Patent Application
20120003902
The present invention relates to a method for manufacturing a droplet discharge head, which discharges a droplet of, for example, a liquid containing DNA, a liquid material, a liquid fuel, and the like.
Conventionally, a ceramic layered body having in its inside a hollow cavity, which is, for example, a pressure chamber for pressurizing a liquid, has been known. Such a ceramic layered body is used in a wide variety of fields including, for example, an apparatus for producing a DNA chip, an “actuator for injecting a fluid” such as a fuel injection device, an actuator for an ink jet printer, a solid-oxide fuel cell (SOFC), a switching device, a sensor, and so on (refer to Patent document 1).
Generally, such a ceramic layered body is manufactured according to procedures described below.
(1) Ceramic green sheets are prepared.
(2) A through hole having a predetermined shape is formed in the ceramic green sheet by punching using “a mold and a die”.
(3) The ceramic green sheets each having the formed through hole and the ceramic green sheets each having no through hole are stacked (layered).
(4) A plurality of the layered green sheets are fired to be united (integrated).
However, punching using a mold and a die forms the through hole by sheering. Accordingly, when the ceramic green sheet is punched through, a large force is applied to the ceramic green sheet. As a result, a fracture surface becomes rough, or a burr and a crack may be generated. Especially, when the pressure chamber (cavity) is miniaturized, the deformation, the burr, the crack, and the like may cause great adverse effects on a shape accuracy of the pressure chamber (cavity). Further, “the mold and the die” need to have hardness to endure the punching, and therefore, they are formed of a material having high hardness. Since it is difficult to produce a miniaturized mold and a miniaturized die using the material having high hardness, there is a limit on miniaturizing the pressure chamber (cavity).
The present invention is made to cope with the problems described above. That is, one of the objects of the present invention is to provide a “method for manufacturing a droplet discharge head”, which allows to manufacture a droplet discharge head having an excellent shape accuracy, even if the pressure chamber is miniaturized, a distance between the pressure chambers adjacent to each other is short, and so on.
One of the methods for manufacturing a droplet discharge head (hereinafter, referred to as a “present manufacturing method”) according to the present invention in order to achieve the object described above is a manufacturing method for manufacturing a droplet discharge head including a “droplet discharge head body comprising a pressure chamber for retaining/storing liquid and a nozzle section communicating with the pressure chamber”.
The present manufacturing method includes (1) slurry preparing step, (2) mold preparing step, (3) porous plate preparing step, (4) head-body-before-fired forming step, and (5) firing step.
The slurry preparing step is a step for preparing a slurry including ceramic powders, a solvent (resolvent) for the ceramic powders, and an organic material.
The mold preparing step is a step for preparing a mold including a base portion having at least one flat (plain) surface, and a convexity portion having a convexity which stands (is held upright, or erects) from the flat surface of the base portion and has the substantially same shape as a “liquid chamber including the pressure chamber and the nozzle section”. A molding surface of the mold is composed of a portion of the flat surface of the base portion at which the convexity portion does not exist, and a surface of the convexity portion.
The porous plate preparing step is a step for preparing a porous plate, having at least one flat (plain) surface, through which gases can pass.
The head-body-before-fired forming step is a step for forming a droplet discharge head body-before-fired (droplet discharge head body which has not been fired) by placing the porous plate and the mold in such a manner that the porous plate and the mold are opposed to each other while the slurry is maintained (or kept, held) between the flat surface of the porous plate and the molding surface of the mold, and drying the slurry through having the solvent included in the slurry permeate into fine pores of the porous plate.
The firing step is a step for forming a droplet discharge head body-after-fired (droplet discharge head body which has been fired) by firing the droplet discharge head body-before-fired.
As long as the slurry preparing step, the mold preparing step, and the porous plate preparing step are performed before the head-body-before-fired forming step, these steps can be performed in any order.
According to the present manufacturing method, the pressure chamber is formed by forming the slurry in the mold. Therefore, the droplet discharge head having an excellent shape accuracy can be manufactured, even when the pressure chamber is miniaturized, the distance between the pressure chambers adjacent to each other is short, and so on.
Further, according to the present manufacturing method, the nozzle section is also formed by forming the slurry in the mold. Therefore, the surface of the nozzle section is smooth and has no burrs or the like, as compared with the case in which the nozzle section is formed by punching using a mold and a die. As a result, the droplet discharge head capable of stably discharging droplets can be provided.
According to the present manufacturing method, the droplet discharge head body is formed (made, produced) using a single mold. It is therefore unnecessary to join two compacts to form the droplet discharge head body, and further unnecessary to join a metal plate, or the like, which has a through hole, to the nozzle section of the droplet discharge head body, for example. Thus, the steps can be simplified. Further, it is unnecessary to pressure bond or join two compacts while aligning those two compacts in order to form the droplet discharge head body. Therefore, the droplet discharge head having a desired shape can easily be manufactured.
Further, it is preferable that the head-body-before-fired forming step include:
polishing-before-demolding step for polishing, in a state in which (while) a compact-after-dried formed of the slurry which was dried in the mold is maintained (kept, held) in the mold, an exposed surface of the compact-after-dried (i.e., surface of the compact which contacted with the flat surface of the porous plate), to thereby remove (eliminate) a remnant membrane (remained residual film) of the compact-after-dried to complete (form) a portion corresponding to the nozzle section; and
demolding step for releasing (separating, removing) the mold from the compact-after-dried from which the remnant membrane was removed.
According to the method described above, polishing the compact-after-dried is preformed in a state in which a “hollow cavity portions of the compact-after-dried” which will become the pressure chamber and the nozzle section are buried in (or filled with) the (portion of the) mold, grinding sludge and/or abrasive grains do not enter into the hollow cavity portions. It is therefore unnecessary to include such a step for removing (eliminating) the grinding sludge and/or abrasive grains. Consequently, the manufacturing method as a whole can be simplified. Furthermore, the “compact-after-dried” to be polished is the compact which has not been fired yet, and thus, it has lower hardness than a compact which has been fired (fired body). Accordingly, a polishing rate can be increased, and therefore, the polishing can be completed within short time.
In addition, the polishing-before-demolding step may be a step for polishing the exposed surface of the compact-after-dried by holding (retaining) the mold, maintaining (keeping, holding) the compact-after-dried, at an side opposite to the molding surface by a polishing retainer (holding tool for polishing), and pressing the exposed surface of the compact-after-dried against a polishing plate while the polishing retainer is reciprocated in a direction parallel to the flat surface of the base portion.
According to the method described above, since the polishing is performed with using the portion of the mold opposite to the molding surface (the surface opposite to the molding surface, back surface of the mold) as a reference, a flatness of the exposed surface of the compact-after-dried (surface to be polished) can be easily ensured.
Meanwhile, the present manufacturing method may further include:
special blast processing using elastic body step, performed after the firing step, for projecting (injecting) polishing agents, each including a plurality of abrasive grains being smaller than and fixed to an elastic base material, to the droplet discharge head body-after-fired to thereby remove (eliminate) the remnant membrane (remained residual film) of the droplet discharge head body-after-fired to complete/finish a portion corresponding to the nozzle section.
According to the blast processing described above, even when the droplet discharge head body-after-fired has small undulation/warpage caused by being fired, the droplet discharge head body-after-fired can be polished by a constant amount according to the undulation/warpage. Therefore, a diameter of a tip portion of the nozzle section (i.e., opening for droplet discharge, which is formed on the surface of the head body-after-fired by the nozzle section) can be controlled within a desired range. In addition, a surface roughness in the vicinity of the opening(s) for droplet discharge can be uniform, and therefore, a hydrophilicity of the lower surface of the droplet discharge head body in the vicinity of the opening(s) for droplet discharge to a liquid can be uniform. Accordingly, the droplet discharge head capable of discharging the droplets stably can be manufactured.
The above and other objects, features and associated advantages of the present invention will be easily understood better from the following description of each of embodiments according to the present invention with reference to the following drawings.
Next will be described a method for manufacturing a droplet discharge head according to embodiment of the present invention with reference to the drawings. It should be noted that performing order of the steps described below can be changed as long as there is no inconsistency.
First, a schematic structure will be described of a droplet discharge head 10 manufactured by a “method for manufacturing a droplet discharge head” according to an embodiment of the present invention.
As shown in (A) and (B) of
The head body 20 is formed of ceramic. The head body 20 has a rectangular parallelepiped shape having sides, each being parallel to one of X, Y and Z axes orthogonal to each other. That is, as shown (A) of
A plurality (in the example shown in
More specifically, the groove section 21a has “long sides, each extending along the X-axis, and short sides, each extending along the Y-axis”, in a plan view. One of ends of the long side extending along the X-axis, of the groove section 21a is positioned at a position close to an X-axis negative direction end of the head body 20. The other one of the ends of the long side, extending along the X-axis, of the groove section 21a is positioned at a substantially center portion of the head body 20 in an X-axis direction. A bottom surface of the groove section 21a is a flat (plain) surface located at a substantially center portion of the head body 20 in a thickness direction of the head body 20. That is, a depth (height) of the groove section 21a is about a half of the thickness (height) of the head body 20.
In the head body 20, nozzle sections 21b are formed. Each of the nozzle sections 21b are provided at a position close to an X-axis negative direction end of the bottom surface of the groove section 21a. Each of the nozzle sections 21b has an inverted circular truncated cone shape (or a cylindrical shape). Each of the nozzle sections 21b provides a communication passage between the respective bottom surface of each of the groove sections 21a and the lower surface 20a of the head body 20. Thus, each of the nozzle sections 21b forms (provides) a droplet discharge hole.
A concave section 22a is formed for constituting (forming) a liquid storage chamber (ink tank chamber) 22 at the upper portion of the head body 20. The concave section 22a has a substantially rectangular parallelepiped shape.
More specifically, the concave section 22a has “long sides, each extending along the X-axis, and short sides, each extending along the Y-axis”, in a plan view. One of ends of the long side, extending along the X-axis, of the concave section 22a is positioned at a position close to an X-axis positive direction end of the head body 20. The other one of the ends of the long side, extending along the X-axis, of the concave section 22a is positioned at the substantially center portion of the head body 20 in the X-axis direction, and is apart from the other one of the ends of the long side, extending along the X-axis, of the groove section 21a at a predetermined distance. One of the ends of the short side, extending along the Y-axis, of the concave section 22a is positioned at a portion in the side of a Y-axis positive direction as compared to a Y-axis positive direction end of the short side of the groove section 21a which is positioned at the Y-axis positive direction end of the plurality of the groove sections 21a. The other one of the ends of the short side, extending along the Y-axis, of the concave section 22a is positioned at a portion in the side of Y-axis negative direction as compared to a Y-axis negative direction end of the short side of the groove section 21a which is positioned at the Y-axis negative direction end of the plurality of the groove sections 21a. A bottom surface of the concave section 22a is a flat (plain) surface located at the substantially center portion of the head body 20 in the thickness direction of the head body 20. That is, a depth (height) of the concave section 22a is the same as the depth (height) of the groove section 21a.
A plurality (in the example shown in
More specifically, each of the groove sections 23a has “long sides, each extending along the X-axis, and short sides, each extending along the Y-axis”, in a plan view. One of ends of the long side extending along the X-axis, of each of the groove sections 23a is extended to the “short side extending along the Y-axis” of one of the groove sections 21a, located at the X-axis positive direction end of the one of the groove sections 21a. The other one of the ends of the long side, extending along the X-axis, of each of the groove sections 23a is extended to the “short side extending along the Y-axis” of the concave section 22a, located at the X-axis negative direction end of the concave section 22a. A length of the short side extending along the Y-axis of each of the groove section 23a is smaller than a length of the short side extending along the Y-axis of each of the groove sections 21a. Each one of the groove sections 23a provides a communication passage between each one of the groove sections 21a and the concave section 22a. A bottom surface of each of the groove sections 23a is a flat (plain) surface located at the substantially center portion of the head body 20 in the thickness direction of the head body 20. That is, a depth (height) of the groove section 23a is the same as the depth (height) of the groove section 21a.
The vibration plate 30 is a thin plate formed of a ceramic, having a small thickness (height) along the Z-axis direction. The vibration plate 30 is easily deformable. A shape of the vibration plate 30 in a plan view is a rectangle. A position of an X-axis positive direction end of the vibration plate 30 substantially coincides with the position of the X-axis positive direction ends of the groove sections 21a. A position of an X-axis negative direction end of the vibration plate 30 substantially coincides with the position of the X-axis negative direction end of the head body 20. “A Y-axis positive direction end and a Y-axis negative direction end” of the vibration plate 30 substantially coincide with “the Y-axis positive direction end and the Y-axis negative direction end” of the head body 20, respectively. The vibration plate 30 is disposed so as to contact with an upper surface of the head body 20. Accordingly, the vibration plate 30 covers upper portions of all of the groove sections 21a. Consequently, each of the pressure chambers 21 is formed (defined) by the bottom surface and side surfaces of each of the groove sections 21a together with a lower surface of the vibration plate 30.
The liquid storage chamber cover member 40 is a plate formed of a ceramic, having a thickness (height) along the Z-axis direction. A shape of the liquid storage chamber cover member 40 in a plan view is a rectangle. A position of an X-axis positive direction end of the liquid storage chamber cover member 40 substantially coincides with the position of the X-axis positive direction ends of the head body 20. A position of an X-axis negative direction end of the liquid storage chamber cover member 40 coincides with the position of the X-axis positive direction end of the vibration plate 30. That is, the X-axis negative direction end of the liquid storage chamber cover member 40 contacts with the X-axis positive direction end of the vibration plate 30. “A Y-axis positive direction end and a Y-axis negative direction end” of the liquid storage chamber cover member 40 substantially coincide with “the Y-axis positive direction end and the Y-axis negative direction end” of the head body 20, respectively. The liquid storage chamber cover member 40 is disposed so as to contact with the upper surface of the head body 20. Accordingly, the liquid storage chamber cover member 40 covers an upper portion of the concave section 22a. Consequently, the liquid storage chamber 22 is formed (defined) by the bottom surface and side surfaces of the concave section 22a together with a lower surface of the liquid storage chamber cover member 40.
Further, the liquid storage chamber cover member 40 covers upper portions of all of the groove sections 23a. Consequently, each of the liquid flow holes 23 is formed (defined) by the bottom surface and side surfaces of each of the groove sections 23a together with the lower surface of the liquid storage chamber cover member 40. Each one of the liquid flow holes 23 provides a liquid passage which allows a liquid to flow (pass) between each one of the pressure chambers 21 and the liquid storage chamber 22.
A liquid supply through hole 40a is formed in the liquid storage chamber cover member 40. The liquid supply through hole 40a is provided at a substantially central portion of the liquid storage chamber cover member 40 in a plan view. The liquid supply through hole 40a provides a liquid passage which allows a liquid to flow (pass) between an exterior of the droplet discharge head body 20 and the liquid storage chamber 22.
It should be noted that, in place of the liquid storage chamber cover member 40, the vibration plate 30 may cover not only the upper portions of all of the concave portions 21a but also the upper portions of concave portion 22a and all of the groove sections 23a.
Each of a plurality of the piezoelectric elements 50 has “long sides, each extending along the X-axis, and short sides, each extending along the Y-axis”, in a plan view. A shape of each of the piezoelectric elements 50 substantially coincides with the shape of each of the pressure chambers 21 (and thus, coincides with each of the groove sections 21a), in a plan view. Each of a plurality of the piezoelectric elements 50 is formed so as to oppose to each of a plurality of the pressure chambers 21 to sandwich the vibration plate 30 therebetween.
In the thus configured droplet discharge head 10, a liquid (e.g., ink) is supplied from the exterior of the droplet discharge head 10 to the liquid storage chamber 22 through the liquid supply through hole 40a. The liquid in the liquid storage chamber 22 is supplied to each of the pressure chambers 21 through each of the liquid flow holes 23. When the piezoelectric element 50 is deformed by means of an electric power supplied from an unillustrated power/drive source, the vibration plate 30 deforms. Consequently, the liquid in the pressure chamber 21 is pressurized (compressed) to thereby be discharged as a droplet from the lower surface 20a of the droplet discharge head 10 through the “nozzle section 21b providing a communication passage between the pressure chamber 21 to the exterior”. That is, the liquid is discharged from the opening for discharging a liquid, the opening being a lower end of the nozzle section 21b formed on the lower surface 20a.
The manufacturing method will next be described for each of steps.
Firstly, a slurry SL is prepared. The slurry SL consists of ceramic powders serving as particles of a main raw material, a solvent for the ceramic powders, an organic material, and a plasticizing agent. A ratio by weight of those is, for instance, the ceramic powder:the solvent:the organic material:the plasticizing agent=100:50-100:5-10:2-5. In the present example, the ceramic powders are made of alumina, zirconia, and so on. The solvent is made of toluene, isopropyl alcohol, and so on. The organic material is made of polyvinyl butyral, and so on. The plasticizing agent is made of phthalate series butyl, and so on. Each of the materials and the weight ratio are not limited thereto. It should be noted that it is preferable that a viscosity of the slurry be, for example, 0.1-100 Pa·sec.
A mold (a pressing mold, a stamper) 100 shown in (A) to (C) of
The base portion 101 is a substantially flat plate. Therefore, the base portion 101 comprises at least one flat (plain) surface 101u.
The convexity portions for forming pressure chambers 102 stand (are held upright, or erect) from the flat surface 101u. The convexity portions for forming pressure chambers 102 have the substantially same shape as a shape defined by “a plurality of the groove sections 21a, the concave section 22a, and a plurality of the groove sections 23a” described above. That is, the convexity portions for forming pressure chambers 102 have the substantially same shape as a shape defined by “a plurality of the pressure chambers 21, the liquid storage chamber 22, and a plurality of the liquid flow holes 23”. Thus, the convexity portions for forming pressure chambers 102 are a convexity portion including convexities, each having the substantially same shape as the shape of each of the pressure chambers 21 that are arranged parallel to each other.
Each of the convexity portions for forming nozzle sections 103 stands (is held upright, or erects) from a top surface 102a of each of the convexity portions for forming pressure chambers 102. Each of the convexity portions for forming nozzle sections 103 has the substantially same shape as the shape of each of the nozzle sections 21b shown in
The frame portion 104 stands (is held upright, or erects) from the flat surface 101u at an entire outer circumference of the base portion 101. A shape defined by inner side surfaces of the frame portion 104 is the substantially same as the shape defined by the outer circumference of the head body 20 shown in
A molding surface of the mold 100 is composed of a portion (surface) of the flat surface 101u of the base portion 101 where “the convexity portions for forming pressure chambers 102 and the frame portion 104” do not exist, a portion (surfaces) of the surfaces of the convexity portions for forming pressure chambers 102 where the convexity portions for forming nozzle sections 103 do not exist, surfaces of the convexity portions for forming nozzle sections 103, and the inner side surfaces of the frame portion 104.
It is preferable that the molding surface of the mold 100 be coated with a mold release agent. In this case, in order to improve adherence force between the mold 100 and the mold release agent, it is preferable that the mold 100 (molding surface of the mold 100, that is, mold release surface) be cleaned before the mold release agent is applied to the mold 100. The cleaning can be performed by an ultrasonic cleaning, an acid cleaning, an UV ozone cleaning, and so on. Preferably, the molding surface to be coated with the mold release agent (i.e. a cleaned surface) is cleaned at the atomic level. One of examples of the mold release agent is a fluorine series mold release agent such as “OPTOOL DSX” available from DAIKIN INDUSTRIES, Ltd. The mold release agent may be a silicon series mold release agent or a wax release agent. The mold release agent is applied by dipping, spraying, brushing and so on, and thereafter, is formed in the form of a film on the surface (molding surface) of the mold 100 through a drying step and a washing step. The surface of the mold 100 may be coated by an inorganic film treatment with a DLC (Diamond Like Carbon) coating. Further, the surface of the mold 100 may be coated by a combination of the inorganic film treatment and the mold release agent treatment.
A porous plate 120 through which gases can pass is prepared (refer to
As shown in
In this slurry filling step, the slurry SL is filled into the mold 100 in an amount more than necessary (i.e., an excessive amount of slurry SL is filled). This is because, a pressure (filling pressure) of the slurry SL while filling the slurry SL is increased (enhanced) to thereby improve the filling rate of the slurry SL. This is also because it is necessary to take into consideration shrinkage of the slurry SL when it is being dried. As a result, as shown in
Meanwhile, as shown in
The casing 140 is placed on a hot plate (a heating apparatus) 150. The hot plate 150 generates heat when energized to heat a lower surface of the porous plate 120 (i.e., the other surface, or one portion of the porous plate 120) through the casing 140 and the sintered metal 130.
Subsequently, as shown in
Consequently, as shown by arrows in
Further, in this step, the aforementioned vacuum pump is driven. Driving the vacuum pump allows gases existing in the porous plate 120 to be discharged (refer to white frame arrow A). Therefore, a pressure in the porous plate 120 becomes lower than the atmospheric pressure (e.g., lower than the atmospheric pressure by 80 kPa). Thus, the solvent included in the slurry SL is sucked into the fine pores of the porous plate 120 (especially, the fine pores in the vicinity of the surface of the porous plate 120) (or, the solvent permeates into the fine pores and is evaporated) efficiently. In such a case, a degree of vacuum (the pressure in the porous plate 120) is preferably 0 to −100 kPa, and more preferably −80 to −100 kPa.
It should be noted that it is more preferable that the sintered metal 130 and the porous plate 120 be sealed up by covering “the exposed surface of the sintered metal 130 and the exposed surfaces of the porous plate 120” with a gas tight film or the like, when the pressure in the fine pores of the porous plate 120 is lowered by driving the vacuum pump. The exposed surface of the sintered metal 130 is a portion of the surfaces of the sintered metal 130 which is not covered by “the casing 140 and the porous plate 120”. The exposed surfaces of the porous plate 120 are portions composed of the side surfaces of the porous plate 120 and a portion of the flat surface (upper surface) 120u of the porous plate 120 which is not covered by the mold 100 (in actuality, the slurry SL). If “the exposed surface of the sintered metal 130 and the exposed surfaces of the porous plate 120” are not sealed up, the degree of vacuum in the porous plate 120 decreases, and therefore, an efficiency in evaporation of the solvent decreases. Further, a negative pressure is generated at portions from which the solvent of the slurry SL was evaporated, and therefore, air is introduced into the portions. As a result, air holes may be generated in the slurry SL, especially in the vicinity of the porous plate 120. In contrast, as described above, when “the exposed surface of the sintered metal 130 and the exposed surfaces of the porous plate 120” are sealed up, the generation of such air holes can be prevented.
Furthermore, in this step, the hot plate 150 is energized. Therefore, a temperature of the porous plate 120 increases, and thereby the solvent which has permeated into the fine pores of the porous plate 120 can be easily evaporated (or diffused). As a result, the slurry SL is dried and becomes solidified, so that a compact-after-dried 110 (compact 110 which has been dried) is formed between “the mold 100 and the porous plate 120”.
It should be noted that, in this step, the hot plate 150 may be placed at an uppermost position, the casing 140, the sintered metal 130, and the porous plate 120 may be held below the hot plate 150, and the “mold 100 into which the slurry SL is filled” may be pressed against the porous plate 120. That is, the arrangement shown in
Decreasing the pressure in the fine pores of the porous plate 120 by driving the vacuum pump is optionally performed. Thus, the sintered metal 130 and the casing 140 may be replaced with a simple base. Further, heating the porous plate 120 by the hot plate 150 is also optionally performed. Thus, the hot plate 150 may be omitted. Furthermore, the mold 100 is pressed against the porous plate 120 with the appropriate force when the mold 100 is placed so as to oppose to the porous plate 120, in the present example. However, during “decreasing the pressure in the fine pores of the porous plate 120 by driving the vacuum pump and heating the porous plate 120 by the hot plate 150” after that, no force may be applied to the mold 100, or an appropriate force may be applied to the mold 100 so that a density of the porous plate 120 does not change locally.
Thereafter, when the slurry SL has dried, and therefore, “the compact-after-dried 110” has been formed, “the mold 100, the porous plate 120, and the compact-after-dried 110” are cooled. Then, as shown in
In this demolding step, it is preferable that the vacuum pump be driven so as to decrease the pressure in the sintered metal 130. This allows the sintered metal 130 to hold the porous plate 120 stably, when the mold 100 is removed (during demolding). As a result, it is possible to prevent the porous plate 120 from being lifted up, and thus, a deformation of the porous plate 120 and a deformation of the compact-after-dried 110 (i.e., breakage of the pattern) can be avoided.
Subsequently, the compact 110 is separated from the porous plate 120. As a result, the compact 110 shown in
It should be noted that, before the demolding step is performed, the porous plate 120 may be released from the compact 110, and thereafter, a surface of the compact 110 from which the porous plate 120 was released may be fixed using a heat reactive adhesive film or suction, and so on. Thereafter, the demolding step may be performed under such a state to thereby release the mold 100 from the compact 110 to obtain the compact 110 shown in
The thus formed compact 110 has a remnant membrane (remained residual film) RF, as shown in a circle with a dashed line in
As described above, the compact forming step is a step for forming the compact-after-dried 110 by placing the porous plate 120 and the mold 100 in such a manner that they oppose (face) to each other while the slurry SL is maintained (or kept, held) between “the flat surface 120u of the porous plate 120 and the molding surface of the mold 100”, and drying the slurry SL through having the solvent included in the slurry SL permeate into the fine pores of the porous plate 120.
Subsequently, the remnant membrane RF is removed (eliminated) by a laser processing. That is, as shown in
In the meantime, a ceramic green sheet to be the vibration plate 30 and a ceramic green sheet to be the liquid storage chamber cover member 40 are prepared, separately. Further, a through hole to be the liquid supply through hole 40a is formed in the ceramic green sheet to be the liquid storage chamber cover member 40 at an appropriate position. Thereafter, the ceramic green sheet to be the vibration plate 30 and the ceramic green sheet to be the liquid storage chamber cover member 40 are layered (stacked) on the head body-before-fired 20A while aligning them in a planar direction. Subsequently, these are joined by a thermal compression bonding, and the thermal compression bonded layered body is fired after it is degreased. As a result, the head body 20 (fired layered body, a droplet discharge head body-after-fired) having the vibration plate 30 and the liquid storage chamber cover member 40 is completed.
Thereafter, according to a well-known method, piezoelectric elements are formed at predetermined positions. For example, the head body 20 and a piezoelectric element including a fired piezoelectric membrane are joined. At this time, the fired piezoelectric membrane is placed on the upper surface of the vibration plate 30. Subsequently, a mask is formed on the piezoelectric element, and fine particles (abrasive grains) are injected/projected to the mask to thereby remove (eliminate) the piezoelectric element on which the mask does not exist. That is, so-called “blast processing” is used to form the piezoelectric elements 50 (refer to, for example, Japanese Patent No. 3340043). By means of these processes, the droplet discharge head 10 is completed. It should be noted that piezoelectric elements which have not been fired may be formed on the vibration plate 30 at predetermined positions, and thereafter, the piezoelectric elements may be fired.
According to the manufacturing method described above, the “compact-after-dried 110” is made by drying the slurry SL using the single mold 100 in the single compact forming step. Therefore, it is unnecessary to form two compacts-after-dried using two molds, and to join the two compacts-after-dried. Thus, the processes can be simplified. In addition, it is unnecessary to join a “metal plate having through holes, each of which is to be communicated with each of the nozzle sections 21b (discharge hole tip portion forming member which is, for example, a nozzle plate made of SUS, or the like)” to the lower surface 20a of the droplet discharge head body 20. Thus, the processes can be further simplified. Moreover, it is unnecessary to join the two compacts-after-dried by a pressure bonding while aligning those two compacts, and therefore, the droplet discharge head having a desired shape can easily be manufactured.
It should be noted that as long as the slurry preparing step, the mold preparing step, and the porous plate preparing step are performed before the compact forming step, these steps can be performed in any order.
In place of “removing the remnant membrane RF (forming the through holes H) by the laser processing” in the head-body-before-fired forming step included in the manufacturing method described above, the remnant membrane RF may be removed by a precision polishing after the compact-after-dried 110 is fired. That is, the remnant membrane RF may be removed by a polishing processing after the compact 110 is fired. This enables to precisely adjust a diameter of each of the tip portion (portion of the opening, droplet discharge opening) of the nozzle sections 21b, and therefore, the nozzle plate (discharge hole tip portion forming member) which is another member (e.g., SUS, or the like) may not need to be used.
In place of “removing the remnant membrane RF (forming the through holes H) by the laser processing” in the head-body-before-fired forming step included in the manufacturing method described above, the remnant membrane RF may be removed (eliminated) by a polishing as shown in
More specifically, this polishing is performed as follows.
Firstly, when the compact-after-dried 110 has been formed in the mold 100 as shown in
Subsequently, as shown in
Polishing the compact-after-dried 110 in a state in which the compact-after-dried 110 is maintained in the mold 100 (i.e., performing a “polishing process-before-demolding”) in this manner has advantages as follows.
If polishing is performed on a compact-after-fired, grinding sludge and/or abrasive grains may enter into the pressure chambers, and so on. Accordingly, removing (eliminating) step for eliminating them is necessary. In contrast, according to the method described above, the compact-after-dried 110 is polished in the state in which the compact-after-dried 110 is maintained in the mold 100, and therefore, grinding sludge and/or abrasive grains do not enter into the pressure chambers, and so on. Therefore, such a removing (eliminating) step is not necessary. Consequently, the manufacturing method as a whole can be simplified.
Since the polishing is performed with using the back side of the mold 100 (i.e., surface opposite to the molding surface) as a reference, a flatness of the surface to be polished (exposed surface of the compact-after-dried 110) can be easily ensured.
Since the “compact-before-fired 310” has lower hardness compared to a fired body, a polishing rate can be increased. That is, the polishing can be completed within shorter time.
It should be noted that, when the “polishing process-before-demolding” is performed, a material having a high hardness is preferably used for the mold 100, or a DLC (diamond like carbon) treatment is preferably applied to the surfaces of the mold 100.
In place of “removing the remnant membrane RF (forming the through holes H) by the laser processing” in the head-body-before-fired forming step included in the manufacturing method described above, the remnant membrane RF may be removed (through holes H are formed) by a “special blast processing using elastic grains (described later)” after the compact-after-dried 110 is fired, to thereby complete the nozzle sections 21b.
More specifically, in the third modified example, “the ceramic green sheet to be the vibration plate 30 and the ceramic green sheet to be the liquid storage chamber cover member 40” are layered (stacked) on the compact-after-dried 110 from which the remnant membrane RF has not been removed yet, while aligning them in a planar direction. Subsequently, these are joined by a thermal compression bonding, and the thermal compression bonded layered body is fired after it is degreased. As a result, the head body-after-fired 20B (droplet discharge head body-before-fired) as shown in (A) of
Subsequently, as shown in (B) of
When projecting the polishing agents K having an elasticity, as shown in (C) of
According to the blast processing (special blast processing using elastic body), even when the head body-after-fired 20B has small undulation/warpage (deformation, twist) caused by being fired, the droplet discharge head body-after-fired can be polished by a constant amount according to the undulation/warpage. Therefore, a diameter (nozzle diameter) of the tip portion of the nozzle sections 21b (i.e., the opening for the droplet discharge formed on the surface by each of the nozzle sections 21b) can be maintained/controlled within a desired range.
In addition, according to the special blast processing using elastic body, a surface roughness of the surface 20a (refer to
Furthermore, according to the special blast processing using elastic body, since the diameter Dk of the polishing agent K (diameter of the base material) is large, it is unlikely that the polishing agents K enter into “hollow cavities of the nozzle sections 21b”. Accordingly, it is not necessary to include a step for removing them, or it is easy to remove them.
It should be noted that, as described above, it is preferable that the injection/projection direction of the polishing agent be different from 90° (that is, different from the normal line of the surface of the object to be processed, or the direction which is not perpendicular to a wall surface to be processed), in the special blast processing using elastic body. Further, the special blast processing using elastic body can be performed before the mold 100 is released from the compact 110 (i.e., before the demolding), and can also be performed after the mold 100 is released from the compact 110 (i.e., after the demolding).
As described above, according to the method for manufacturing a droplet discharge head in accordance with the embodiment and the modified examples of the present invention, the nozzle section is formed without punching using “a mold and a die”. Accordingly, the nozzle sections have no rough fracture surfaces, and it is unlikely that burrs and cracks are generated in the nozzle sections. As a result, the droplet discharge head capable of stably discharging droplets can be provided.
Further, according to the manufacturing method described above, the pressure chambers 21 are made by forming the slurry using the mold 100. Therefore, the droplet discharge head 10 having an excellent shape accuracy can be manufactured, even if the pressure chambers 21 are miniaturized, and/or a distance between the pressure chambers 21 adjacent to each other is short, and so on.
Further, according to the manufacturing method described above, the nozzle sections 21b are also made by forming the slurry using the mold 100. Therefore, the surface of each of the nozzle sections 21b is smooth, and is unlikely to have burrs or the like, as compared with the case in which the nozzle sections are formed by punching using a mold and a die. As a result, the droplet discharge head 10 capable of stably discharging droplets can be provided.
Furthermore, according to the manufacturing method described above, it is not necessary to join a “metal plate having through holes, or the like” to the nozzle sections 21b of the droplet discharge head body 20. Therefore, the manufacturing processes can be further simplified.
It should be noted that the present invention is not limited to the above embodiments, but various modifications may be adopted within the scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-128581 | Jun 2010 | JP | national |
