JP2009107164A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jet recording head which can absorb a pressure variation by a pressure wave generated at the time of ejection of a recording liquid, and to provide a liquid jet recorder which carries this. <P>SOLUTION: In the inkjet head, a plurality of chambers which communicate with nozzle openings and are filled with ink are arranged side by side in a piezoelectric ceramic plate, electrodes are prepared on sidewalls of both sides of each chamber, and a channel forming member 23 which supplies the ink to each chamber is installed. The inkjet head which discharges the ink filled inside the chamber out of the nozzle opening by changing a capacity of the chamber is equipped with an ink stable chamber 36 at an end part of the chamber side of the channel forming member. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a recording unit having an inkjet head, for example, applied to a printer, a fax machine, and the like, and an inkjet recording apparatus using the recording unit, and in particular, stable ink ejection characteristics by absorbing pressure fluctuations generated in a chamber. The present invention relates to an ink jet head from which can be obtained.

  2. Description of the Related Art Conventionally, an ink jet recording apparatus that records characters and images on a recording medium using an ink jet head having a plurality of nozzles that eject ink is known. In such an ink jet recording apparatus, the nozzle of the ink jet head is provided in the head holder so as to face the recording medium, and this head holder is mounted on the carriage so as to be scanned in a direction orthogonal to the transport direction of the recording medium. It has become.

  FIG. 8 shows a cross section of the main part of such an ink jet head.

  As shown in FIG. 8, a plurality of chambers 28 are arranged in parallel on the piezoelectric ceramic plate 26, and each chamber 28 is separated by a side wall 29. One end of each chamber 28 in the longitudinal direction extends to one end surface of the piezoelectric ceramic plate 26, and the other end does not extend to the other end surface, and the depth gradually decreases. An electrode 30 for applying a driving electric field is formed on the opening side surface of both side walls 29 in each chamber 28 in the longitudinal direction.

  A cover plate 31 is bonded to the opening side of the chamber 28 of the piezoelectric ceramic plate 26 via an adhesive 109. The cover plate 31 has a common ink chamber 32 that is a recess communicating with the other shallow end of each chamber 28, and an ink supply port 33 that penetrates from the bottom of the common ink chamber 32 in the direction opposite to the chamber 28. And have.

  Further, a nozzle plate 34 is joined to an end surface of the joined body of the piezoelectric ceramic plate 26 and the cover plate 31 where the chamber 28 is open, and the nozzle plate 34 has a nozzle opening at a position facing each chamber 28. 27 is formed.

  A wiring board is fixed to the surface of the piezoelectric ceramic plate 26 opposite to the nozzle plate 34 and opposite to the cover plate 31. On the wiring board, wirings connected to the respective electrodes 30 by bonding wires 121 and the like are formed, and a driving voltage can be applied to the electrodes 30 through the wirings.

  In the head chip 21 configured as described above, when each chamber 28 is filled with ink from the ink supply port 33 and a predetermined driving electric field is applied to the side walls 29 on both sides of the predetermined chamber 28 via the electrodes 30, The side wall 29 is bent and deformed to temporarily change the volume in the chamber 28, whereby the ink in the chamber 28 is ejected from the nozzle opening 27.

  For example, as shown in FIG. 9, when ink is ejected from the nozzle opening 27 corresponding to the chamber 28a, a positive drive voltage is applied to the electrodes 30a and 30b in the chamber 28a and the electrodes 30c facing each other are applied. , 30d is grounded. As a result, a drive electric field in the direction toward the chamber 28a acts on the side walls 29a and 29b. If this is orthogonal to the polarization direction of the piezoelectric ceramic plate 26, the side walls 29a and 29b are bent and deformed in the direction of the chamber 28a due to the piezoelectric thickness slip effect. As a result, the volume in the chamber 28a decreases, the pressure on the ink increases, and the ink is ejected from the nozzle openings 27.

2 and FIG. 8, the flow path forming member 23 is used when ink is supplied to each chamber in such an ink jet head. In the flow path forming member 23, ink is supplied to each chamber 28 by flowing ink from the ink inlet 18 to the ink outlet 19 communicating with the ink supply port 33 and each chamber 28. 3 is a side view of the flow path forming member 23, FIG. 4 is a front view of the flow path forming member 23, and FIG. 5 is a cross-sectional view taken along the line BB of the flow path forming member 23 shown in FIG.
JP 2002-331661 A

However, in recent years, in particular, an inkjet head having such a structure tends to increase the printing speed, and the number of nozzles tends to increase with the driving frequency. Along with the increase in the number of nozzles, the amount of ink supplied also increases, and ejection failure due to adverse effects on ink droplet ejection characteristics due to pressure fluctuations in the chamber is regarded as a problem.
The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and is equipped with a liquid jet recording head capable of absorbing pressure fluctuations due to pressure waves generated in a chamber when recording liquid is discharged. An object of the present invention is to realize a liquid jet recording apparatus.

  According to a first aspect of the present invention for solving the above problem, a plurality of chambers which are connected to a nozzle opening and filled with ink are arranged in parallel on a piezoelectric ceramic plate, and electrodes are provided on the side walls on both sides of each chamber. A flow path forming member that supplies ink to each chamber by flowing ink from the ink inlet to the ink outlet that communicates with the ink outlet is installed. By changing the volume of the chamber, the ink filled in the nozzle is opened. In the ink jet head that discharges from the ink jet head, the ink stabilizing chamber is provided at the ink outlet of the flow path forming member, thereby suppressing the pressure fluctuation generated in the chamber.

  In the first aspect, by providing an ink stabilizing chamber at the ink outlet that communicates with each chamber, it is possible to absorb pressure fluctuations caused by pressure waves generated in the chamber when the recording liquid is ejected.

  According to a second aspect of the present invention, in the first aspect, the height T of the ink stabilizing chamber is in a range of 0.3 × channel width X ≦ T ≦ 7 × channel width X. In the head.

  In the second aspect, by providing the height T of the ink stabilizing chamber in the above range, the height of the ink stabilizing chamber can be sufficient to suppress the pressure fluctuation generated in each chamber.

  A third aspect of the present invention is characterized in that, in the first aspect or the second aspect, the width W of the ink stabilizing chamber satisfies a relationship of N ≦ W ≦ (N + 10 mm) with respect to the discharge nozzle length N. In the inkjet head.

  In the third aspect, by providing the width W of the ink stabilizing chamber in the above range, the width of the ink stabilizing chamber can be sufficient to suppress the pressure fluctuation generated in each chamber.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the angle θ of the inclined portion of the ink stabilizing chamber is between 2 degrees ≦ θ ≦ 45 degrees. In the characteristic inkjet head.

  In the fourth aspect, by providing the angle θ of the inclined portion of the ink stabilizing chamber in the above range, the angle θ of the inclined portion of the ink stabilizing chamber is sufficient to suppress the pressure fluctuation generated in each chamber. be able to.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the width L of the ink stabilizing chamber is in a range of flow path width X ≦ L ≦ 10 × flow path width X. An inkjet head is characterized in that there is.

  In the fifth aspect, by providing the width L of the ink stabilization chamber in the above range, the width L of the ink stabilization chamber sufficient to suppress the pressure fluctuation generated in each chamber can be provided.

  According to a sixth aspect of the present invention, in the ink jet head according to any one of the first to fifth aspects, a filter is provided in the ink stabilizing chamber.

  In the sixth aspect, by providing the filter in the ink stabilizing chamber, it is possible to effectively suppress the pressure fluctuation generated in each chamber.

  A seventh aspect of the present invention is an ink jet head according to any one of the first to sixth aspects, wherein an absorber is installed in the ink stabilizing chamber.

  In the seventh aspect, by providing the absorber in the ink stabilizing chamber, the pressure fluctuation generated in each chamber can be effectively suppressed.

  According to an eighth aspect of the present invention, there is provided an ink jet recording apparatus comprising the ink jet head according to any one of the first to seventh aspects.

  As described above, according to the present invention, it is possible to provide an inkjet recording apparatus that enables stable ejection by absorbing and reducing pressure fluctuations in the ink liquid chamber, and enables high-speed and high-quality printing by simultaneously driving a large number of nozzles. it can.

  Hereinafter, the present invention will be described based on embodiments of the present invention.

  FIG. 1 is a schematic diagram of an ink jet recording apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, an ink jet recording apparatus 10 according to the present embodiment is a serial ink jet recording apparatus in which a head is scanned, and includes a head unit 100 provided with an ink jet head 20 that ejects ink. . The head unit 100 is fixed on a carriage 11, and the carriage 11 is mounted on a pair of guide rails 12a and 12b so as to be movable in the axial direction.

  Further, a drive motor 13 is provided on one end side of the guide rails 12a and 12b, and a driving force by the drive motor 13 is generated by a pulley 14a connected to the drive motor 13 and the other ends of the guide rails 12a and 12b. It is moved along the timing belt 15 that is stretched between the pulley 14b provided on the side.

  Further, a pair of transport rollers 16 and 17 are provided along the guide rails 12a and 12b on both ends in the direction orthogonal to the transport direction of the carriage 11, respectively. These transport rollers 16 and 17 transport the recording medium S below the carriage 11 in a direction perpendicular to the transport direction of the carriage 11.

  The carriage 11 scans the carriage 11 in a direction orthogonal to the feeding direction while feeding the recording medium S by the transport rollers 16 and 17, whereby characters, images, and the like are recorded on the recording medium S by the inkjet head 20. .

  Here, an example of an inkjet head that ejects ink will be described with reference to FIG. Note that the structure shown in FIG. 8 is the same as the conventional one.

  First, the head chip 21 will be described in detail. The piezoelectric ceramic plate 26 constituting the head chip 21 is provided with a plurality of chambers 28 communicating with the nozzle openings 27 and ejecting ink. The chambers 28 are separated by side walls 29.

  One end of each chamber 28 in the longitudinal direction extends to one end surface of the piezoelectric ceramic plate 26, and the other end does not extend to the other end surface, and the depth gradually decreases. Each chamber 28 is formed by, for example, a disk-shaped die cutter, and a portion where the depth gradually decreases is formed using the shape of the die cutter.

  In addition, a pair of individual electrodes 30 to which an independent drive signal is output for each chamber 28 are formed on the opening side surfaces of the side walls 28 on both sides in each chamber 28 in the longitudinal direction. The pair of individual electrodes 30 is formed on each side wall 29 in each chamber 28, for example, by vapor deposition from a known oblique direction.

  Further, a cover plate 31 is joined to the opening side of the chamber 28 of the piezoelectric ceramic plate 26. The cover plate 31 includes a common ink chamber 32 that is a recess that communicates only with the shallower other end of each chamber 28, and an ink supply port that penetrates from the bottom of the common ink chamber 32 in the opposite direction to the chamber 28. 33 is provided.

  The cover plate 31 can be formed of, for example, a ceramic plate, a metal plate, or the like, but considering the deformation after joining with the piezoelectric ceramic plate 26, a ceramic plate having an approximate thermal expansion coefficient is used. preferable.

  In addition, a nozzle plate 34 is joined to an end face where the chamber 28 of the joined body of the piezoelectric ceramic plate 26 and the cover plate 31 is opened. Nozzle openings 27 are formed at positions facing the chambers 28 of the nozzle plate 34.

  Furthermore, the nozzle plate 34 is larger than the area of the end surface where the chamber 28 of the joined body of the piezoelectric ceramic plate 26 and the cover plate 31 is opened. The nozzle plate 34 is formed by forming a nozzle opening 27 on a polyimide film or the like using, for example, an excimer laser device. Although not shown, a water repellent film having water repellency is provided on the surface of the nozzle plate 34 facing the substrate to prevent ink from adhering.

  In the present embodiment, a nozzle support plate (not shown) is disposed around the end portion where the chamber 28 of the joined body of the piezoelectric ceramic plate 26 and the cover plate 31 is opened. This nozzle support plate (not shown) is joined to the outside of the joined body end face of the nozzle plate 34 to stably hold the nozzle plate 34.

  Here, the ink jet head 20 having such a head chip (not shown) will be described in detail with reference to FIGS. Note that the structure shown in FIG. 2 is the same as the conventional one.

  As shown in FIGS. 2 and 8, the inkjet head 20 has a pair of piezoelectric ceramic plates 26 constituting a head chip (not shown) on the opposite end to the nozzle opening 27 side, for example, via a bonding wire. A wiring pattern (not shown) connected to the individual electrode 30 is formed.

  Further, on the rear end side of the nozzle support plate of the joined body of the piezoelectric ceramic plate 26 and the cover plate 31, an aluminum base plate 22 on the piezoelectric ceramic plate 26 side and a flow path forming member 23 on the cover plate 31 side are provided. Assembled. The flow path forming member 23 is provided with an ink introduction path that communicates with each of the ink supply ports 33 of the cover plate 31.

  The base plate 22 and the flow path forming member 23 are fixed by means such as an adhesive, and sandwich the joined body of the piezoelectric ceramic plate 26 and the cover plate 31 therebetween.

  A wiring board 25 is fixed on the base plate 22 protruding to the rear end side of the piezoelectric ceramic plate 26. A drive circuit having a drive IC for driving a head chip (not shown) is mounted on the wiring board 25, and a drive circuit and a flexible cable described later are connected via an anisotropic conductive film. Thereby, the inkjet head 20 is completed.

  FIG. 6 is a configuration diagram of a flow path forming member including an ink stabilizing chamber of the inkjet head according to the embodiment of the present invention. 7A shows a cross-sectional view taken along the line AA of the flow path forming member of FIG. 6, and FIG. 7B shows a cross sectional view taken along the line BB of the flow path forming member of FIG. 7B indicates the direction in which the ink flows.

  As shown in FIGS. 7A and 7B, the ink jet head according to the embodiment of the present invention supplies ink from the ink inlet 18 to the ink outlet 19 communicating with each chamber (not shown) when supplying ink to each chamber. In the flow path forming member 23 that supplies ink to each chamber by flowing, an ink stabilizing chamber 36 is provided at the ink outlet 19 immediately before the ink flows into the chamber.

  In the present invention, since the ink stabilization chamber 36 having a larger volume than the chamber suppresses pressure fluctuations generated in the chamber, crosstalk, deflection, and the like between adjacent chambers due to fluctuations in the ink flow rate that occur during ink ejection. Discharge defects such as missing dots can be prevented, and discharge stability and high print quality can be ensured. In addition, since the ink stabilization chamber 36 can store a large amount of ink near the chamber, it prevents ejection defects such as missing dots and deflection due to insufficient ink supply even in a situation where the ink viscosity has increased such as in a low temperature environment. And stable continuous printing can be realized.

  Hereinafter, the best mode of the ink stabilizing chamber 36 will be described in detail with reference to FIG. 7B.

  If the height T of the ink stabilization chamber 36 is 0.3 × channel width X> T, the ink stabilization chamber 36 is too small to suppress pressure fluctuations generated in a chamber (not shown). Therefore, this range is not preferable. Further, when T is T> 7 × channel width X, the amount of ink in the ink stabilization chamber 36 is large, and therefore the ink in the ink stabilization chamber 36 receives a large inertia force when the inkjet head (not shown) moves to the left and right. This is not preferable because a pressure fluctuation is given to a chamber (not shown) communicating with the ink stabilizing chamber 36. From the above, it is most desirable that the height T of the ink stabilizing chamber is 0.3 × channel width X ≦ T ≦ 7 × channel width X.

  If the width W of the ink stabilizing chamber 36 is N> W with respect to the discharge nozzle length N, it is desirable because the ink stabilizing chamber 36 can capture all pressure fluctuations generated in a chamber (not shown) and cannot suppress pressure fluctuations. Absent. Further, if W is W> (N + 10 mm), it is not preferable because pressure fluctuation is given to a chamber (not shown) due to the influence of the inertial force of the ink inside the ink stabilizing chamber 36. Therefore, it is most desirable that the width W of the ink stabilizing chamber has a relationship of N ≦ W ≦ (N + 10 mm).

  When the angle θ of the inclined portion of the ink stabilization chamber 36 is 2 degrees> θ, bubbles are accumulated inside the ink stabilization chamber 36 when ink is filled, and the contact area between the ink stabilization chamber 36 and a chamber (not shown) is reduced. The effect of pressure suppression is reduced. Therefore, 2 degrees> θ is not preferable. Further, if θ> 45 degrees, the space of the ink stabilizing chamber 36 becomes large, and pressure fluctuations are given to a chamber (not shown) due to the influence of the inertial force of the ink inside the ink stabilizing chamber 36, which is not preferable. From the above, it is desirable that the angle θ of the inclined portion is in the range of 2 degrees ≦ θ ≦ 45 degrees.

  If the width L of the ink stabilization chamber 36 satisfies the flow path width X> L, the ink stabilization chamber is too small to suppress pressure fluctuations generated in a chamber (not shown). Therefore, this range is not preferable. Further, if L is L> 10 × channel width X, it is not preferable because pressure fluctuation is given to a chamber (not shown) due to the influence of the inertial force of the ink inside the ink stabilizing chamber 36. From the above, it is most desirable that the width L of the ink stabilizing chamber 36 satisfies the flow path width X ≦ L ≦ 10 × the flow path width X.

  If a filter (not shown) is installed in the ink stabilization chamber 36, pressure fluctuations in the chamber (not shown) can be more effectively suppressed than in the case where there is no filter. Therefore, it is desirable to install a filter in the ink stabilization chamber 36.

  If an absorber (not shown) is installed in the ink stabilization chamber 36, pressure fluctuations in the chamber (not shown) can be more effectively suppressed than when no absorber is provided. Therefore, it is desirable to install an absorber in the ink stabilization chamber 36.

  By installing such a flow path forming member provided with the ink stabilization chamber 36 in the ink jet head 20 as shown in FIGS. 1 and 2, the pressure fluctuation generated in the chamber has a larger volume than the chamber. Since the stable chamber is suppressed, ejection defects such as crosstalk, deflection, and missing dots can be prevented, and ejection stability and high print quality can be ensured. In addition, the ink stabilization chamber can store a large amount of ink close to the chamber, so that even when the ink viscosity is increased such as in a low-temperature environment, ejection defects such as missing dots and deflection due to insufficient ink supply can be suppressed. And stable continuous printing is possible.

1 is a schematic diagram of an ink jet recording apparatus according to Embodiment 1 of the present invention. 1 is an exploded perspective view of an inkjet head according to Embodiment 1 of the present invention. It is a side view of the flow-path formation member which concerns on a prior art. It is a front view of the flow-path formation member which concerns on a prior art. It is sectional drawing of the flow-path formation member which concerns on a prior art. It is a side view of the channel formation member concerning Embodiment 1 of the present invention. It is sectional drawing of the flow-path formation member which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the outline | summary of the head chip of the inkjet head which concerns on a prior art. It is sectional drawing which shows the outline | summary of the head chip of the inkjet head which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet recording apparatus 11 Carriage 12 Guide rail 14 Pulley 18 Ink inlet 19 Ink outlet 20 Inkjet head 21 Head chip 22 Base plate 23 Flow path forming member 25 Wiring board 26 Piezoelectric ceramic plate 27 Nozzle opening 28 Chamber 29 Side wall 30 A pair of Individual electrode 31 Cover plate 32 Common ink chamber 33 Ink supply port 34 Nozzle plate 36 Ink stabilization chamber 100 Head unit 105 Electrode 109 Adhesive

Claims (8)

A plurality of chambers that are connected to the nozzle opening and filled with ink are arranged in parallel on the piezoelectric ceramic plate, and electrodes are provided on the side walls on both sides of each chamber, and ink is supplied from the ink inlet to the ink outlet that communicates with each chamber. In an ink jet head that has a flow path forming member for supplying ink to each chamber by flowing, and discharges ink filled in the chamber from the nozzle opening by changing the volume of the chamber,
An ink jet head, wherein an ink stabilizing chamber is provided at the ink outlet of the flow path forming member to suppress pressure fluctuations generated in the chamber.   2. The ink jet head according to claim 1, wherein the height T of the ink stabilizing chamber is in the range of 0.3 * channel width X≤T≤7 * channel width X.   3. The ink jet head according to claim 1, wherein the width W of the ink stabilizing chamber satisfies a relationship of N ≦ W ≦ (N + 10 mm) with respect to the discharge nozzle length N. 4.   4. The ink jet head according to claim 1, wherein an angle θ of the inclined portion of the ink stabilizing chamber is between 2 degrees ≦ θ ≦ 45 degrees.   5. The ink jet head according to claim 1, wherein a width L of the ink stabilizing chamber is in a range of channel width X ≦ L ≦ 10 × channel width X. 6.   6. The ink jet head according to claim 1, wherein a filter is installed in the ink stabilizing chamber.   7. The ink jet head according to claim 1, wherein an absorber is installed in the ink stabilizing chamber.   An ink jet recording apparatus comprising the ink jet head according to claim 1.

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