JP2006130781A - Inkjet recording head and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording head which can eject a high-viscosity ink at normal temperatures and has a high ejection precision, and to provide an inkjet recorder. <P>SOLUTION: The inkjet recording head is equipped with an ink channel member 12 to which ink is supplied, a nozzle 16 formed at the center of the ink channel member 12, a beam member joined to the ink channel member 12, a first driving means which deflects the beam member, and a second driving member which bends ends of the beam member and deforms buckling the beam member in an ink droplet ejection direction. The second driving means deforms buckling the beam member in the ink droplet ejection direction and applies an inertia in the ejection direction to the ink near the nozzle, whereby ink droplets are ejected from the nozzle. The presence or absence of the buckling deformation by the second driving means is controlled by the deflection of the beam member by the first driving means. A beam-like ejector consisting of the ink channel member, the beam member and the first driving means has a rigidity near the center in a longitudinal direction made lower than that near both ends in the longitudinal direction in the inkjet recording head. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording head and an ink jet recording apparatus.

    Water-based inkjet printers currently on the market generally employ dye inks and pigment inks having a viscosity of about 5 cps 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 eject high-viscosity ink, a high-output pressure generation mechanism is required, which causes adverse effects such as an increase in cost and 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 by 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.

  For example, the ink jet recording head 100 shown in FIG. 17 rapidly pressurizes the ink 101 in the ink chamber 106 by deforming the actuator 102 as shown in FIG. 17A to FIG. It is made to discharge as.

  However, even with the above-described prior art, it is extremely difficult to stably eject a high viscosity ink having a viscosity of 50 to 100 cps, which greatly exceeds 10 cps, at room temperature.

An object of the present invention is to solve these problems, and in particular, to provide an ink jet recording head capable of discharging a high viscosity ink of the order of 50 to 100 cps at room temperature. Specifically, it is an ink jet recording head that applies compression and rotational motion to a beam, utilizes a steep vertical motion when the seat bending direction is reversed, and causes inertial separation of ink droplets from a nozzle in a desired direction. Provided is an ink jet recording head capable of increasing the accuracy of ink discharge direction and ink discharge timing of each nozzle.
JP 2003-220702 A (FIG. 1, pages 4 to 6) Japanese Patent Laid-Open No. 9-327918 (FIG. 1, pages 8 to 9) JP 2003-118114 A (FIG. 3, pages 4 to 5) JP 2003-34710 A (FIG. 13, pages 6 to 8)

  In consideration of the above facts, an object of the present invention is to provide an ink jet recording head and an ink jet recording apparatus with high ejection accuracy capable of ejecting high viscosity ink at room temperature.

  The ink jet recording head according to claim 1 is joined to the ink flow path member, an ink flow path member to which ink is supplied, a nozzle formed at a substantially center of the ink flow path member, and ejecting ink droplets. A beam member, a first driving means provided to be joined to the beam member, and bending the beam member; and bending the end of the beam member so that the beam member is convex from the concave in the ink droplet ejection direction. And a second driving unit that deforms the beam member such that the beam member is deformed from a concave to a convex in the ink droplet ejection direction, and gives an inertia in the ejection direction to the ink near the nozzle. An ink jet recording head that ejects ink droplets from nozzles, wherein the first driving means deflects the beam member to control the presence or absence of buckling reversal deformation of the beam member by the second driving means; in front Beam-shaped ejectors each composed of an ink flow path member and the beam member and the first drive means, characterized in that the stiffness of the substantially longitudinal central portion lower than the near both longitudinal ends.

  In the invention with the above configuration, since the rigidity in the vicinity of the center in the longitudinal direction of the beam member is lowered, the asymmetric bending method that deforms at a location other than the center of the nozzle when the buckling reversal deformation is caused by the second driving means. In this case, the ink droplet ejection direction can be regulated by correctly bending at the center.

  An ink jet recording head according to a second aspect of the invention is characterized in that a width at a substantially central portion in the length direction of the beam member is narrowed.

  In the invention with the above-described configuration, the width near the center of the beam member is narrowed to reduce the rigidity, the asymmetric bending is prevented, and the ink droplet ejection direction can be regulated by correctly bending at the center.

  The ink jet recording head according to claim 3 is characterized in that the width of the ink flow path member at the center in the length direction is narrowed.

  In the invention of the above configuration, the width near the center of the ink flow path member is reduced, the rigidity is reduced, the asymmetric bending is prevented, and the ink droplet ejection direction can be regulated by correctly bending at the center.

  The ink jet recording head according to claim 4, wherein one or both of the ink flow path member, the first driving unit, and the beam member have a thickness in the vicinity of the center in the longitudinal direction. It is characterized by being thinner than the vicinity of both ends in the longitudinal direction.

  In the invention with the above configuration, the ink droplet ejection direction can be regulated by lowering the rigidity in the vicinity of the center of one or both of the beam member and the ink flow path member, preventing asymmetric bending, and bending at the center correctly. .

  The ink jet recording head according to claim 5 is joined to the ink flow path member, an ink flow path member to which ink is supplied, a nozzle formed at substantially the center of the ink flow path member and ejecting ink droplets, and the ink flow path member. A beam member, a first driving means provided to be joined to the beam member, and bending the beam member; and bending the end of the beam member so that the beam member is convex from the concave in the ink droplet ejection direction. And a second driving unit that deforms the beam member such that the beam member is deformed from a concave to a convex in the ink droplet ejection direction, and gives an inertia in the ejection direction to the ink near the nozzle. An ink jet recording head that ejects ink droplets from nozzles, wherein the first driving means deflects the beam member to control the presence or absence of buckling reversal deformation of the beam member by the second driving means; in front Each beam-like ejector composed of an ink flow path member, the beam member, and the first driving means has lower rigidity at two locations at a predetermined distance from the substantially longitudinal center to the longitudinal direction than other portions. It is characterized by.

  In the invention of the above configuration, the rigidity at both ends of the flat portion is lowered while keeping the vicinity of the center in the longitudinal direction of the beam member flat, so that the second drive means is not bent at the center other than the center at the time of buckling reversal deformation. It is possible to regulate the ink droplet ejection direction by preventing deformation and asymmetric bending, and bending both sides while keeping the vicinity of the center flat.

  The ink jet recording head according to claim 6, wherein the bending operation of the second driving unit is stopped before the beam member is deformed so as to be convex from the concave in the ink droplet ejection direction, and then the bending operation is restarted again. The beam member is deformed so as to be convex from the concave in the ink droplet ejection direction.

  In the invention with the above configuration, by temporarily stopping the bending operation immediately before the buckling deformation, the bending shape variation of the beam is settled and the buckling deformation is caused after being stabilized, so that stable discharge performance can be obtained.

  The ink jet recording head according to claim 7 is joined to the ink flow path member to which ink is supplied, a nozzle that is formed substantially at the center of the ink flow path member and ejects ink droplets, and the ink flow path member. A beam member, a first driving means provided to be joined to the beam member and deflecting the beam member, two rotating members to which both ends in the length direction of the beam member are fixed, one end of the rotating member or Second driving means for holding both ends and rotating to deform the beam member so as to be convex from the concave in the ink droplet ejection direction, and the rotary member causes the beam member to be recessed from the concave in the ink droplet ejection direction. An ink jet recording head that is deformed to be convex and causes ink in the vicinity of the nozzles to be ejected as ink droplets by applying inertia in the ejection direction, wherein the first driving means deflects the beam member. Thus, the presence or absence of buckling reversal deformation of the beam member by the second driving means is controlled, and the nozzles in the ink flow path member are moved in the paper feeding direction as they move away from the second driving means on the rotating member. It is provided to be shifted.

  In the invention of the above configuration, by correcting the nozzle position according to the distance from the second driving means, the fixing member rotated by the second driving means causes torsional deformation with the distance from the second driving means, It is possible to correct the ejection timing of the ink droplets and align the landing positions of the ink droplets ejected from all the nozzles in the paper feeding direction.

  An ink jet recording head according to an eighth aspect of the invention is characterized in that the second drive means is provided at both longitudinal ends of the rotating member.

  In the invention having the above-described configuration, the second driving means is provided at both ends of the rotating member, so that the rotating member is less twisted and symmetric in the width direction.

  The ink jet recording head according to claim 9 is joined to the ink channel member, an ink channel member to which ink is supplied, a nozzle that is formed substantially at the center of the ink channel member and ejects ink droplets, and the ink channel member. A beam member, a first driving means provided to be joined to the beam member and deflecting the beam member, two rotating members to which both ends in the length direction of the beam member are fixed, one end of the rotating member or Second driving means for holding both ends and rotating to deform the beam member so as to be convex from the concave in the ink droplet ejection direction, and the rotary member causes the beam member to be recessed from the concave in the ink droplet ejection direction. An ink jet recording head that is deformed to be convex and causes ink in the vicinity of the nozzles to be ejected as ink droplets by applying inertia in the ejection direction, wherein the first driving means deflects the beam member. Thus, the presence or absence of buckling reversal deformation of the beam member by the second driving means is controlled, and the position of the nozzle in the ink flow path member is set to the position where the ink flow path member is held on the rotating member. The rotating member is provided so as to be shifted in the paper feeding direction as it approaches the center from both longitudinal ends.

  In the invention with the above configuration, the fixing member rotated by the second driving unit is adjusted according to the distance from the second driving unit by correcting the nozzle position according to the distance from both ends where the second driving unit is provided. It is possible to correct the ejection timing deviation of the ink droplets due to the twist deformation and align the landing positions of the ink droplets ejected from all the nozzles in the paper feeding direction.

  The ink jet recording head according to claim 10 is characterized in that the second driving means provided at both ends in the longitudinal direction of the rotating member are driven simultaneously.

  In the invention with the above configuration, by correcting the discharge timing according to the nozzle position and simultaneously driving the second driving unit, it is possible to reduce the variation in the amount of twist deformation of the fixing member rotated by the second driving unit. As a result, the deviation in ejection timing can be made symmetrical in the width direction, and variations in the landing positions of ink droplets can be reduced.

  The ink jet recording head according to an eleventh aspect is characterized in that the second driving means provided at both ends in the longitudinal direction of the rotating member are driven with a time difference.

  In the invention with the above configuration, the ejection timing is corrected by the nozzle position, and the second driving means is driven with a time difference (delay) corresponding to the torsional deformation speed of the fixing member. As a result, the variation in the torsional deformation amount of the fixing member rotated by the second driving means can be reduced, and the deviation in ejection timing, and hence the variation in the landing positions of the ink droplets, can be reduced.

  An ink jet recording apparatus according to a twelfth aspect uses the ink jet recording head according to the first to eleventh aspects.

  In the invention having the above-described configuration, since the ink jet recording head according to the first to eleventh aspects is used, high-viscosity ink can be discharged onto the recording medium. Compared with a conventional ink jet recording apparatus, it is possible to perform recording with excellent quality without bleeding.

  Since the present invention has the above-described configuration, an inkjet recording head and an inkjet recording apparatus with high ejection accuracy capable of ejecting high-viscosity ink at room temperature can be obtained.

  FIG. 1 shows an ink jet recording head according to a first embodiment of the present invention.

  As shown in FIGS. 1 (a) and 1 (b), an ink jet recording head 10 includes a hollow tube-shaped ink flow path member 12 having an ink flow path 13 therein and a nozzle 16 at substantially the center in the length direction, and an ink. The beam member 14 that supports the flow path member 12 is joined, and the holding member 18 supports both ends.

  A piezo element 30 is joined to the beam member 14, and a signal electrode 32 is joined to the piezo element 30, and the beam member 14, the piezo element 30, and the signal electrode 32 constitute an actuator 36. 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 signal electrode 32. An electrode pad 33 is provided at one end of the signal electrode 32, and is connected to a switching IC (not shown) by a wiring 34. 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 ink flow path member 12 can be bent in the ink discharge direction (upper direction in the drawing) and in the reverse direction, and the ink supplied from the ink pool 24 and reaches the nozzle 16 through the ink flow path 13 is ejected in the discharge direction by inertia. Discharge as drops.

  As described above, the ink used here prevents ink bleeding when landing on the medium, increases the optical color density, suppresses swelling of the medium by reducing the water content / short-time drying, or totals such high-quality ink. The ink viscosity is extremely high, specifically, a high viscosity ink having a viscosity much higher than 10 cps (for example, 50 to 100 cps) due to a large degree of freedom in designing.

  The holding member 18 is fixed to an arm 22 provided in the rotary encoder 20, and is pressed from both sides at a position offset from the rotation center of the rotary encoder 20 by the length of the arm 22, or a force is applied in the bending direction. The ink flow path member 12 joined to the beam member 14 is bent in the ink discharge direction or in the reverse direction.

  The holding member 18 may have a rod shape that is long in the front-rear direction of FIG. 1A or may have a ladder-like structure in which a plurality of ink flow path members 12 are provided on the holding member 18.

  FIG. 1B is a perspective view in which only the periphery of the nozzle 16 is cut out. As shown in FIG. 1B, the ink flow path member 12 has the following effects by arranging a plurality of hollow tube-shaped members and cutting out the nozzles 16 at substantially the same position in the length direction.

  That is, for example, in a head structure manufactured by laminating thin plates or film materials provided with nozzle holes, a multi-nozzle head cannot be manufactured at low cost / narrow pitch, but a large number of previously separated tubes are aligned to form a head array. This can be easily realized.

  In addition, compared with the flow path formed by the laminated structure, the flow path in the tube does not have an internal step or the like, and is excellent in ink filling properties and bubble discharge properties.

  The actual operation will be described below.

  FIG. 2 shows the operation of the ink jet recording head according to the first embodiment of the present invention.

  As shown in FIG. 2A, first, the rotary encoder 20 is reversed (rotated in the direction in which the ink flow path member 12 is stretched), and the ink flow path member 12 that is convex in the ejection direction in the initial state is straightened, It shall be in a state without bending.

  Next, as shown in FIG. 2B, when a signal instructing ejection to the ink flow path member 12 is sent from the switching IC, the actuator 36 is driven to bend so as to be concave in the ejection direction.

  Further, when the rotary encoder 20 is rotated forward in the direction of the arrow in FIG. 2 (c), the ink flow path member 12 is bent toward the convex in the discharge direction (upward in the drawing) gradually from the end closer to the rotary encoder 20, that is, from both ends. Change.

  When this change approaches the center from both ends, the ink flow path member 12 (or the beam member 14) undergoes a steep buckling reversal at a certain point and is rapidly deformed in the ink ejection direction (upper in the drawing) (FIG. 2). (D)).

  Since the nozzle 16 is provided substantially at the center in the length direction of the ink flow path member 12, the ink reaching the nozzle 16 is changed in the ejection direction of the ink flow path member 12 due to this buckling inversion. 16 is ejected as ink droplets 2.

  Further, in FIG. 2D, after the amount of bending becomes maximum and the rotary encoder 20 stops, the ink flow path member 12 is flattened by reverse rotation (FIG. 2A), so that the ink flow path member 12 is in the initial position. Returning to FIG.

  The deformation speed due to the buckling reversal is very large compared to the displacement caused by 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. is there.

  FIG. 3 shows an ink jet recording head according to the first embodiment of the present invention.

  When the ink droplet 2 is ejected as shown in FIG. 3A, the ink flow path member 12 (or the beam member 14) is buckled and reversed at the position where the nozzle 16 is removed from the center in the length direction. If it occurs, the ink droplet 2 is ejected in a state where the nozzle 16 is not directed in a desired direction. As a result, the ejection direction is deviated and the landing position on the paper is shifted.

  FIG. 3B schematically shows each beam-like ejector in the ink jet recording head according to the first embodiment of the present invention as seen from the ink discharge direction. Here, the ink flow path member 12 (or the beam member) is shown. The shape of 14) is shown.

  As shown in FIG. 3B, the rigidity of the vicinity of the nozzle 16 can be reduced by reducing the width of the ink flow path member 12 (or the beam member 14) only in the vicinity of the center where the nozzle 16 is provided.

  As a result, in the buckling reversal of the ink flow path member 12 (or the beam member 14), that is, when the ink droplet 2 is discharged, the ink flow path member 12 (or the beam member 14) easily bends in the vicinity of the nozzle 16. The landing position can be prevented from shifting.

  At this time, in addition to narrowing the width of the ink flow path member 12 or the beam member 14 or the actuator 36, the thickness is reduced, or the porous material is soaked with resin only at both ends to strengthen the center and both ends. The same effect can be obtained by providing a difference in the rigidity of the parts.

  FIG. 4 shows the operation of the ink jet recording head according to the first embodiment of the present invention.

  As shown in FIG. 4A, first, the rotary encoder 20 is reversed (rotates in the direction in which the ink flow path member 12 is stretched), and the ink flow path member 12 that is convex in the ejection direction is straightened, and there is no deflection. State. Since the actuator 36 is joined to the ink flow path member 12 (enlarged view 4D), the ink flow path member 12 can be bent concavely or convexly in the ejection direction by driving the actuator 36.

  Next, as shown in FIG. 4B, when a signal instructing ejection to the ink flow path member 12 is sent from a switching IC (not shown), the actuator 36 is driven, and the central portion of the ink flow path member 12 is recessed in the ejection direction. It will be in the state bent so that.

  At this time, as shown in the figure, since the ink flow path member 12 is thin only in the central part (or may be narrow in width), the ink flow path member 12 is low in rigidity and more flexible than many parts, so that the nozzle 16 does not bend asymmetrically. It deform | transforms so that the center vicinity in which it was provided may become concave.

  Further, when the rotary encoder 20 is rotated in the direction of the arrow in FIGS. 4B and 4C, the ink flow path member 12 is convex toward the direction closer to the rotary encoder 20, that is, gradually from both ends in the ejection direction (upward in the drawing). The bending direction changes.

  When this change approaches the center from both ends, the ink flow path member 12 (or the beam member 14) undergoes steep buckling reversal at a certain point, and is rapidly deformed in the ink discharge direction (upper in the drawing) (FIG. 4). (C)).

  At this time, as shown in the drawing, since the center portion of the ink flow path member 12 is bent, it is deformed so that the vicinity of the center where the nozzle 16 is provided is convex without being subjected to asymmetric buckling reversal deformation. As a result, the ink droplet 2 ejected from the nozzle 16 can be ejected in a desired direction.

  FIG. 5 shows an ink jet recording head according to a second embodiment of the present invention.

  FIG. 5A schematically shows each beam-like ejector. Here, the shape of the ink flow path member 12 (or the beam member 14) is shown. Thus, by narrowing the width of the ink flow path member 12 (or the beam member 14) only at both ends of the central portion 12c where the nozzle 16 is provided, the rigidity at both ends of the central portion 12c near the nozzle 16 is partially lowered. Can do.

  As a result, when the ink flow path member 12 (or the beam member 14) is buckled and reversed, that is, when the ink droplet 2 is discharged, the central portion 12c in the vicinity of the nozzle 16 moves at a high speed in the discharge direction while maintaining a flat shape. Sometimes, it is possible to prevent the ejection direction of the ink droplet 2 from going wrong and the landing position on the paper from deviating.

  At this time, in addition to narrowing the width of the ink flow path member 12 or the beam member 14 or the actuator 36, the central portion 12c is reduced by a method such as reducing the thickness, or impregnating the porous material with resin only at both ends. The same effect can be obtained by providing a difference in rigidity between the two ends.

  FIG. 6 shows the operation of the ink jet recording head according to the third embodiment of the present invention.

  In FIG. 6, changes in the operation of the ink jet recording head 17, the voltage applied to the actuator 36, and the operation of the rotary encoder 20 from immediately before the ink flow path member 12 undergoes buckling reversal to immediately after ink droplets are ejected. It is shown.

  In FIG. 6A, the rotary encoder 20 is driven in the reverse direction (direction in which the ink flow path member 12 is pulled from both ends), the ink flow path member 12 deformed by pressing is extended, and the ink flow path member 12 is returned to the initial state. There will be no deflection.

  Subsequently, in FIG. 6B, the rotary encoder 20 is stopped, and here, a signal instructing ejection is sent from the switching IC, and when the actuator 36 is driven, the ink flow path member 12 becomes concave in the ejection direction. Deflection occurs.

  When the deformation by the actuator 36 is completed and the ink flow path member 12 reaches a specified amount of deflection, the rotary encoder 20 is driven in the forward direction (direction in which the ink flow path member 12 is pressed from both ends) as shown in FIG. The direction in which the ink flow path member 12 is closer to the rotary encoder 20, that is, gradually changes from both ends to the convex in the ejection direction (upward in the drawing).

  At this time, the deformation by the rotary encoder 20 varies, and the amount of deflection of the ink flow path member 12 (beam member 14) fluctuates with respect to the amount of rotation of the rotary encoder 20 during a short time, so that the rampage is violated. Has occurred. Due to this influence, the deformation of the ink flow path member 12 (beam member 14) becomes low in reproducibility, and the ejection accuracy of the ink droplet 2 becomes low.

  Since the deformation variation is eliminated with time, in this embodiment, the rotary encoder 20 is temporarily stopped before discharge, that is, before buckling reversal occurs (between (c) and (d) in FIG. 6). As a result, the irregularity and variation of the bent shape of the ink flow path member 12 (beam member 14) is settled, and ejection can be performed in a stable state.

  When the change in the deflection of the ink flow path member 12 approaches the center from both ends, the ink flow path member 12 (or the beam member 14) undergoes a steep buckling reversal at a certain point (FIG. 6D), and the ink ejection direction ( Deforms rapidly to the top in the figure.

  At this time, since the ink inside the ink flow path member 12 tends to advance in the ejection direction at a constant speed due to inertia, the ink droplet 2 protrudes from the nozzle 16 due to the speed difference between the two. When the deformation of the beam member 14 reaches the maximum amount, the displacement in the ejection direction stops, so that only the ink droplet 2 protrudes from the nozzle 16 (FIG. 6D), and the ink droplet 2 is ejected in the ejection direction as it is according to inertia. It is.

  Here, the rotary encoder 20 stops and prepares for the next cycle. In the above embodiment, this series of operations was driven at 3 Hz per cycle, but the displacement due to the buckling reversal of the beam member 14 occurs in a short period of time, so that even in the present invention where the viscosity of the ink is high, good ejection is achieved. Performance is obtained.

  Further, as described above, the rotation of the rotary encoder 20 is temporarily stopped immediately before the buckling reversal, and the ejection accuracy is increased by performing ejection while the bent shape of the ink flow path member 12 (beam member 14) is stable. Can do.

  By the way, as shown in FIG. 7, when the holding member 18 is rotated by the rotary encoder 20 to deform the ink flow path member 12, the holding member 18 is applied with a force on the portion held by the rotary encoder 20, Torsional deformation occurs when the ink flow path member 12 (or the beam member 14 or the actuator 36 (not shown)) that resists the direction is rotated while suppressing deformation resistance.

  That is, when the deformation of the holding member 18 starts from the direction A in FIG. 7A and is transmitted in the B direction, a predetermined time is required until the rotation / deformation of the holding member 18 started in A is transmitted to the B. If the B-side end of the holding member 18 is held by a bearing 25 or the like having no power, the timing at which the rotation and deformation started at the A-side end deforms the ink flow path member 12 while twisting the holding member 18 gradually. Deformation occurs most late at the B side end.

  In other words, ink droplet ejection from the nozzle 16 due to buckling deformation also delays from the A side end to the B side end, so if printing is performed while the paper is passed as it is, the A side as shown in FIG. From the end toward the B-side end, a delay associated with the progress of the paper appears as an ink droplet landing position shift.

  That is, since the A side end is closest to the rotary encoder 20, the discharge timing is early, and the B side end is farthest from the rotary encoder 20, so that the discharge timing is late. The landing position will shift. As a result, an ejection pattern as shown in FIG.

  If the entire head is tilted as shown in FIG. 8 and the position of the nozzle 16 is shifted from the rotary encoder 20 in order to eliminate this landing position shift, the direction for correcting the discharge timing shift due to the twist of the holding member 18 is corrected. The position of the nozzle 16 can be moved. In this embodiment, since the distance between the nozzles 16 becomes dcos θ when the original distance between the nozzles 16 is d, the dot pitch needs to be corrected.

  Therefore, in this embodiment, the landing position deviation of the ink droplet due to the deviation of the ejection timing is corrected without changing the dot pitch.

  FIG. 9 shows an ink jet recording head according to a fourth embodiment of the present invention.

  As shown in FIG. 9A, the ink jet recording head 19 has a ladder-like structure in which holding members 18 support both ends of a plurality of ink flow path members 12 each having a nozzle 16 at the center in the length direction. Yes.

  One end of each of the two holding members 18 is provided with a rotary encoder 20, and the holding member 18 is rotated to cause the ink flow path member 12 to buckle and reversely deform. The ink flow path member 12 is provided with a nozzle 16 at substantially the center in the length direction, and ejects ink droplets by buckling deformation of the ink flow path member 12.

  The present embodiment is characterized in that the position of the nozzle 16 is shifted in the paper feeding direction (lower in the figure) as it moves away from the rotary encoder 20. In other words, assuming that the paper is fixed and ink droplets are ejected, the nozzle arrangement is as shown in FIG. 9B.

  This nozzle arrangement has a pattern for correcting landing position deviation due to ejection timing deviation caused by torsional deformation of the holding member 18, as shown in FIG. 7B.

  That is, without correction, the landing position shift occurs as shown in FIG. 10A due to the discharge timing shift, but the landing position shift is corrected by arranging the nozzles 16 in the discharge pattern as shown in FIG. As shown in FIG. 10 (b), a correct landing pattern as shown by the solid line can be obtained by correcting the deviation in the landing position of the dotted line with the nozzle arrangement of the one-dot chain line.

  However, at this time, the arrangement of the nozzles 16 is not simply reversed as shown in FIG. 7B, but the variation in time required until buckling inversion occurs due to the change in the distance from the holding member 18 to the nozzles 16 is taken into consideration. By inserting, more accurate correction can be performed.

  Alternatively, as shown in FIG. 11, when only one of the two holding members 18 is rotated by the rotary encoder 20 to deform the ink flow path member 12, the holding member 18 is held by the rotary encoder 20. Since the force is applied to the gripping portion only in the direction (upper in the figure), by rotating while suppressing the deformation resistance of the ink flow path member 12 (or the beam member 14 and the actuator 36 not shown) that becomes a resistance in the rotation direction. Torsional deformation occurs.

  That is, when the deformation of the holding member 18 starts from both directions A and B in FIG. 11A and is transmitted to the center, a predetermined time is required until the rotation / deformation of the holding member 18 started at both ends is transmitted to the center. Therefore, the timing at which the ink flow path member 12 is deformed while the rotation / deformation started at both ends causes the holding member 18 to be torsionally deformed is gradually delayed, and the deformation is most delayed at the center.

  In other words, the ink droplet ejection from the nozzle 16 due to buckling deformation also delays from both ends to the center, so if printing is performed while the sheet is passed as it is, the both ends toward the center as shown in FIG. The delay associated with the progress of the paper appears as a deviation in the landing position of the ink droplets.

  That is, both ends are closest to the rotary encoder 20, so that the discharge timing is early, and the center is farthest from the rotary encoder 20, so that the discharge timing is late, so that the landing position is behind the paper traveling direction (mesh arrow) (upper in the figure). It will shift. As a result, an ejection pattern as shown in FIG.

  Since this deviation is an upwardly convex shape such as a semicircle or a substantially parabolic shape, it cannot be corrected by the inclination of the head as shown in FIG. Therefore, in this embodiment, the landing position deviation of the ink droplet due to the deviation of the ejection timing is corrected by the arrangement of the nozzles 16.

  FIG. 12 shows an ink jet recording head according to a fifth embodiment of the present invention.

  As shown in FIG. 12A, the ink jet recording head 21 has a ladder-like structure in which holding members 18 support both ends of a plurality of ink flow path members 12 each having a nozzle 16 at the center in the length direction. Yes.

  One of the holding members 18 is provided with a rotary encoder 20 at each end, and the holding member 18 is rotated to buckle and reversely deform the ink flow path member 12. The ink flow path member 12 is provided with a nozzle 16 at substantially the center in the length direction, and ejects ink droplets by buckling deformation of the ink flow path member 12.

  The present embodiment is characterized in that the position of the nozzle 16 is shifted in the paper feeding direction (lower in the figure) as it moves away from both ends where the rotary encoder 20 is provided. That is, assuming that the paper is fixed and ink droplets are ejected, the nozzle arrangement is such that the ejection pattern is as shown in FIG.

  This nozzle arrangement has a pattern for correcting the landing position deviation due to the ejection timing deviation caused by the torsional deformation of the holding member 18 as shown in FIG.

  That is, without correction, the landing position shift is caused by the discharge timing shift as shown in FIG. 13A, but the landing position shift is corrected by arranging the nozzles 16 in the discharge pattern as shown in FIG. As shown in FIG. 13B, a correct landing pattern as shown by the solid line can be obtained by correcting the deviation in the landing position of the dotted line by the nozzle arrangement of the one-dot chain line.

  FIG. 14 shows the operation of the ink jet recording head according to the fifth embodiment of the present invention.

  First, as shown in FIG. 14A, the rotary encoder 20 reverses (rotates in the direction in which the ink flow path member 12 is stretched), and the ink flow path member 12 that is convex in the ejection direction is straightened, and there is no deflection. State. At this time, since the holding member 18 is held at one end by the rotary encoder 20 and the other end is held by the fixing member 23, deformation due to rotation of the rotary encoder 20 occurs from the side held by the rotary encoder 20 (right side in the figure). .

  Next, when a signal instructing ejection to the ink flow path member 12 is sent from the switching IC, the actuator is driven to bend so as to be concave in the ejection direction.

  Furthermore, when the rotary encoder 20 is rotated in the direction of the arrow in FIG. 14B, the ink flow path member 12 is bent closer to the rotary encoder 20, that is, gradually from the right end in the figure to the convex in the ejection direction (upward in the figure). Changes.

  Here, since the vicinity of the center in the length direction of the ink flow path member 12 is deformed so as to be concave in the discharge direction by an actuator 36 (not shown), the discharge direction (upper in the figure) except for the vicinity of the center as shown in the figure. The deflection direction changes to convex.

  When this change is closer to the rotary encoder 20, that is, from the right end in the figure to the center, the ink flow path member 12 (or the beam member 14) undergoes steep buckling reversal at a certain point, and the ink ejection direction (upper in the figure). ) (FIG. 14 (c)).

  Since the nozzle 16 is provided substantially at the center in the length direction of the ink flow path member 12, the ink reaching the nozzle 16 is changed in the ejection direction of the ink flow path member 12 due to this buckling inversion. 16 is ejected as ink droplets 2.

  Further, in FIG. 14C, after the amount of deflection becomes maximum and the rotary encoder 20 stops, the ink flow path member 12 is flattened by reverse rotation (FIG. 14A), so that the ink flow path member 12 is in the initial position. Returning to FIG.

  The amount of deformation due to this buckling reversal is very large compared to 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 ink droplets 2. . Further, since the actuator 36 is given initial deflection (concave in the ejection direction), the rotary encoder 20 can sufficiently buckle and reversely deform the ink flow path member 12 only on one side of the holding member 18.

  FIG. 15 shows another embodiment of the ink jet recording head according to the fifth embodiment of the present invention.

  As shown in FIG. 15A, the ink jet recording head 21 has a ladder-like structure in which the holding members 18 respectively support both ends of the plurality of ink flow path members 12 provided with the nozzles 16 at substantially the center in the length direction. Yes.

  The two holding members 18 are respectively provided with rotary encoders 20 at both ends, and rotate the holding member 18 to buckle and reversely deform the ink flow path member 12. The ink flow path member 12 is provided with a nozzle 16 at substantially the center in the length direction, and ejects ink droplets by buckling deformation of the ink flow path member 12.

  At this time, the rotary encoder 20 may be driven by giving a time difference between the rotary encoders 20A and 20B instead of simultaneously driving at both ends of the holding member 18. For example, driving of the rotary encoder 20A may be started first, and 20B may be driven with a time difference with a delay corresponding to the torsional deformation speed. Also in this case, the torsional deformation of the holding member 18 proceeds from the right to the left in the drawing similarly to FIG. 7, so that the discharge pattern is also delayed from the right to the left as shown in FIG. 7B.

  Therefore, in the present embodiment, the position of the nozzle 16 is shifted in the paper feeding direction (lower in the figure) as it moves away from both ends where the rotary encoder 20 is provided. In other words, assuming that the paper is fixed and ink droplets are ejected, the nozzle arrangement is as shown in FIG. 9B.

  This nozzle arrangement has a pattern for correcting landing position deviation due to ejection timing deviation caused by the time difference between the rotary encoders 20A and 20B.

  That is, the landing position shift is caused by the discharge timing shift without correction, but the landing position shift can be corrected by setting the arrangement of the nozzles 16 to a pattern as shown in FIG. 15A to obtain a correct landing pattern. In this embodiment, since the rotary encoders 20 provided at both ends of the two holding members 18 are driven with a time difference, the rotary encoders 20 are provided only at both ends of the holding member 18 on one side (see FIG. 9). ), The amount of variation in the discharge timing can be reduced. For this reason, although it becomes a comparatively complicated structure which drives the two holding members 18, it has the effect that a landing position can be made highly accurate.

  However, at this time, the arrangement of the nozzles 16 is not simply reversed in the landing position shift, but takes into account the variation in time required for buckling reversal to occur due to a change in the distance from the holding member 18 to the nozzles 16. As in the fourth embodiment, more accurate correction can be performed.

  Alternatively, the rotary encoders 20 provided at both ends of the two holding members 18 may be driven simultaneously. That is, if the rotary encoders 20A and 20B are driven simultaneously as shown in FIG. 15B, the deformation of the holding member 18 starts from both directions A and B in FIG. Since a predetermined time is required until the rotation / deformation 18 is transmitted to the center, the timing at which the ink flow path member 12 is deformed while the rotation / deformation started at both ends is twisting the holding member 18 is gradually delayed. In the center, deformation occurs most late.

  In other words, ink droplet ejection from the nozzle 16 due to buckling deformation also delays from both ends to the center, so if printing is performed while passing the paper as it is, there is a delay accompanying the progress of the paper from both ends toward the center. Appears as an ink droplet landing position misalignment.

  That is, both ends are closest to the rotary encoder 20, so that the discharge timing is early, and the center is farthest from the rotary encoder 20, so that the discharge timing is late. It will shift.

  Therefore, in the present embodiment, the ink droplet landing position deviation due to the ejection timing deviation is corrected by arranging the nozzles 16 as shown in FIG. In this embodiment, since the rotary encoders 20 provided at both ends of the two holding members 18 are driven simultaneously, the rotation encoder 20 is provided only at both ends of the holding member 18 on one side (see FIG. 12). Thus, the absolute amount of ejection timing deviation can be reduced. For this reason, although it becomes a comparatively complicated structure which drives the two holding members 18, it has the effect that the dispersion | variation in deviation | shift amount can be reduced.

  In this case as well, the arrangement of the nozzles 16 is not simply made the reverse of the landing position deviation, but by taking into account fluctuations in the time required for buckling reversal to occur due to changes in the distance from the holding member 18 to the nozzles 16. More accurate correction can be performed as in the fourth embodiment.

  FIG. 16 shows an ink jet recording apparatus using the ink jet recording head according to the present invention.

  As shown in FIG. 16, the inkjet recording apparatus 50 includes a head holding member 54, and the inkjet recording head 10 or 21 of the present invention is held by the head holding member 54. The head holding member 54 has a structure that holds the ink jet recording heads 10 and 21 and does not disturb the ink discharge operation. Under the head holding member 54, a table 52 for placing and holding the recording medium P is provided.

  The recording medium P is set on the table 52, and the table 52 is moved in the X and Y directions (white arrows in the figure) in the plane, and the ink jet recording head 10 or 21 is driven to eject ink droplets 2 of high viscosity ink. Discharge. Since high-viscosity ink is used as described above, bleeding of the ink droplet 2 when landing on the recording medium P can be prevented, and high-quality recording can be performed.

  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.

  Moreover, in the said embodiment, although the ink flow path member 12 and the beam member 14 were each formed and joined with separate materials, it is not limited to this. For example, the beam member 14 may be included in the ink flow path member 12 or may be an integral structure. Alternatively, other forms may be used.

  In the above embodiment, the inkjet recording head 10 or 21 is fixed and recording is performed while moving the recording medium P. For example, the recording medium P is fixed and the inkjet recording head 10 or 21 is mounted on the carriage. Recording may be performed while being conveyed, or recording may be performed while conveying both. Alternatively, the recording medium P may be wound around a drum and rotated.

  In addition, the inkjet recording in the present specification is not limited to recording characters and images on recording paper. That is, the recording medium is not limited to paper, and the liquid to be ejected is not limited to ink. For example, industrial use 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 droplet ejecting apparatuses.

It is a figure which shows the inkjet recording head which concerns on the 1st form of this invention. It is a figure which shows operation | movement of the inkjet recording head which concerns on the 1st form of this invention. It is a figure which shows operation | movement of the inkjet recording head which concerns on the 1st form of this invention. It is a figure which shows operation | movement of the inkjet recording head which concerns on the 1st form of this invention. It is a figure which shows operation | movement of the inkjet recording head which concerns on the 2nd form of this invention. It is a figure which shows operation | movement of the inkjet recording head which concerns on the 3rd form of this invention. It is a figure which shows the structure of the conventional inkjet recording head. It is a figure which shows the structure of the conventional inkjet recording head. It is a figure which shows the inkjet recording head which concerns on the 4th form of this invention. It is a figure which shows operation | movement of the inkjet recording head which concerns on the 4th form of this invention. It is a figure which shows the structure of the conventional inkjet recording head. It is a figure which shows the inkjet recording head which concerns on the 5th form of this invention. It is a figure which shows operation | movement of the inkjet recording head which concerns on the 5th form of this invention. It is a figure which shows operation | movement of the inkjet recording head which concerns on the 5th form of this invention. It is a figure which shows the modification of the inkjet recording head which concerns on the 5th form of this invention. It is a figure which shows the inkjet recording device which concerns on this invention. It is a figure which shows the conventional inkjet recording head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet recording head 15 Inkjet recording head 17 Inkjet recording head 19 Inkjet recording head 21 Inkjet recording head 12 Ink flow path member 13 Ink flow path 14 Beam member 16 Nozzle 18 Holding member 20 Rotary encoder 25 Bearing 30 Piezo element

Claims (12)

An ink flow path member to which ink is supplied;
A nozzle formed at substantially the center of the ink flow path member for discharging ink droplets;
A beam member joined to the ink flow path member;
A first driving means provided to be joined to the beam member and deflecting the beam member;
Second driving means for bending the end of the beam member and deforming the beam member so as to be convex from the concave in the ink droplet ejection direction;
An ink jet recording head in which the second driving means deforms the beam member from a concave to a convex in the ink droplet ejection direction, and ejects ink in the vicinity of the nozzle as ink droplets by applying inertia in the ejection direction; There,
The first driving means deflects the beam member to control the presence or absence of buckling reversal deformation of the beam member by the second driving means,
Each of the beam-like ejectors comprising the ink flow path member, the beam member, and the first drive means has a rigidity in the vicinity of the center in the longitudinal direction lower than that in the vicinity of both ends in the longitudinal direction.   2. The ink jet recording head according to claim 1, wherein a width at a substantially center in a length direction of the beam member is narrowed.   3. The ink jet recording head according to claim 1, wherein a width at a substantially center in a length direction of the ink flow path member is narrowed.   In each of the beam-like ejectors, one or both of the ink flow path member, the first driving unit, and the beam member have a thickness in the vicinity of a substantially central portion in the longitudinal direction that is thinner than that in the vicinity of both ends in the longitudinal direction. The ink jet recording head according to any one of claims 1 to 3. An ink flow path member to which ink is supplied;
A nozzle formed at substantially the center of the ink flow path member for discharging ink droplets;
A beam member joined to the ink flow path member;
A first driving means provided to be joined to the beam member and deflecting the beam member;
Second driving means for bending the end of the beam member and deforming the beam member so as to be convex from the concave in the ink droplet ejection direction;
An ink jet recording head in which the second driving means deforms the beam member from a concave to a convex in the ink droplet ejection direction, and ejects ink in the vicinity of the nozzle as ink droplets by applying inertia in the ejection direction; There,
The first driving means deflects the beam member to control the presence or absence of buckling reversal deformation of the beam member by the second driving means,
Each beam-like ejector composed of the ink flow path member, the beam member, and the first driving means has a lower rigidity than the other portions at a predetermined distance from the substantially longitudinal center to the longitudinal direction. An ink jet recording head.   Before the beam member is deformed from concave to convex in the ink droplet ejection direction, the bending operation of the second driving means is stopped, and then the bending operation is resumed, and the beam member is moved in the ink droplet ejection direction. The ink jet recording head according to claim 1, wherein the ink jet recording head is deformed so as to be convex from a concave. An ink flow path member to which ink is supplied;
A nozzle formed at substantially the center of the ink flow path member for discharging ink droplets;
A beam member joined to the ink flow path member;
A first driving means provided to be joined to the beam member and deflecting the beam member;
Two rotating members to which both longitudinal ends of the beam member are fixed;
Second driving means for holding one end or both ends of the rotating member and rotating the beam member to deform the beam member from concave to convex in the ink droplet ejection direction;
An inkjet recording head in which the rotating member deforms the beam member so as to be convex from a concave in the ink droplet ejection direction, and ejects ink droplets as ink droplets from the nozzle by applying inertia in the ejection direction to the ink in the vicinity of the nozzle. ,
The first driving means deflects the beam member to control the presence or absence of buckling reversal deformation of the beam member by the second driving means,
An ink jet recording head, wherein the nozzle in the ink flow path member is provided so as to be shifted in a paper feeding direction as the nozzle is separated from the second driving means on the rotating member.   The ink jet recording head according to claim 7, wherein the second driving unit is provided at both longitudinal ends of the rotating member. An ink flow path member to which ink is supplied;
A nozzle formed at substantially the center of the ink flow path member for discharging ink droplets;
A beam member joined to the ink flow path member;
A first driving means provided to be joined to the beam member and deflecting the beam member;
Two rotating members to which both longitudinal ends of the beam member are fixed;
Second driving means for holding one end or both ends of the rotating member and rotating the beam member to deform the beam member from concave to convex in the ink droplet ejection direction;
An inkjet recording head in which the rotating member deforms the beam member so as to be convex from a concave in the ink droplet ejection direction, and ejects ink droplets as ink droplets from the nozzle by applying inertia in the ejection direction to the ink in the vicinity of the nozzle. ,
The first driving means deflects the beam member to control the presence or absence of buckling reversal deformation of the beam member by the second driving means,
The nozzle position in the ink flow path member is provided so as to be shifted in the paper feeding direction as the position where the ink flow path member is held on the rotating member approaches the center from both longitudinal ends of the rotating member. An ink jet recording head.   The ink jet recording head according to claim 7 or 9, wherein the second driving means provided at both ends in the longitudinal direction of the rotating member are driven simultaneously.   10. The ink jet recording head according to claim 7, wherein the second driving means provided at both ends in the longitudinal direction of the rotating member are driven with a time difference.   An ink jet recording apparatus using the ink jet recording head according to any one of claims 1 to 11.

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