JP2008207336A - Droplet discharg head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a droplet discharge head which can eject a high-viscosity liquid at normal temperatures by a high drive frequency. <P>SOLUTION: A beam member 14 can deflect in a liquid droplet ejection direction and the opposite direction, ejecting the liquid 4 which is supplied from a pool 24 formed inside of a holding member 18 and is led to a nozzle 16 travelling on an anti-ejection surface of the beam member 14, as liquid droplets in the ejection direction by inertia. An orifice 24A is formed on the anti-ejection surface side of the pool 24, which communicates from within the pool 24 to a liquid reservoir 13. The liquid reservoir 13 is formed by both the un-ejection surface of the beam member 14/an actuator 36 and a plate-like member 12 prepared with a predetermined gap 13A spaced therefrom. The liquid 4 oozes from the orifice 24A to the gap 13A. The liquid 4 collected in the gap 13A travels oozing through the un-ejection surface of the beam member 14/actuator 36 subjected to lyophilic processing to the liquid 4 up to the nozzle 16. Thus the nozzle 16 is supplemented with the liquid 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a droplet discharge head, and more particularly to a droplet discharge head that discharges high-viscosity ink as droplets.

  A currently marketed aqueous inkjet printer known as a droplet discharge device employs a dye ink or a pigment ink having a viscosity of about 5 cps or so and an order of 10 cps at most. Reasons such as prevention of ink bleeding when landing on the medium, increase in optical color density, suppression of swelling / short time drying of the medium due to reduced water content, or greater freedom in total design of such high quality ink Therefore, it is known that the printing performance can be improved by increasing the ink viscosity.

  On the other hand, in order to discharge a high viscosity liquid, a high output pressure generating mechanism is required, which causes adverse effects such as cost and increase in head size. Conventionally, a technique for forcibly lowering the ink viscosity at the time of ejection by separately providing a heater in the ejector is known (see, for example, Patent Document 1). However, the above-described method of heating ink causes ink deterioration and flow path damage. There is a fundamental problem to be accelerated, and the ink that can be used is limited to one that does not deteriorate due to heat.

  In addition, there is disclosed a technique (for example, see Patent Document 2) in which ink flow in the reverse direction when ink is ejected is suppressed by a beam-like valve and ink with higher viscosity is ejected.

  As a method of powering up the pressure generation mechanism itself using a seat bending beam that can obtain a large deformation, a technique using a diaphragm actuator that deforms due to a difference in thermal expansion with the heating element layer (see, for example, Patent Document 3), Further, a technique using a cantilever-like actuator with the same configuration (for example, see Patent Document 4) is disclosed.

  However, even with the above-described conventional technology, it is extremely difficult to stably discharge a high-viscosity liquid having a viscosity of 50 to 100 cps, which greatly exceeds 10 cps, at room temperature.

  The inventors of the present application have applied a compressive and rotational motion to the beam, and a droplet discharge that causes a high-viscosity droplet to inertially release from the nozzle in a desired direction using the steep vertical motion when the seat bending direction is reversed. The head was filed earlier (see Patent Documents 5 to 8).

  That is, as in the ink discharge head 100 shown in FIGS. 8A and 8B, the ink replenished from the ink pool 124 passes through the ink flow path 113 in the ink flow path member 112 provided integrally with the beam member 114. When the beam member 114 passes through and reaches the nozzle 116 and is buckled and reversed in the ejection direction, high-viscosity ink is ejected from the nozzle 116.

  As a result of the inventor's investigation on the above problems, in order to discharge a highly viscous liquid in the above-described head, the delay in refill (liquid supply to the nozzle) caused by the flow resistance of the highly viscous liquid is solved. Unlike the conventional method of refilling by sending liquid to the nozzle through a closed channel, the inner wall of the nozzle and the back of the beam are formed with high liquid wettability, and pressure is applied to the liquid. It has been found that a method of providing an open flow path that does not apply and supplying a liquid to the nozzle by utilizing the phenomenon that the liquid spreads through the flow path portion is effective.

  In addition, a liquid reservoir (reservoir with the free surface of the liquid exposed) is provided on the opposite side of the nozzle immediately below the nozzle, and when the beam is elastically deformed to the opposite side of the ejection direction, the nozzle back surface and the liquid surface of the liquid reservoir are It has been found that the method of filling the nozzle holes with liquid by contacting them is also effective.

The present invention is an advanced technology of the prior application, and an object of the present invention is to provide a head that can improve the refill delay of a high-viscosity liquid and can eject droplets at higher speeds / high frequencies.
JP 2003-220702 A Japanese Patent Laid-Open No. 9-327918 JP 2003-118114 A JP 2003-34710 A Japanese Patent Application No. 2004-322341 Japanese Patent Application No. 2004-322342 Japanese Patent Application No. 2004-322343 Japanese Patent Application No. 2004-322344

  In consideration of the above facts, an object of the present invention is to provide a droplet discharge head capable of discharging a high-viscosity liquid at a high drive frequency at room temperature.

  The droplet discharge head according to claim 1, wherein a beam member that is buckled and inverted so as to be convex on the droplet discharge surface after being buckled and inverted so as to be concave on the droplet discharge surface, and the liquid A nozzle penetrating from the droplet ejection surface to the anti-droplet ejection surface having higher wettability with respect to the liquid ejected from the droplet ejection surface, and provided at at least one end in the longitudinal direction of the beam member through the anti-droplet ejection surface And a liquid reservoir for supplying the liquid to the nozzle.

  In the invention of the above configuration, since the liquid transmitted from the liquid reservoir to the side opposite to the discharge surface of the beam member is discharged from the nozzle, there is no need to provide the beam member with a flow path member for pressurizing and feeding the liquid to the nozzle. Therefore, a delay in liquid supply to the nozzle and a delay in meniscus return can be prevented.

  The liquid droplet ejection head according to claim 2, wherein the liquid pool is a gap formed between the beam member and a plate-like member provided with a predetermined gap from the beam member. And

  In the invention with the above configuration, since the liquid pool is formed between the beam member and the plate-like member, the liquid can be fed to the nozzle with a simple structure.

  The droplet discharge head according to claim 3 is characterized in that the discharge surface of the beam member is subjected to a liquid repellent treatment for improving liquid repellency with respect to the liquid.

  In the invention having the above-described configuration, the liquid hardly spreads on the discharge surface of the beam member, and when the beam member is buckled and reversed in the discharge direction, the liquid droplet is easily detached from the discharge surface.

  The droplet discharge head according to claim 4 is characterized in that a lyophilic treatment for increasing the lyophilicity of the liquid is performed on the opposite discharge surface of the beam member.

  In the invention having the above-described configuration, the liquid transmitted on the anti-discharge surface of the beam member is likely to spread, and when the beam member is buckled and reversed in the discharge direction, the liquid is likely to collect at the nozzle.

  The droplet discharge head according to claim 5 is characterized in that the lyophilic process is a process of forming fine irregularities on the opposite discharge surface of the beam member.

  In the invention with the above configuration, the lyophilicity of the anti-ejection surface of the beam member can be enhanced by a simple method such as fine blasting.

  The droplet discharge head according to claim 6 is a beam member that is buckled and inverted so as to be convex on the droplet discharge surface after being buckled and inverted so as to be concave on the droplet discharge surface, and the liquid A nozzle penetrating from the droplet ejection surface to the anti-droplet ejection surface having higher wettability for the liquid ejected from the droplet ejection surface, and the beam member on the side opposite to the ejection surface, the beam member being in the droplet ejection direction And a liquid reservoir with which the portion near the nozzle on the side opposite to the ejection surface of the beam member comes into contact when buckling and reversing deformation so as to be concave.

  In the invention of the above configuration, since the liquid that has been transferred from the liquid reservoir to the vicinity of the nozzle on the side opposite to the discharge side of the beam member and transmitted to the inner wall of the nozzle is discharged from the nozzle, the flow path member that supplies the liquid to the nozzle under pressure is provided. Since there is no need to provide the beam member and no fluid resistance is generated, a delay in liquid supply to the nozzle and a delay in meniscus return can be prevented.

  The liquid droplet ejection head according to claim 7 is characterized in that the liquid reservoir contacts only in the vicinity of the nozzle of the beam member.

  In the invention with the above configuration, since the liquid reservoir in contact with the beam member is in contact only in the vicinity of the nozzle, the liquid shear resistance generated at the time of buckling reversal can be suppressed by contact of the portion other than the nozzle with the liquid reservoir.

  The liquid droplet ejection head according to claim 8 is characterized in that a treatment for increasing the lyophilicity of the liquid is performed in the vicinity of the nozzle on the inner wall surface of the nozzle and the opposite ejection surface of the beam member.

  In the invention with the above configuration, the liquid easily moves from the liquid reservoir to the opposite discharge surface of the beam member subjected to the lyophilic treatment, and when the beam member buckles and reverses in the discharge direction, the liquid easily collects in the nozzle.

  The droplet discharge head according to claim 9, wherein a treatment for increasing liquid repellency with respect to the liquid is performed on the anti-discharge surface of the beam member excluding the vicinity of the nozzle and the discharge surface of the beam member. And

  In the invention having the above-described configuration, the liquid is unlikely to spread on the ejection surface of the beam member and the portion other than the nozzle on the counter-ejection surface, and when the beam member is buckled and reversed in the ejection direction, the liquid droplets are easily detached from the ejection surface.

  The liquid droplet ejection head according to claim 10, wherein the liquid reservoir protrudes from between the plate-like members by pumping the liquid between two plate-like members provided with a predetermined gap. It is characterized by the liquid level rising in a shape.

  In the invention having the above-described configuration, the liquid can be supplied to the nozzle without requiring a closed flow path or chamber for pumping the liquid. Further, since the beam member and the plate member of the liquid reservoir can be made non-contact, it is possible to provide a liquid droplet ejection head that is excellent in silence and durability.

  The liquid droplet ejection head according to claim 11 is characterized in that the liquid reservoir is the liquid soaked in a porous elastic body.

  In the invention having the above-described configuration, it is not necessary to pressurize and supply the liquid, so that a simpler structure can be obtained.

  Since the present invention has the above-described configuration, a droplet discharge head capable of discharging droplets having a high viscosity at room temperature at a high driving frequency can be obtained.

<Basic configuration>
FIG. 1 shows a droplet discharge head according to a first embodiment of the present invention.

  As shown in FIGS. 1A to 1C, the droplet discharge head 10 is supported by the holding member 18 at both ends in the length direction of the beam member 14 having the nozzle 16 at substantially the center in the length direction. Is fixed to the rotary encoder 20 and is pressed from both ends in the length direction as the rotary encoder 20 is rotated, or a force is applied in the bending direction, and the beam member 14 in the droplet discharge direction (upper in the figure) or in the opposite direction. The structure is bent.

  As shown in FIG. 1B, a thin film piezo element 30 is joined to the beam member 14, and an individual electrode 32 is formed on the piezo element 30, and the beam member 14, the piezo element 30, and the individual electrode 32 are used. An actuator 36 is configured. The beam member 14 also serves as a common electrode of the piezo element 30, and has a structure in which the piezo element 30 is sandwiched between the beam member 14 and the individual electrode 32.

  An electrode pad 33 is provided at one end of the individual electrode 32 and connected to a switching IC (not shown) by wiring. The piezo element 30 is driven by a signal from the switching IC, and the beam member 14 is controlled to be bent / not bent.

  The nozzle 16 is formed through the actuator 36 including the beam member 14 in the discharge direction (up and down in the drawing), and the discharge surface (upper side in the drawing) of the beam member 14 is subjected to a liquid repellent treatment with respect to the liquid 4. A lyophilic process is performed on the liquid 4 on the opposite discharge surface (lower side in the figure) of the beam member 14 / actuator 36. In addition, an insulating protective film is formed over the entire surface to protect the piezo element 30 from corrosion caused by liquid, short-circuit between electrodes, and the like.

  In this embodiment, each beam member 14 is made of a SUS material having a thickness of 10 μm, a width of 150 μm, and a length of 5 mm, and a plurality of beam members 14 are arranged at a pitch of 170 μm as shown in FIG. It has a configuration. Further, the nozzle 16 formed by laser processing on the beam member 14 has a diameter of 30 μm, and the hole diameter is increased to 60 μm in a portion penetrating the actuator 36 so that the liquid 4 is easily filled.

  The beam member 14 can be bent in the droplet discharge direction (upper side in the figure) and in the opposite direction, and is supplied from a pool 24 provided inside the holding member 18, and travels along the anti-discharge surface (lower side in the figure) of the beam member 14. Then, the liquid 4 reaching the nozzle 16 is discharged as droplets in the discharge direction by inertia.

  An opening 24 </ b> A is provided on the counter discharge surface side of the pool 24, and communicates from the inside of the pool 24 to the liquid reservoir 13. The liquid reservoir 13 is formed of the beam member 14 / actuator 36 on the opposite discharge surface (lower side in the figure) and the plate-like member 12 provided with a predetermined gap 13A (about 100 μm), and the liquid 4 passes through the opening 24A. The liquid 4 that has oozed into the gap 13A and accumulated in the gap 13A spreads to the nozzle 16 on the anti-ejection surface (lower side in the figure) of the beam member 14 / actuator 36 on which the lyophilic treatment has been applied to the liquid 4. In the present embodiment, the lyophilic treatment is performed by a method of forming fine irregularities on the surface by blasting in which fine abrasive grains of mesh 4000 are sprayed on the side opposite to the discharge surface.

  As described above, the discharge liquid used here prevents bleeding when landing on the medium, increases the optical color density, suppresses swelling of the medium by reducing the water content, or dries for a short time, or totalizes such high-quality ink. For example, it is a high viscosity liquid having a very high liquid viscosity, for example, a viscosity much higher than 20 cps, for example, 50 to 100 cps, because the degree of freedom in designing can be increased.

  In the present embodiment, even if the viscosity of the liquid 4 is large as described above, it is not a closed flow path in which a large fluid resistance is generated, but is open to the liquid 4 as a flow path that is open and has low flow resistance and no pressure is applied. Refilling (refilling) the liquid 4 ejected as droplets 2 from the nozzle 16 by the liquid 4 spreading to the nozzle 16 on the opposite ejection surface (lower side in the figure) of the beam member 14 / actuator 36 subjected to the liquid treatment. ), The return of the meniscus (liquid level) is eliminated, and a liquid droplet discharge head that stably discharges liquid droplets at high speed and high frequency while using the high viscosity liquid 4 can be obtained.

  Furthermore, in the present embodiment, in addition to the fact that the increase in flow path resistance due to the reduction in the diameter of the liquid flow path due to the higher density of the nozzles 16 (minimization of the pitch) associated with higher image quality does not occur, the conventional flow path Stable high-viscosity liquid without fear of joining the beam and beam members, filling the flow path member with liquid, increasing the weight of the beam member or flow path member, and deteriorating discharge performance due to reduced buckling reversal speed Thus, it can be discharged at high density and high speed.

<Discharge principle>
2 and 3 show the operation of the droplet discharge head according to the first embodiment of the present invention.

  First, when the actuator 36 is not driven and the droplet 2 is not discharged, for example, the beam member 14 is bent in the droplet discharge direction (upper side in the drawing) as shown in FIG. In addition, the actuator 36 is not driven because a signal instructing ejection is not sent from the switching IC.

  When the rotary encoder 20 is rotated in the direction of the arrow as shown in FIG. 2 (A-2), first, bending occurs in the discharge direction (upper in the figure), and the beam is directly used as shown in FIG. 2 (A-3 to 4). The member 14 only bends in the droplet discharge direction, and the beam member 14 always remains convex in the droplet discharge direction until the deflection amount reaches the maximum in FIG. 2A-4.

  That is, the liquid 4 inside the beam member 14 is not sufficiently accelerated in the discharge direction (upper side in the figure) until the beam member 14 is displaced as shown in FIGS. There is no discharge from the nozzle 16 (FIG. 2 (A-5)).

  Further, after the deflection amount becomes maximum in FIG. 2 (A-4) and the rotary encoder 20 stops, the beam member 14 returns to the initial position FIG. 2 (A-1) by rotating backward to flatten the beam member 14. To do.

  On the other hand, when the actuator 36 is driven and the droplet 2 is ejected, a signal instructing ejection is sent from the switching IC, and the actuator 36 is driven as shown in FIG. Is a state in which the concave portion (lower in the figure) is bent with respect to the droplet 2 ejection direction, and the rotary encoder 20 is rotated forward (arrow in the figure) as shown in FIG. 2 (B-2 to 4). Direction), the bending direction of the beam member 14 gradually changes from the both ends closer to the rotary encoder 20, that is, from both ends to the convex in the discharge direction (upper in the drawing).

  When this change in deflection direction approaches the center from both ends, the beam member 14 undergoes a steep buckling reversal at a certain point, and deforms rapidly in the droplet 2 ejection direction (upper in the figure) (FIG. 2 (B-3)). To 4) with emphasis on deformation at the center.

  Since the nozzle 16 is provided substantially at the center in the length direction of the beam member 14, the liquid 4 reaching the nozzle 16 moves from the nozzle 16 to the liquid in accordance with the deformation in the discharge direction of the beam member 14 due to the buckling inversion. It is discharged as a droplet 2 (enlarged view 2 (B-5)).

  Further, in FIG. 2 (B-4), after the amount of bending becomes maximum and the rotary encoder 20 stops, the beam member 14 returns to the initial position by rotating backward to flatten the beam member 14, and the droplet discharge direction ( Return to the state with deflection in the upper part of the figure.

  In the above-described embodiment, when the actuator 36 is driven, the beam member 14 is bent concavely (lower in the drawing) in the discharge direction, and buckling reversal occurs to discharge the droplet 2. The beam member 14 is previously bent in a concave shape with respect to the discharge direction when the drive 36 is not driven, and the beam member 14 is bent in a convex shape (upward in the drawing) with respect to the discharge direction when the actuator 36 is driven. Similarly, ejection / non-ejection of the droplet 2 can be controlled by the presence or absence of a signal.

  The deformation due to the buckling reversal is much larger than the displacement due to a normal actuator or the like, and even the high viscosity ink employed in the present invention can be sufficiently discharged as the ink droplet 2. .

  FIG. 3 shows the movement during the discharge operation of the liquid 4 in the vicinity of the nozzle 16.

  In the liquid 4 of the liquid reservoir 13 shown in FIG. 3A, the beam member 14 is recessed (or formed in advance) in the discharge direction by the actuator 36 in the vicinity of the nozzle 16 as shown in FIG. As shown in an enlarged view in FIG. 3C, the liquid 4 filled in the gap between the plate-like member 12 and the beam member 14 from the pool 24 (not shown) through the opening 24A (not shown) It reaches the vicinity of the nozzle 16 while spreading through the anti-ejection surface of the beam member 14 that has been subjected to the liquid treatment.

  At this time, due to the buckling inversion of the beam member 14 by the actuator 36, the movement of the liquid 4 is accelerated by applying a centrifugal force to the liquid 4 in the direction of the nozzle 16. Further, the liquid 4 is filled in the nozzle 16 as shown in FIG. 3 (B-3), and the beam member 14 is buckled and reversed by the operation of the rotary encoder 20, so that the nozzle 16 as shown in FIG. 3 (B-4 to 5). A large acceleration is applied to the inner liquid 4 in the discharge direction (upper in the figure), and the liquid 4 is discharged as a droplet 2.

Second Embodiment
FIG. 4 shows a droplet discharge head according to a second embodiment of the present invention.

  As shown in FIG. 4A, the droplet discharge head 11 is supported by the holding member 18 at both ends in the length direction of the beam member 14 provided with the nozzle 16 at substantially the center in the length direction, and the holding member 18 is a rotary encoder 20. A structure in which the beam member 14 is bent in the droplet discharge direction (upper direction in the figure) or in the opposite direction by being pressed from both ends in the length direction as the rotary encoder 20 is rotated, or by applying a force in the bending direction. This is the same as in the first embodiment.

  In the present embodiment, the liquid reservoir 13 is not provided on the holding member 18 but is provided on the non-ejection side (lower in the drawing) of the beam member 14, and the liquid member 13 is moved by the movement of the beam member 14 near the nozzle 16 by the rotary encoder 20 or the actuator 36. When the surface and the beam member 14 are in direct contact with each other, the liquid 4 is supplied / supplemented to the opposite discharge surface of the beam member 14 subjected to the lyophilic treatment.

  As shown in FIG. 4 (B), the liquid reservoir 13 is provided with a plurality of plate-like members 12 at a predetermined interval, and pressurizes and supplies the liquid 4 in which the hydraulic pressure 4A is applied to the gap 13A of the plate-like member 12. ing. Since the liquid 4 is pressurized, a liquid surface 4B that rises from the gap 13A due to surface tension is formed, and only the liquid 4 comes into contact with the opposite ejection surface of the beam member 14. Thereby, generation | occurrence | production of the failure by interference noise generation | occurrence | production and impact with the beam member 14 and the plate-shaped member 12 can be prevented.

  At this time, a porous elastic body (for example, a sponge) may be provided so as to close the gap 13A. Thereby, scattering of the liquid 4 can be prevented at the time of contact between the beam member and the liquid reservoir 13. Further, the height of the liquid surface 4B can be controlled by the shape of the elastic body.

  FIG. 5 shows the operation of the droplet discharge head according to the second embodiment of the present invention.

  FIG. 5A-1 shows a state where the actuator 36 is driven to cause the beam member 14 to bend in the concave (lower in the drawing) with respect to the droplet 2 ejection direction. Since the liquid surface 4B in which the liquid 4 is raised from the liquid reservoir 13 by the hydraulic pressure 4A is formed from the liquid reservoir 13 as shown in FIG. 5B-1), the beam member 14 in the vicinity of the nozzle 16 is shown in FIG. The liquid 4 can be easily taken into the nozzle 16 by contacting the liquid surface 4B as shown in FIG.

  When the rotary encoder 20 is activated and the beam member 14 starts to move in the discharge direction as shown in FIG. 5A-2, the nozzle 16 moves away from the liquid surface 4B as shown in FIG. If the operation continues and the beam member 14 undergoes buckling reversal as shown in FIG. 5A-3, the liquid 4 in the nozzle 16 is ejected as a droplet 2.

  At this time, for example, when the liquid reservoir 13 exists not only in the vicinity of the nozzle 16 but also over the entire length direction of the beam member 14, the beam member 14 is liquid over substantially the entire length direction as shown in FIG. 4 in contact. When the beam member 14 and the liquid 4 are in contact with each other over a wide range as described above, an excessive liquid shear resistance is generated in the beam member 14 during the buckling reversal operation. As a result, the beam member 14 is pulled to the side opposite to the ejection side, and the steep inertia required at the time of ejection cannot be obtained, which may adversely affect the ejection performance.

  In order to prevent such a situation, it is preferable that the beam member 14 is in contact with the liquid surface 4B in the range of not less than the diameter of the nozzle 16 and 10 times the diameter. In this embodiment, the liquid reservoir 13 is provided with two plate-like members 12 with a gap of 250 μm, and the nozzle 16 is subjected to a lyophilic treatment within a range of 200 μm in diameter with respect to a hole diameter of 30 μm. The liquid surface 4B is configured to come into contact only in the nearest 16th.

<Third Embodiment>
FIG. 6 shows a droplet discharge head according to a third embodiment of the present invention.

  In the liquid droplet ejection head 21 according to this embodiment, holding members support both ends in the length direction of a beam member 14 provided with a nozzle 16 at substantially the center in the length direction, and the holding members are fixed to the rotary encoder. It is the same as the first embodiment in that the beam member 14 is deflected in the droplet discharge direction or in the opposite direction by being pressed from both ends in the length direction along with the movement or by applying a force in the bending direction. .

  In the present embodiment, the shape of the adjacent beam members 14 and the gap 15 are configured as shown in FIG. 6A, and the interval between the nozzles 16 is reduced by arranging the nozzles in a zigzag arrangement (the nozzle pitch is reduced). In addition, higher density discharge can be performed by increasing the nozzle density. For example, in the present embodiment, the width of the thin portion of the beam member 14 is 50 μm, the width of the beam member 14 in the portion where the open channel 14C is formed is 150 μm as in the first embodiment, and the gap 15 is 20 μm. Yes. Accordingly, the pitch of the nozzles 16 in the first embodiment is 170 μm, whereas in the present embodiment, the nozzles 16 can be aligned at a pitch of 120 μm.

  Further, the beam member 14 is not provided with a smooth surface structure, but is provided with an open flow path 14C subjected to a lyophilic process, and the liquid 4 is supplied to the nozzle 16.

  In this embodiment, the liquid 4 supplied from the liquid reservoir 13 (not shown) to the open flow path 14C is supplied / refilled to the nozzle 16 only by the wettability by the lyophilic process and the centrifugal force generated when the beam member 14 is buckled. Is done.

  6B and 6C are cross-sectional views of the open channel 14C as viewed from the left-right direction of the drawing. As shown in FIG. 6B, the open channel 14C is a slit extending from the liquid reservoir 13 to the nozzle 16, and the surface other than the open channel 14C is covered with the liquid repellent film 14A, and the inside of the slit is covered with the lyophilic film 14B. Thus, the liquid 4 is passed only through the open flow path 14C, and the liquid 4 is supplied from the liquid reservoir 13 to the nozzle 16 by the wettability due to the lyophilic treatment and the centrifugal force generated when the beam member 14 is buckled and reversed as described above. be able to.

  Alternatively, as shown in FIG. 6C, the open flow path 14C may be a groove provided on the non-ejection surface (left side in the figure) of the beam member 14 instead of the slit. In this case, the same effect can be obtained by covering the inside of the groove with the lyophilic film 14B and covering the other surface of the beam member 14 with the liquid repellent film 14A.

<Fourth embodiment>
FIG. 7 shows a droplet discharge head according to a fourth embodiment of the present invention.

  As shown in FIG. 7A, the droplet discharge head 31 is the first embodiment in that the holding member 18 supports both ends in the length direction of the beam member 14 provided with the nozzle 16 at the substantially center in the length direction. However, a rotation encoder for rotating the holding member 18 is not provided, and the presence or absence of ejection is controlled only by deformation of the piezoelectric actuator.

  As shown in FIG. 7A, the beam member 14 held in the longitudinal direction by the holding member 18 constitutes an actuator 36 that controls ejection / non-ejection together with the piezo element 30 and the individual electrode 32, and the common electrode A common wire 33 is provided on the opposite side surface of the piezo element 30 in the beam member 14 that also serves as the same. The individual electrode 32 and the common electric wire 33 are connected to an individual electrode pad and a common electrode pad (not shown), respectively, and the actuator 36 is driven by a signal from a switching IC (not shown) to control whether the beam member 14 is bent or not. Is called.

  First, as shown in FIG. 7 (B-1), the beam member 14 is deformed in the anti-discharge direction (in the drawing) by an actuator 36 that is bent in the anti-discharge direction (lower in the drawing) or is previously convex in the anti-discharge direction. (Below in the figure) (or the beam member 14 may also have a shape that is convex in the anti-discharge direction in advance).

  Here, the non-ejection surface of the beam member 14 comes into contact with the liquid surface 4 </ b> B of the liquid reservoir 13 and replenishes the nozzle 16 with the liquid 4. The liquid 4 is pressurized at a liquid pressure 4A (white arrow in the figure), and the liquid 4 can be easily taken into the nozzle 16 from the liquid surface 4B that rises in the discharge direction.

  Next, when the actuator 36 is activated and deformation is started in the discharge direction (upper in the figure), the beam member 14 bends, that is, the amount of deformation in the anti-discharge direction increases, but the support portion of the beam member 14 itself is in the discharge direction. Therefore, the beam member 14 in the vicinity of the nozzle 16 also moves in the discharge direction, and remains away from the liquid surface 4B while the nozzle 4 is filled with the liquid 4.

  Further, when the actuator 36 is deformed (increases in deflection) in the discharge direction in FIG. 7B-3, the beam member 14 undergoes buckling reversal deformation, and as shown in FIG. A droplet 2 is discharged in the discharge direction.

  At this time, as in the second embodiment, when the beam member 14 and the liquid 4 are in contact with each other over a wide range, an excessive liquid shear resistance is generated in the beam member 14 during the buckling reversal operation, and the steep inertia required at the time of discharge is generated. The liquid reservoir 13 is provided with the liquid surface 4B only in the vicinity of the nozzle 16 in order to prevent a situation in which the discharge performance is not adversely affected. In order to avoid deterioration of the discharge performance due to unnecessary adhesion of the liquid 4, and the liquid 4 is contacted and replenished to the nozzle 16 by the surface tension of the liquid 4, the vicinity of the nozzle 16 on the discharge surface side of the nozzle 16 or the beam member 14 opposite to the discharge surface side. The areas other than are liquid-repellent.

<Others>
In addition, this invention is not limited to said embodiment.

  For example, in the above-described embodiment, the actuator includes the piezo element 30 and the beam member 14, but an actuator that uses a heating resistor instead of the piezo element 30 and bends and deforms due to a difference in thermal expansion may be used. However, it may be one using electrostatic force or magnetic force. Or the actuator of another form may be sufficient.

  Further, the droplet discharge head in this specification is not necessarily limited to recording characters and images on recording paper using ink or the like. That is, the recording medium is not limited to paper, and the ejected liquid is not limited to ink. For example, industrial uses such as creating color filters for displays by discharging ink onto polymer films or glass, or forming bumps for component mounting by discharging liquid solder onto a substrate The present invention can be applied to all types of liquid droplet ejecting apparatuses.

It is a figure which shows the droplet discharge head which concerns on 1st Embodiment of this invention. It is a figure which shows the discharge operation of the liquid which concerns on this invention. It is a figure which shows operation | movement of the droplet discharge head which concerns on 1st Embodiment of this invention. It is a figure which shows the droplet discharge head which concerns on 2nd Embodiment of this invention. It is a figure which shows operation | movement of the droplet discharge head which concerns on 2nd Embodiment of this invention. It is a figure which shows the droplet discharge head which concerns on 3rd Embodiment of this invention. It is a figure which shows the droplet discharge head which concerns on 4th Embodiment of this invention, and its operation | movement. It is a figure which shows the conventional droplet discharge head.

Explanation of symbols

2 droplet 4 liquid 10 droplet ejection head 11 droplet ejection head 12 plate-like member 13 liquid pool 14 beam member 15 gap 16 nozzle 18 holding member 20 rotary encoder 21 droplet ejection head 24 pool 30 piezo element 31 droplet ejection head 32 Individual electrode 36 Actuator

Claims (11)

A beam member that is buckled and inverted so as to be concave on the droplet discharge surface, and then buckled and inverted so as to be convex on the droplet discharge surface;
A nozzle penetrating from the droplet discharge surface to the anti-droplet discharge surface having high wettability with respect to the liquid discharged from the droplet discharge surface;
A liquid reservoir that is provided at least at one end in the longitudinal direction of the beam member and supplies the liquid to the nozzle through the anti-droplet ejection surface;
A liquid droplet ejection head comprising:   2. The droplet discharge head according to claim 1, wherein the liquid pool is a gap formed between the beam member and a plate-like member provided with a predetermined gap from the beam member. .   3. The liquid droplet ejection head according to claim 1, wherein a liquid repellent treatment for improving liquid repellency is performed on the ejection surface of the beam member. 4.   4. The liquid droplet ejection head according to claim 1, wherein a lyophilic process is performed on the opposite ejection surface of the beam member to enhance the lyophilicity with respect to the liquid.   5. The liquid droplet ejection head according to claim 4, wherein the lyophilic process is a process of forming fine irregularities on the opposite ejection surface of the beam member. A beam member that is buckled and inverted so as to be concave on the droplet discharge surface, and then buckled and inverted so as to be convex on the droplet discharge surface;
A nozzle penetrating from the droplet discharge surface to the anti-droplet discharge surface having high wettability with respect to the liquid discharged from the droplet discharge surface;
A liquid reservoir provided on the side opposite to the ejection surface of the beam member, and when the beam member is buckled and inverted so as to be concave in the liquid droplet ejection direction, a liquid reservoir in contact with a portion near the nozzle on the side opposite to the ejection side of the beam member; A liquid droplet ejection head comprising:   The liquid droplet ejection head according to claim 6, wherein the liquid pool is in contact with only the vicinity of the nozzle of the beam member.   8. The lyophilic treatment for improving the lyophilicity of the liquid is performed in the vicinity of the nozzle on the inner wall surface of the nozzle and the anti-ejection surface of the beam member. The droplet discharge head described.   The liquid repellent treatment for improving liquid repellency with respect to the liquid is performed on the anti-discharge surface of the beam member excluding the vicinity of the nozzle and the discharge surface of the beam member. 2. A droplet discharge head according to item 1.   The liquid reservoir is a liquid surface that protrudes in a convex shape from between the plate-like members by pumping the liquid between two plate-like members provided with a predetermined gap therebetween. The droplet discharge head according to any one of claims 6 to 9.   The droplet discharge head according to claim 6, wherein the liquid pool is the liquid soaked in a porous elastic body.

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