiment using a roller / nip conveyance mechanism instead of the suction belt conveyance unit 22 is also conceivable, if the roller / nip conveyance is performed in the printing area, the roller contacts the printing surface of the recording paper 16 immediately after printing, so that the image is displayed. There is a problem of easy bleeding. Therefore, as in this example, suction belt conveyance that does not bring the image surface into contact with each other in the print region is preferable.

  A heating fan 40 is provided on the upstream side of the printing unit 12 on the recording paper conveyance path formed by the suction belt conveyance unit 22. The heating fan 40 heats the recording paper 16 by blowing heated air onto the recording paper 16 before printing. Heating the recording paper 16 immediately before printing makes it easier for the ink to dry after landing.

  The printing unit 12 is a so-called full line type head in which line type heads having a length corresponding to the maximum paper width are arranged in a direction (main scanning direction) orthogonal to the recording paper conveyance direction (see FIG. 2). Although a detailed structural example will be described later (FIGS. 3 to 5), each of the print heads 12K, 12C, 12M, and 12Y is a recording paper of the maximum size targeted by the inkjet recording apparatus 10 as shown in FIG. The line head includes a plurality of ink discharge ports (nozzles) arranged over a length exceeding at least one side of 16.

  A print head corresponding to each color ink in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side along the feeding direction of the recording paper 16 (hereinafter referred to as the recording paper transport direction). 12K, 12C, 12M, and 12Y are arranged. A color image can be formed on the recording paper 16 by discharging the color inks from the print heads 12K, 12C, 12M, and 12Y while the recording paper 16 is conveyed.

  Thus, according to the printing unit 12 in which the full line head that covers the entire area of the paper width is provided for each ink color, the operation of relatively moving the recording paper 16 and the printing unit 12 in the sub-scanning direction is performed once. An image can be recorded on the entire surface of the recording paper 16 only by performing it (that is, by one sub-scan). Thereby, it is possible to perform high-speed printing as compared with a shuttle type head in which the print head reciprocates in the main scanning direction, and productivity can be improved.

  In this example, the configuration of KCMY standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink and dark ink are added as necessary. May be. For example, it is possible to add a print head that discharges light ink such as light cyan and light magenta.

  As shown in FIG. 1, the ink storage / loading unit 14 has tanks that store inks of colors corresponding to the print heads 12K, 12C, 12M, and 12Y, and each tank is connected via a conduit (not shown). The print heads 12K, 12C, 12M, and 12Y communicate with each other. Further, the ink storage / loading unit 14 includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. ing.

  The print detection unit 24 includes an image sensor for imaging the droplet ejection result of the print unit 12, and functions as a means for checking nozzle clogging and other ejection defects from the droplet ejection image read by the image sensor.

  The print detection unit 24 of this example is composed of a line sensor having a light receiving element array that is wider than at least the ink ejection width (image recording width) by the print heads 12K, 12C, 12M, and 12Y. The line sensor includes an R sensor row in which photoelectric conversion elements (pixels) provided with red (R) color filters are arranged in a line, a G sensor row provided with green (G) color filters, The color separation line CCD sensor is composed of a B sensor array provided with a blue (B) color filter. Instead of the line sensor, an area sensor in which the light receiving elements are two-dimensionally arranged can be used.

  The print detection unit 24 reads the test pattern printed by the print heads 12K, 12C, 12M, and 12Y for each color, and detects the ejection of each print head. The ejection determination includes the presence / absence of ejection, measurement of dot size, measurement of dot landing position, and the like.

  A post-drying unit 42 is provided following the print detection unit 24. The post-drying unit 42 is means for drying the printed image surface, and for example, a heating fan is used. Since it is preferable to avoid contact with the printing surface until the ink after printing is dried, a method of blowing hot air is preferred.

  When printing on porous paper with dye-based ink, the weather resistance of the image is improved by preventing contact with ozone or other substances that cause dye molecules to break by pressurizing the paper holes with pressure. There is an effect to.

  A heating / pressurizing unit 44 is provided following the post-drying unit 42. The heating / pressurizing unit 44 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 45 having a predetermined surface uneven shape while heating the image surface to transfer the uneven shape to the image surface. To do.

  The printed matter generated in this manner is outputted from the paper output unit 26. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. The ink jet recording apparatus 10 is provided with a sorting means (not shown) that switches the paper discharge path so as to select the print product of the main image and the print product of the test print and send them to the discharge units 26A and 26B. Yes. Note that when the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by a cutter (second cutter) 48. The cutter 48 is provided immediately before the paper discharge unit 26, and cuts the main image and the test print unit when the test print is performed on the image margin. The structure of the cutter 48 is the same as that of the first cutter 28 described above, and includes a fixed blade 48A and a round blade 48B.

  Although not shown in FIG. 1, the paper output unit 26A for the target prints is provided with a sorter for collecting prints according to print orders.

  Next, the structure of the print head will be described. Since the structures of the print heads 12K, 12C, 12M, and 12Y provided for the respective ink colors are common, the print heads are represented by reference numeral 50 in the following.

  FIG. 3 (a) is a plan perspective view showing an example of the structure of the print head 50, and FIG. 3 (b) is an enlarged view of a part thereof. 3C is a perspective plan view showing another example of the structure of the print head 50, and FIG. 4 is a sectional view showing the three-dimensional configuration of the ink chamber unit (along line 4-4 in FIG. 3B). FIG. In FIG. 4, the ink ejection direction is shown upward.

  In order to increase the dot pitch printed on the recording paper surface, it is necessary to increase the nozzle pitch in the print head 50. As shown in FIGS. 3A to 3C and FIG. 4, the print head 50 of this example includes a plurality of nozzles 51 from which ink droplets are ejected and pressure chambers 52 corresponding to the nozzles 51. It has a structure in which the ink chamber units 53 are arranged in a staggered matrix, thereby achieving a high density of the apparent nozzle pitch.

  That is, as shown in FIGS. 3A and 3B, the print head 50 according to the present embodiment has a plurality of nozzles 51 for ejecting ink in the full width of the recording paper 16 in a direction substantially perpendicular to the recording paper transport direction. A full line head having one or more nozzle rows arranged over corresponding lengths.

  Further, as shown in FIG. 3 (c), short two-dimensionally arranged heads 50 'may be arranged in a staggered manner and connected to form a length corresponding to the entire width of the print medium.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and nozzles 51 and supply ports 54 (not shown in FIG. 4) are provided at both corners on the diagonal line. It has been. Each pressure chamber 52 communicates with a common channel (not shown) via a supply port 54.

  As shown in FIG. 4, the ink chamber unit 53 (print head 50) includes a piezoelectric substrate 55 on which a multilayer piezoelectric body is formed by alternately laminating an electrode material forming an electrode layer and a piezoelectric material serving as a piezoelectric body. A common electrode 55A is provided on the uppermost surface. The piezoelectric substrate 55 may be formed so that the uppermost layer of the piezoelectric substrate 55 becomes an electrode layer, and the electrode layer serving as the uppermost layer may be used as the common electrode 55A.

  A metal material such as gold, silver, copper, nickel, or platinum is applied to the electrode material that forms the electrode layer, and lead zirconate titanate or barium titanate is used as the piezoelectric material that forms the piezoelectric layer.

  A diaphragm 56 is provided on the surface of the common electrode 55A opposite to the piezoelectric substrate 55. The diaphragm 56 is made of a metal material and is electrically connected to the common electrode 55A. In addition, you may comprise so that the diaphragm 56 and the common electrode 55A may be combined. In addition to the metal material, various materials such as a metal oxide, silicon, a resin, and a piezoelectric material can be applied to the material of the diaphragm 56. When a piezoelectric material is applied to the diaphragm 56, the piezoelectric substrate 55 and the diaphragm 56 are integrally formed so that an inactive portion of the piezoelectric body (a region where no distortion occurs even when a drive signal is given) is diaphragm. 56 may be used.

  Further, a pressure chamber 52, a supply port 54 (not shown in FIG. 4), and a flow path member 52A in which the common flow path is formed are provided on the surface of the diaphragm 56 opposite to the common electrode 55A. A nozzle plate 51A on which the nozzles 51 are formed is provided on the surface of the path member 52A opposite to the diaphragm 56.

  Of the flow path member 52A (pressure chamber plate in which the pressure chamber 52 is formed), an opening is formed in a region to be the pressure chamber 52. When the flow path member 52A and the vibration plate 56 are joined, the vibration plate 56 forms one wall surface of the pressure chamber 52. Therefore, the vibration plate 56 is ink resistant at least in a portion that becomes the wall surface of the pressure chamber 52. A material with is used. In addition, an ink-resistant treatment may be performed on at least a portion (a portion in contact with ink) that becomes the wall surface of the pressure chamber 52 of the diaphragm 56.

  The flow path member 52A is made of a non-piezoelectric material having a predetermined rigidity such as metal or resin. The flow path member 52A may be configured by laminating a pressure chamber 52, a cavity plate in which the common flow path, an opening, a hole, a groove, and the like to be the supply port shown in FIG. 4 are formed.

  That is, among the wall surfaces forming the pressure chamber 52, five wall surfaces other than the wall surface to which the diaphragm 56 is joined are formed using a non-piezoelectric material. When a non-piezoelectric material is used for the diaphragm 56, a non-piezoelectric material is used for the wall surface forming the pressure chamber 52.

  Note that an adhesive may be used to bond the diaphragm 56 and the flow path member 52A, and the flow path member 52A and the nozzle plate 51A may be bonded, or other bonding methods may be used.

  On the other hand, the individual electrode 57 is attached to the piezoelectric layer of the piezoelectric substrate 55 that is closest to the pressure chamber. That is, an individual electrode 57 to which a drive signal is applied when ink is ejected is joined to a position corresponding to the pressure chamber 52 inside the piezoelectric substrate 55 (lower portion of the pressure chamber 52 in FIG. 4).

  In other words, the individual electrode 57 is joined to the surface of the piezoelectric layer (one layer) closest to the pressure chamber on the opposite side of the diaphragm 56 and the common electrode 55A. The individual electrode 57 is made of a metal material such as gold, silver, copper, nickel, or platinum, or a metal oxide material, like the common electrode 55A.

  A region to which the individual electrode 57 on the most pressure chamber side of the piezoelectric layer is bonded has a function as a piezoelectric active portion 58 in which distortion occurs according to the drive signal. That is, the piezoelectric body sandwiched between the common electrode 55A and the individual electrode 57 functions as a piezoelectric active part 58 that generates a piezoelectric effect.

When a drive signal is applied to the individual electrode 57, the piezoelectric active portion 58 is distorted in a direction (right and left direction in FIG. 4) substantially orthogonal to the direction of the electric field due to the electric field generated between the common electrode 55A and the individual electrode 57. As a result, the piezoelectric active portion 58 functions as a d ₃₁ mode (piezoelectric lateral effect) piezoelectric body.

  The diaphragm 56 is deformed in the vertical direction in FIG. 4 according to the distortion of the piezoelectric active portion 58 described above, and the volume of the pressure chamber 52 is changed according to the displacement of the diaphragm 56. An ink amount corresponding to the change amount is ejected from the nozzle 51.

  That is, when the piezoelectric active portion 58 including the single-layer piezoelectric body is driven by unimorph, the vibration plate 56 is displaced in the ink discharge direction (the direction from the bottom to the top in FIG. 4) and the opposite direction to the pressure chamber 52. The stored ink can be ejected from the nozzle 51.

  Further, a deforming low-rigidity portion 59 is provided on the surface of the piezoelectric active portion 58 opposite to the individual electrode 57. As shown in FIG. 4, the deformation-use low-rigidity portion 59 may be provided with a hollow portion, or a low-rigidity member having rigidity lower than that of the piezoelectric body may be used.

The low rigidity portion 59 for deformation includes a glass-based material, a glass fiber material, a titanium (Ti) alloy, a low Young's modulus metal, a nanocomposite material (Si ₃ N ₄ / BN, AIN / BN, Al ₂ O ₃ / BN, SIC / BN) or the like may be used. Further, the low rigidity portion 59 for deformation may be communicated with the outside of the piezoelectric substrate 55 or may not be communicated with the outside of the piezoelectric substrate 55.

  As described above, by providing the low rigidity portion having rigidity lower than that of the piezoelectric substrate 55 on the surface opposite to the piezoelectric active portion 58 of the individual electrode 57, the diaphragm 56 is displaced when the drive signal is applied. Thus, the piezoelectric active portion 58 (piezoelectric actuator) that is sufficiently thinner than the thickness of the piezoelectric substrate 55 can be formed.

  As shown in FIG. 5, a large number of ink chamber units 53 having such a structure are arranged along a row direction along the main scanning direction and an oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. The structure is arranged in a grid pattern. With a structure in which a plurality of ink chamber units 53 are arranged at a constant pitch d along a certain angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is d × cos θ. .

  That is, in the main scanning direction, each nozzle 51 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction. Hereinafter, for convenience of explanation, it is assumed that the nozzles 51 are linearly arranged at a constant interval (pitch P) along the longitudinal direction (main scanning direction) of the head.

  When the nozzles are driven by a full line head having a nozzle row corresponding to the full width of the paper, (1) all the nozzles are driven simultaneously, (2) the nozzles are sequentially driven from one side to the other (3) ) The nozzles are divided into blocks, and drive control such as sequentially driving from one side to the other for each block is performed, and one row of dots in the width direction of the recording paper 16 (direction perpendicular to the recording paper transport direction) Nozzle driving that prints a line or a line composed of a plurality of rows of dots is defined as main scanning.

  In particular, when the nozzles 51 arranged in the matrix as shown in FIG. 5 are driven, the main scanning as described in the above (3) is preferable. That is, the nozzles 51-11, 51-12, 51-13, 51-14, 51-15, 51-16 are made into one block (other nozzles 51-21,..., 51-26 are made into one block, The nozzles 51-31,..., 51-36 are set as one block,..., And the recording paper 16 is driven by sequentially driving the nozzles 51-11, 51-12,. One line is printed in the width direction.

  On the other hand, the sub-scan is defined as the above-described full-line head and the paper are moved relative to each other to repeatedly print a line composed of one row of dots or a line composed of a plurality of rows of dots formed by the above-described main scan. To do.

  In the implementation of the present invention, the nozzle arrangement structure is not limited to the illustrated example. For example, one nozzle row may be arranged in the main scanning direction, or an arrangement having a plurality of nozzles in the sub-scanning direction may be used.

  FIG. 6 is a schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus 10.

  The ink supply tank 60 is a base tank for supplying ink, and is installed in the ink storage / loading unit 14 described with reference to FIG. There are two types of ink supply tank 60: a system that replenishes ink from a replenishment port (not shown) and a cartridge system that replaces the entire tank when the ink remaining amount is low. A cartridge system is suitable for changing the ink type according to the intended use. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type. The ink supply tank 60 in FIG. 6 is equivalent to the ink storage / loading unit 14 in FIG. 1 described above.

  As shown in FIG. 6, a filter 62 is provided between the ink supply tank 60 and the print head 50 in order to remove foreign substances and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter (generally about 20 μm).

  Although not shown in FIG. 6, a configuration in which a sub tank is provided in the vicinity of the print head 50 or integrally with the print head 50 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head.

  Further, the inkjet recording apparatus 10 is provided with a cap 64 as a means for preventing the nozzle 51 from drying or preventing an increase in ink viscosity near the nozzle, and a cleaning blade 66 as a nozzle surface cleaning means.

  The maintenance unit including the cap 64 and the cleaning blade 66 can be moved relative to the print head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the print head 50 as necessary. The

  The cap 64 is displaced up and down relatively with respect to the print head 50 by an elevator mechanism (not shown). The cap 64 is raised to a predetermined raised position when the power is turned off or during printing standby, and is brought into close contact with the print head 50, thereby covering the nozzle surface with the cap 64.

  During printing or standby, if the frequency of use of a specific nozzle 51 is reduced and ink is not ejected for a certain period of time, the ink solvent near the nozzle evaporates and the ink viscosity increases. In such a state, ink cannot be ejected from the nozzle 51 even if the piezoelectric active portion 58 operates.

  Before this state is reached (within the range of viscosity that can be discharged by the operation of the piezoelectric active portion 58), the piezoelectric active portion 58 is operated, and the deteriorated ink (ink near the nozzle whose viscosity has increased) is discharged. Accordingly, preliminary discharge (purge, idle discharge, collar discharge, dummy discharge) is performed toward the cap 64 (ink receiver).

  Further, when air bubbles are mixed into the ink in the print head 50 (in the pressure chamber 52), the ink cannot be ejected from the nozzle even if the piezoelectric active portion 58 is operated. In such a case, the cap 64 is applied to the print head 50, the ink in the pressure chamber 52 (ink mixed with bubbles) is removed by suction with the suction pump 67, and the suctioned and removed ink is sent to the collection tank 68. .

  In this suction operation, the deteriorated ink with increased viscosity (solidified) is sucked out when the ink is initially loaded into the head or when the ink is used after being stopped for a long time. Since the suction operation is performed on the entire ink in the pressure chamber 52, the amount of ink consumption increases. Therefore, it is preferable to perform preliminary ejection when the increase in ink viscosity is small.

  The cleaning blade 66 is made of an elastic member such as rubber, and can slide on the ink discharge surface (surface of the nozzle plate) of the print head 50 by a blade moving mechanism (wiper) (not shown). When ink droplets or foreign substances adhere to the nozzle plate, the nozzle plate surface is wiped by sliding the cleaning blade 66 on the nozzle plate to clean the nozzle plate surface. It should be noted that when the ink ejection surface is cleaned by the blade mechanism, preliminary ejection is performed in order to prevent foreign matter from being mixed into the nozzle 51 by the blade.

  FIG. 7 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The inkjet recording apparatus 10 includes a communication interface 70, a system controller 72, a memory 74, a motor driver 76, a heater driver 78, a print control unit 80, an image buffer memory 82, a head driver 84, and the like.

  The communication interface 70 is an interface unit that receives image data sent from the host computer 86. As the communication interface 70, a serial interface such as USB, IEEE 1394, Ethernet, and wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. The image data sent from the host computer 86 is taken into the inkjet recording apparatus 10 via the communication interface 70 and temporarily stored in the memory 74. The memory 74 is a storage unit that temporarily stores an image input via the communication interface 70, and data is read and written through the system controller 72. The memory 74 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 72 is a control unit that controls the communication interface 70, the memory 74, the motor driver 76, the heater driver 78, and the like. The system controller 72 includes a central processing unit (CPU) and its peripheral circuits, and performs communication control with the host computer 86, read / write control of the memory 74, and the like, and controls the motor 88 and heater 89 of the transport system. A control signal to be controlled is generated.

  The motor driver 76 is a driver (drive circuit) that drives the motor 88 in accordance with an instruction from the system controller 72. The heater driver 78 is a driver that drives the heater 89 such as the post-drying unit 42 in accordance with an instruction from the system controller 72.

  The print control unit 80 has a signal processing function for performing various processing and correction processing for generating a print control signal from image data in the memory 74 in accordance with the control of the system controller 72, and the generated print control. A control unit that supplies a signal (print data) to the head driver 84. Necessary signal processing is performed in the print controller 80, and the ejection amount and ejection timing (droplet ejection control) of the ink droplets of the print head 50 are performed via the head driver 84 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 80 includes an image buffer memory 82, and image data, parameters, and other data are temporarily stored in the image buffer memory 82 when image data is processed in the print control unit 80. In FIG. 7, the image buffer memory 82 is shown in a mode associated with the print control unit 80, but it can also be used as the memory 74. Also possible is an aspect in which the print controller 80 and the system controller 72 are integrated and configured with a single processor.

  The head driver 84 drives the actuators of the print heads 12K, 12C, 12M, and 12Y for each color based on the print data given from the print control unit 80. The head driver 84 may include a feedback control system for keeping the head driving conditions constant.

  Various control programs are stored in a program storage unit (not shown), and the control programs are read and executed in accordance with instructions from the system controller 72. The program storage unit may be a semiconductor memory such as a ROM or EEPROM, or a magnetic disk. An external interface may be provided and a memory card or PC card may be used. Of course, you may provide several recording media among these recording media.

  The program storage unit may also be used as a recording unit (not shown) for operating parameters.

  As described with reference to FIG. 1, the print detection unit 24 is a block including a line sensor, reads an image printed on the recording paper 16, performs necessary signal processing, and the like to perform a print status (whether ejection is performed, droplet ejection And the detection result is provided to the print control unit 80.

  The print control unit 80 performs various corrections on the print head 50 based on information obtained from the print detection unit 24 as necessary.

  In the example shown in FIG. 1, the print detection unit 24 is provided on the print surface side, and the print surface is illuminated by a light source (not shown) such as a cold cathode tube disposed in the vicinity of the line sensor. Although the configuration is such that the reflected light is read by the line sensor, other configurations may be used in the implementation of the present invention.

  In the present embodiment, a full-line type print head has been exemplified, but the present invention is also applicable to a shuttle type head.

  FIGS. 8A and 8B show a modification of the ink chamber unit 53 shown in FIG. 8A and 8B, the same reference numerals are given to the same or similar parts as those in FIG. 4, and the description thereof is omitted.

  FIG. 4 shows a mode in which the piezoelectric active portion 58 is formed of a single-layer piezoelectric body, but FIG. 8A shows a mode in which the piezoelectric active portion 58 is formed of a three-layer laminated piezoelectric body. FIG. 8 (b) shows a mode (bimorph type) in which the piezoelectric active portion 58 is formed of two layers of laminated piezoelectric bodies.

  In the embodiment shown in FIG. 8 (a), the piezoelectric active portion 58 includes, in order from the common electrode 55A side, the first piezoelectric layer 55B, the inner layer individual electrode 57A, the second piezoelectric layer 55C, the inner layer common electrode 55D, and the third layer. The piezoelectric layer 55E and the individual electrode 57 are formed in a laminated structure.

  Further, on the opposite side of the third piezoelectric layer 55E from the inner common electrode 55D, a fourth piezoelectric layer 55F in which the individual electrode 57 and the deformation low-rigidity portion 59 are formed is formed.

  The common electrode 55A and the inner layer common electrode 55D are electrically connected, and the individual electrode 57 and the inner layer individual electrode 57A are electrically connected. As a connection method between the common electrode 55A and the inner layer common electrode 55D and a connection method between the individual electrode 57 and the inner layer individual electrode 57A, a known method such as a method using a through hole formed between the electrodes to be connected is used.

  In this way, in the piezoelectric active portion 58 formed of a multilayer piezoelectric body, the first piezoelectric layer 55B and the third piezoelectric layer 55E have the same polarization direction. On the other hand, the first piezoelectric layer 55B (third piezoelectric layer 55E) and the second piezoelectric layer 55C have different polarization directions.

  That is, the polarization direction of the first piezoelectric layer 55B is the direction from the inner layer individual electrode 57A to the common electrode 55A (the direction from the bottom to the top in FIG. 8 (a)). The polarization direction is a direction from the inner layer individual electrode 57A toward the inner layer common electrode 55D (in FIG. 8, a direction from top to bottom). The polarization direction of the third piezoelectric layer 55E is the direction from the individual electrode 57 toward the inner common electrode (in FIG. 8A, the direction from the bottom to the top).

  When a drive signal is applied to the individual electrode 57 of the piezoelectric active portion 58 shown in FIG. 8A, lateral distortion occurs in each piezoelectric layer depending on the direction of the applied voltage (acting electric field), and vibration occurs. The plate 56 can be displaced in the ink ejection direction and in the opposite direction.

  As shown in FIG. 8 (a), by making the piezoelectric active portion 58 a laminated structure, it is possible to generate energy larger than that of a single layer structure.

  8A illustrates an example in which a piezoelectric material is used for the diaphragm 56 and is integrally formed with the piezoelectric substrate 55. As shown in FIG. 4, the diaphragm 56 has a non-piezoelectric material such as a metal material. May be used. As in the pressure chamber 52 shown in FIG. 4, the pressure chamber 52 shown in FIG. 8A is made of a non-piezoelectric material except for the surface to which the diaphragm 56 is joined (formed).

Further, FIG. 8B shows a structure in which a first piezoelectric layer 55B and a second piezoelectric layer 55C, which are d ₃₁ mode piezoelectric bodies, are stacked. When the second piezoelectric layer 55C is driven to generate a strain that contracts in the lateral direction, and the second piezoelectric layer 55C generates a strain that contracts in the lateral direction, the piezoelectric active portion 58 made of the multilayered piezoelectric body moves in the vertical direction (in FIG. It functions as a bimorph piezoelectric body capable of obtaining a bending displacement that is convex in the direction.

  That is, the piezoelectric active portion 58 includes, in order from the individual electrode 57 side, the first piezoelectric layer 55B, the inner common electrode 55A, the second piezoelectric layer 55C, and the second individual electrode 57 ′ (the inner individual electrode layer 57A). It has a formed laminated structure. A predetermined ink-resistant treatment is performed on the pressure chamber 52 side of the individual electrode 57 (that is, the surface in contact with the ink). Of course, a material having ink resistance may be used for the individual electrode 57.

  Thus, when a bimorph type piezoelectric material is applied to the piezoelectric active portion 58, the diaphragm 56 can be omitted, and the laminated structure can be simplified.

  Next, application examples of the present embodiment will be described with reference to FIGS. 9 to 11.

  9A is a cross-sectional view showing the three-dimensional structure of the piezoelectric substrate 55, and FIG. 9B is a cross-sectional view showing the three-dimensional structure of the ink chamber unit 53 (9b-9b in FIG. 3A). It is sectional drawing which follows a line. 9 (a) and 9 (b), the same or similar parts as those in FIGS. 4 and 8 are denoted by the same reference numerals, and the description thereof is omitted.

  In the piezoelectric substrate 55 shown in FIGS. 9A and 9B, a plurality of low-rigidity portions 59 for deformation and low-rigidity portions 102 for preventing warpage are formed. The plurality of low-rigidity parts for deformation have the same configuration, and similarly, the plurality of low-rigidity parts for warpage prevention have the same configuration. Therefore, here, the plurality of low-rigidity parts for deformation and the low-rigidity parts for warpage prevention are representative. The deformation-use low-rigidity portion 59 and the warpage-preventing low-rigidity portion 102 will be described below.

  Inside the piezoelectric substrate 55, a low rigidity portion for warping prevention 102 is provided at a position symmetrical to a plane that bisects the thickness of the deformation low rigidity portion 59 and the piezoelectric substrate 55 into approximately two equal parts.

  That is, in the cross section shown in FIG. 9 (a), the low-rigidity portion 102 for preventing warpage is located at a line-symmetrical position (a position symmetrical to the thickness direction) with respect to the line 104 that bisects the thickness direction of the piezoelectric substrate 55. Is provided.

  In other words, the deformable low-rigidity portion 59 and the warpage-preventing low-rigidity portion 59 having substantially the same shape and substantially the same size so that the distance from the line 104 that bisects the thickness direction of the piezoelectric substrate 55 is substantially equal. 102. A line 104 that bisects the thickness direction of the piezoelectric substrate 55 represents a plane that bisects the thickness of the piezoelectric substrate 55 in the cross-sectional views of FIGS. 9 (a) and 9 (b). .

  On the other hand, an individual electrode 57 is formed on the surface of the deforming low-rigidity portion 59 on the side opposite to the warpage-preventing low-rigidity portion 102. Of course, an electrode layer corresponding to the individual electrode 57 may be provided on the warpage preventing low-rigidity portion 102 so that the deforming low-rigidity portion 59 and the warpage preventing low-rigidity portion 102 have the same shape and the same structure.

  In this example, the warp prevention low rigidity portion 102 having substantially the same shape and the same size as the deformation low rigidity portion 59 is shown, but the warpage prevention low rigidity portion 102 is different in shape from the deformation low rigidity portion 59 and different. You may form in a size and you may provide the low rigidity part 102 for several curvature prevention with respect to the low rigidity part 59 for a deformation | transformation. Further, one warp preventing low rigidity portion 102 may be provided for the plurality of deformation low rigidity portions 59.

  That is, in order to prevent warping during firing of the piezoelectric substrate, the warp preventing low rigidity portion 102 is provided corresponding to the deformation low rigidity portion 59 so that the rigidity of the entire piezoelectric substrate 55 is substantially uniform. .

  9 (b) shows a common electrode 55A, a diaphragm 56, and a flow path member on the piezoelectric substrate 55 provided with the low rigidity portion 59 for deformation and the low rigidity portion 102 for preventing warpage shown in FIG. 9 (a). The state where 52A and the nozzle plate 51A are joined is shown.

  A piezoelectric substrate 55 shown in FIG. 9B is an electrode-divided piezoelectric body in which a plurality of individual electrodes are provided on one piezoelectric substrate, and a drive signal is given to each individual electrode to drive it as a plurality of piezoelectric bodies.

  In the piezoelectric substrate 55 formed as shown in FIG. 9, it is possible to prevent warping that occurs in the firing process during manufacturing. Details of the manufacturing process of the piezoelectric substrate 55 will be described later.

  10 (a) and 10 (b) show a modification of the embodiment shown in FIGS. 9 (a) and 9 (b).

  A piezoelectric substrate 55 shown in FIG. 10A has a common electrode 55A and a diaphragm 56 made of a piezoelectric material formed integrally with the piezoelectric substrate 55 shown in FIG. A thickness direction that is symmetrical with respect to a line 104 that bisects the thickness directions of the interference-preventing low-rigidity portion 110 and the piezoelectric substrate 55 in the thickness direction of the low-rigidity prevention portion 110 and the piezoelectric substrate 55. Are provided with a low-rigidity portion 112 for preventing warpage and interference.

  The interference preventing low-rigidity portion 110 is a part of the diaphragm 56 excluding a region corresponding to the piezoelectric active portion 58 shown in FIGS. 4 and 8 (that is, a region where the deformation low-rigidity portion 59 is provided). It is provided in the non-deformation region 116 other than the deformation region 114 that deforms according to the strain of the piezoelectric active portion 58. Further, the interference preventing low rigidity portion 110 and the warpage interference preventing low rigidity portion 112 have the same shape and the same size.

  FIG. 10B shows an ink chamber unit 53 using the piezoelectric substrate 55 shown in FIG.

  In the piezoelectric substrate 55 formed as shown in FIG. 10, it is possible to prevent the warpage that occurs in the baking process at the time of manufacture, and to alleviate the adjacent crosstalk that occurs during ink ejection.

  That is, the interference preventing low-rigidity portion 110 contributes to alleviating adjacent crosstalk during ink ejection, and the warpage interference preventing low-rigidity portion 112 can be warped by providing the interference preventing low-rigidity portion 110. Contributes to the prevention of

  FIG. 11 shows an aspect in which the piezoelectric substrate 55 is provided with a groove 120 for relaxing adjacent crosstalk.

  As shown in FIG. 11, the groove 120 is provided in the piezoelectric inactive portion 122 where the individual electrode 57 adjacent to at least one of both sides of the piezoelectric active portion 58 is not disposed, and after the piezoelectric substrate 55 is fired. It is formed by processing means such as cutting.

  The piezoelectric inactive part 122 includes a region not sandwiched between the individual electrode 57 and the common electrode 55A to which a drive signal is applied, and is formed so as to surround the periphery of the piezoelectric active part 58. That is, the piezoelectric inactive portion 122 includes a region of the piezoelectric substrate 55 that does not produce a piezoelectric effect.

  In this example, an example in which two grooves 120 are formed between adjacent piezoelectric active portions is illustrated, but of course, the number of grooves 120 may be one or three or more. Further, as shown in FIG. 11, the shape of the groove 120 may be a substantially rectangular (quadrangle) cross-sectional shape, or may be another shape such as a hole shape.

  As described above, since the groove 120 for reducing the adjacent crosstalk is formed by processing means such as cutting after the piezoelectric substrate 55 is fired, the thickness direction inside the piezoelectric substrate 55 is prevented in order to prevent the piezoelectric substrate 55 from warping. It is not necessary to provide a groove corresponding to the groove 120 at a target position (a position symmetrical with respect to the line 104 that bisects the thickness direction of the piezoelectric substrate 55).

  4 and FIG. 8, the deformation low rigidity portion 59 shown in FIG. 9, the warpage prevention low rigidity portion 102, and the interference prevention low rigidity portion 110 shown in FIG. In addition, the low rigidity portion 112 for preventing warpage interference and the groove 120 shown in FIG. 11 may be filled with a material that is less synthetic than the piezoelectric body.

[Print head manufacturing method]
Next, a method for manufacturing the print head 50 according to the present invention will be described in detail.

  A method of manufacturing the print head 50 will be described in the order of the steps with reference to FIGS.

  FIG. 12A shows a green sheet laminating process.

  In the green sheet lamination step, green sheets (piezoelectric material) 200 and inner layer electrodes 202 made of an electrode material are alternately laminated to form a laminate 204 of the piezoelectric material and the electrode material. Note that the laminate 204 may be formed by screen printing instead of laminating green sheets, or the laminate 204 may be formed by a sol-gel method.

  FIG. 12B shows the binder printing process.

  A binder resin 210 is formed on the portion where the low rigidity portion 59 for deformation shown in FIGS. 4 and 8 and the low rigidity portion 59 for deformation shown in FIGS. 9 to 11 are formed. When a liquid binder is used for the binder resin 210, a printing method is used. On the other hand, when a solid binder is used, the solid binder may be applied on the green sheet by a photolithography process.

  The binder material used in this step is a binder material used for green sheets and printing pastes, and acrylic, polyurethane, nylon, Teflon, silicon, and the like are conceivable.

  Further, in the first green sheet laminating step shown in FIG. 12 (a), the portion for forming the low rigidity portion 102 for preventing warpage shown in FIG. 9 and the low rigidity portion 112 for preventing warpage interference shown in FIG. Also, the binder resin 210 is printed.

  FIG. 12C shows the individual electrode forming process.

  In the binder printing process shown in FIG. 12 (b), an electrode material to be the individual electrode 57 is laminated on the opposite side of the binder resin 210 printed on the green sheet from the green sheet.

  FIG. 12 (d) shows a second green sheet laminating step.

  A green sheet 200 is further laminated on the surface of the laminate 204 where the binder resin 210 and the individual electrode 57 are formed.

  FIG. 12 (e) shows a pressurizing step and a degreasing / firing step.

  The laminate 204 that has undergone the second green sheet laminating step is pressure-molded in the thickness direction (vertical direction in FIG. 12), and then degreased and fired.

  In the firing step, heat of 600 ° C. to 1300 ° C. is applied to the laminate 204, the piezoelectric material is fired, and the binder resin 210 is burned away. In this step, the binder resin 210 is burned out, so that voids (cavities) serving as the deformation low-rigidity portions 59 (deformation low-rigidity portions 59) are formed between the green sheets (piezoelectric layers).

  In this step, even when the binder resin 210 remains without being completely burned out, the remaining binder resin acts as a low-rigidity body and can increase the discharge force (generated pressure). Plays a role in preventing vibration (damper effect) and preventing damage (improving reliability).

  FIG. 12F shows a common electrode forming process.

  Through the degreasing and firing steps shown in FIG. 12 (e), a common electrode 55A made of an electrode material is formed on the upper surface side of the piezoelectric substrate 55 on which the low rigidity portion 59 for deformation is formed. As a method of forming the common electrode 55A on the piezoelectric substrate 55, a known thin film forming technique such as vapor deposition or sputtering can be used.

  FIG. 12 (g) shows the diaphragm joining process.

  A diaphragm 56 is joined to the common electrode 55A formed by the common electrode forming step shown in FIG.

  When the diaphragm 56 is formed using a piezoelectric material, the common electrode forming process and the diaphragm joining process are omitted.

  FIG. 12 (h) shows the flow path member joining step.

  When the diaphragm 56 is joined to the piezoelectric substrate 55 by the diaphragm joining step shown in FIG. 12 (f), a flow path member 52A is formed on the surface of the diaphragm 56 opposite to the piezoelectric substrate 55. .

  FIG. 12 (i) shows the nozzle plate joining step.

  When the flow path member 52A is joined by the flow path member joining step shown in FIG. 12 (f), the nozzle plate 51A is joined to the surface of the flow path member 52A opposite to the diaphragm 56.

  Bonding of the common electrode 55A and the diaphragm 56, bonding of the diaphragm 56 and the flow path member 52A, and bonding of the flow path member 52A and the nozzle plate 51A may be performed using an adhesive, The joining method may be used.

  The wiring of the individual electrode 57 and the wiring of the electrode layer in the inner layer of the piezoelectric substrate 55 may be drawn out from the deformation low rigidity portion 59 (hole) using a via. Further, instead of the individual electrode forming step shown in FIG. 12 (c), an electrode layer is formed on the entire surface of the binder side of the green sheet 200 to be laminated in the second green sheet laminating step, and this electrode layer is used as a common electrode. The individual electrodes may be formed on the diaphragm bonding surface side of the piezoelectric substrate after the piezoelectric substrate 55 is fired.

  The inner layer electrode layer 202 inside the piezoelectric substrate 55 is wired to the common electrode 55A or the individual electrode 57 by a wiring process (not shown), and functions as the inner layer common electrode 55D and the inner layer individual electrode 57A shown in FIG. .

  When the interference preventing low-rigidity portion 110 shown in FIG. 10 is formed, the binder resin 210 is disposed at a position where the interference preventing low-rigidity portion 110 is formed after the electrode layer to be the common electrode 55A is formed. Is done.

  When the groove 120 shown in FIG. 11 is formed, a groove processing step is provided after the degreasing / firing step shown in FIG.

  4 and 8, the deformation low rigidity portion 59 shown in FIG. 9, the warpage prevention low rigidity portion 102, the interference prevention low rigidity portion 110 shown in FIG. 10, A filling process for filling the material of the low rigidity part 112 for preventing warpage interference and the groove 120 shown in FIG.

  The print head 50 configured as described above uses a piezoelectric substrate 55 in which piezoelectric materials and electrode materials are alternately laminated to form a piezoelectric body that serves as an ejection force application unit for ink ejected from the print head 50. In addition, since the binder resin 210 that is at least partially burned off when the piezoelectric body is fired, the deformation low-rigidity portion 59 such as a hole is provided on the side opposite to the pressure chamber 52 of the piezoelectric active portion 58 (piezoelectric actuator). The piezoelectric active portion 58 (piezoelectric active portion) having a thickness smaller than that of the piezoelectric substrate 55 can be formed.

  Therefore, since the piezoelectric substrate 55 has a thickness, it is possible to ensure handling even when a large-area print head is manufactured. Further, the piezoelectric active portion 58 (piezoelectric actuator) that is sufficiently thin compared to the thickness of the piezoelectric substrate 55. ), A post-process such as polishing or sandblasting is not necessary.

  Inside the piezoelectric substrate 55, a position symmetrical with respect to the target position in the thickness direction of the piezoelectric substrate 55 of the low rigidity portion 59 for deformation (a line 104 that bisects the thickness direction of the piezoelectric substrate 55 substantially equally). ) Is provided with the low-rigidity portion 102 for preventing warpage, it is possible to prevent warpage caused by heat during firing of the piezoelectric substrate 55.

  In this embodiment, a print head used in an inkjet recording apparatus is exemplified as a droplet discharge head. However, the present invention is not limited to liquids (water, chemicals) on a discharge medium such as a wafer, a glass substrate, or an epoxy substrate. In addition, the present invention can also be applied to a discharge head used in a liquid discharge apparatus that forms shapes such as images, circuit wirings, and processing patterns by discharging a resist and a processing liquid.

1 is a basic configuration diagram of an ink jet recording apparatus equipped with a print head according to an embodiment of the present invention. FIG. 1 is a plan view of the main part around the printing of the ink jet recording apparatus shown in FIG. Plane perspective view showing structural example of print head Sectional drawing which follows the 4-4 line in FIG. FIG. 3 is an enlarged view showing the nozzle arrangement of the print head shown in FIG. 1 is a conceptual diagram showing the configuration of an ink supply system in an ink jet recording apparatus equipped with a print head according to the present embodiment. Main part block diagram which shows the system configuration | structure of the inkjet recording device carrying the printing head which concerns on this embodiment. Sectional drawing which shows the three-dimensional structure of the modification of the ink chamber unit shown in FIG. The figure which shows the modification of the piezoelectric material board and ink chamber unit which were shown in FIG.4 and FIG.8. FIG. 9 is a diagram showing an application example of the piezoelectric substrate and the ink chamber unit shown in FIG. The figure which shows the other application example of the piezoelectric material board shown in FIG. The figure explaining the manufacturing process of the print head concerning this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 50 ... Print head, 52 ... Pressure chamber, 52A ... Flow path member, 55 ... Piezoelectric substrate, 55A, 55D ... Common electrode, 56 ... Diaphragm, 57, 57A ... Individual electrode, 58 ... Piezoelectric Active part, 59, 100, 102, 110, 112 ... low rigidity part, 120 ... groove, 210 ... binder resin

Claims (14)

An ejection head that ejects liquid droplets onto a medium to be ejected,
A piezoelectric substrate including a piezoelectric active portion in which electrode materials and piezoelectric materials are alternately stacked and a strain is generated when an electric field is applied;
A pressure chamber that is laminated and bonded to the piezoelectric substrate and contains a liquid to be discharged onto the discharge target medium, and a flow path member including a liquid flow path when the liquid is supplied to the pressure chamber;
With
The ejection head according to claim 1, wherein the piezoelectric substrate has a deforming low-rigidity portion in which a piezoelectric material is missing inside the piezoelectric substrate opposite to a surface where the pressure chamber of the piezoelectric active portion is laminated and bonded.   The ejection head according to claim 1, wherein the piezoelectric active portion includes a bimorph piezoelectric body formed by laminating two layers of piezoelectric bodies.   The ejection head according to claim 1, further comprising a diaphragm that deforms according to distortion of the piezoelectric active portion between the piezoelectric substrate and the flow path member.   4. The ejection head according to claim 3, wherein the diaphragm is formed of a material including a piezoelectric member and is integrally formed with the piezoelectric substrate.   5. The ejection head according to claim 1, wherein the flow path member is formed of a material including a non-piezoelectric member. The ejection head according to claim 1, wherein the piezoelectric active portion includes a piezoelectric body that generates a d ₃₁ mode displacement.   The piezoelectric substrate is provided with the low rigidity portion for deformation inside the piezoelectric substrate and the low rigidity portion for warpage prevention in which a piezoelectric material is missing at a position symmetrical to the thickness direction of the piezoelectric substrate. The ejection head according to any one of claims 1 to 6, wherein   The piezoelectric substrate includes an interference-preventing low-rigidity portion in which a piezoelectric material is missing in a piezoelectric inactive portion that does not generate distortion even when an electric field inside the piezoelectric substrate is applied. The discharge head according to any one of 7.   9. The piezoelectric substrate includes a low-rigidity portion for preventing warping at a position symmetrical to the thickness direction of the piezoelectric substrate of the low-rigidity portion for preventing interference inside the piezoelectric substrate. The discharge head described. A method for manufacturing a discharge head that discharges droplets onto a discharge medium,
A piezoelectric substrate forming step in which an electrode material and a piezoelectric material are alternately laminated and a piezoelectric substrate including a piezoelectric active portion that generates distortion when an electric field is applied;
A bonding step of laminating and bonding a pressure chamber for storing a liquid to be discharged onto the discharge target medium on the piezoelectric substrate and a flow path member in which a liquid flow path is formed when the liquid is supplied to the pressure chamber;
Including
The piezoelectric substrate forming step includes a deforming low-rigidity portion forming step of forming a deforming low-rigidity portion in which the piezoelectric material is missing inside the piezoelectric substrate on the side opposite to the pressure chamber of the piezoelectric active portion. A discharge head manufacturing method. In the deforming low-rigidity portion forming step, the deforming low-rigidity portion forming a deforming low-rigidity portion removing layer from which at least a part including a member having rigidity lower than that of the piezoelectric material is removed is formed on the piezoelectric substrate. A removal layer forming step;
A piezoelectric layer laminating step of laminating a piezoelectric material on the deforming low rigidity portion removing layer formed by the deforming low rigidity portion removing layer; and
When the piezoelectric substrate after the piezoelectric layer laminating step is heated to fire the piezoelectric substrate, at least a part of the low rigidity portion removing layer for deformation is removed and the piezoelectric material is missing. A heating step in which a low-rigidity part is formed;
The method of manufacturing an ejection head according to claim 10, comprising: The piezoelectric substrate includes a member having a rigidity lower than that of the piezoelectric material at a symmetrical position in the thickness direction in which the deformation low rigidity portion removing layer and each layer of the piezoelectric substrate of the piezoelectric substrate are laminated. Including a low-rigidity removing layer forming step for preventing warpage, which forms a low-rigidity removing layer for preventing warping from which at least a part is removed,
The discharge head manufacturing method according to claim 11, wherein at least a part of the warpage preventing low-rigidity removing layer is removed by the heating step to form a warpage-preventing low-rigidity portion in which a piezoelectric material is missing. .   A vibration plate joining step of joining a vibration plate formed of a material containing a non-piezoelectric material between the piezoelectric substrate and the flow path member to the piezoelectric substrate after the heating step. Item 13. The discharge head manufacturing method according to Item 10, 11 or 12. By post-processing after the ejection force applying member forming step, interference prevention is achieved by forming a low-rigidity portion for preventing interference in which a piezoelectric material is missing in a piezoelectric inactive portion that does not cause distortion even when an electric field inside the piezoelectric substrate is applied. The method for manufacturing an ejection head according to claim 10, further comprising a low-rigidity portion forming step.

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