Electrostatic inkjet head and printing device

Abstract

An electrostatic inkjet head is an electrostatic inkjet head in which liquid in a nozzle is ejected by electrostatic attraction, and includes a main body portion in which a plurality of nozzles are arranged, a first electrode that applies a pulse voltage that charges the liquid, and a first shielding member that is disposed inside the main body portion along an ejection direction of the liquid and shields an electric field generated by the first electrode, the first shielding member having end portions on opposite sides in the ejection direction, the end portions being located on the opposite sides of the first electrode, and mutually adjacent ones of the plurality of nozzles being separated from each other by the first shielding member.

Description

Technical Field

[0001] This disclosure relates to an electrostatic inkjet head and printing apparatus that ejects charged liquid from a nozzle via electrostatic attraction (EHD: Electro Hydro Dynamic). Background Technology

[0002] In recent years, the development of manufacturing technologies for printed electronics formed on substrates using printing technology has been underway. Among the printing technologies used in the manufacture of printed electronics, electrostatic inkjet printing, which applies ink to the printed medium by imparting a charge to the ink and electrostatically attracting it from electrodes on the printed medium side, is useful.

[0003] In electrostatic inkjet printing, to improve ejection stability, it is important to suppress interference of the electric field caused by the potential difference between the electrodes disposed in adjacent nozzles. For example, Patent Document 1 discloses a technique for preventing electric field interference by using a conductive member disposed between the ejection electrodes of adjacent nozzles.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2002-166555 Summary of the Invention

[0005] In Patent Document 1, the conductive component is only provided in a portion between the ink ejection outlets of adjacent nozzles. Therefore, in the areas where the conductive component is not provided, interference of the electric field between the electrodes of adjacent nozzles may occur.

[0006] The purpose of this disclosure is to provide an electrostatic inkjet head capable of reducing the influence of an electric field generated by an electrode disposed on a nozzle, and a printing apparatus having the electrostatic inkjet head.

[0007] One aspect of this disclosure discloses an electrostatic inkjet head that ejects liquid from a nozzle by electrostatic attraction, comprising: a main body having a plurality of nozzles arranged thereon; a first electrode for applying a pulse voltage to charge the liquid; and a first shielding member disposed inside the main body along the ejection direction of the liquid, wherein adjacent nozzles among the plurality of nozzles have opposite ends in the ejection direction, the opposite ends being located closer to the first electrode on the opposite side, and the first shielding member shielding the electric field generated by the first electrode.

[0008] One aspect of the printing apparatus disclosed herein includes: the aforementioned electrostatic inkjet head; a moving device for moving a workpiece relative to the electrostatic inkjet head; a counter electrode disposed on the moving device; and a control device for controlling the electrostatic inkjet apparatus and the moving device.

[0009] According to the present invention, the influence of the electric field generated by the electrode provided on the nozzle can be reduced. Attached Figure Description

[0010] Figure 1 This is a diagram illustrating an example of the structure of a printing apparatus according to an embodiment of the present disclosure.

[0011] Figure 2 This is a schematic diagram illustrating the structure of a printing apparatus including an electrostatic inkjet head of the first structural example.

[0012] Figure 3 This is a schematic diagram illustrating the structure of a printing apparatus including an electrostatic inkjet head of the second structural example.

[0013] Figure 4 This is a diagram showing the end face of the electrostatic inkjet printer body viewed from the front side of the ejection direction.

[0014] Figure 5A This is a diagram illustrating an example where the second shielding member has a grid shape.

[0015] Figure 5B This is a diagram illustrating an example where the second shielding member has a grid shape.

[0016] Figure 5C This is a diagram illustrating an example where the second shielding member has a grid shape.

[0017] Figure 5D This is a diagram illustrating an example where the second shielding member has a grid shape.

[0018] Figure 6 It is a diagram used to illustrate the charged voltage and ejection voltage supplied to the charged electrode and ejection electrode corresponding to two adjacent nozzles, respectively.

[0019] Figure 7 It is a diagram used to illustrate in more detail the positional relationship between the nozzle, the charged electrode, the ejection electrode, the first shielding member, and the second shielding member.

[0020] Figure 8 This is a diagram illustrating a modified example of the first shielding member of this disclosure. Detailed Implementation

[0021] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, sometimes necessary detailed descriptions are omitted, such as detailed descriptions of well-known matters or repeated descriptions of substantially the same structures.

[0022] [Printing apparatus 100] <Overall Structure> Figure 1 This is a diagram illustrating an example of the structure of a printing apparatus 100 according to an embodiment of the present disclosure. Figure 1 This is a top view of the printing apparatus 100. Furthermore, in this embodiment, the mounting surface of the printing apparatus 100 is defined as the XY plane, and the direction perpendicular to the mounting surface is defined as the Z-axis direction for explanation. Figure 1 In this design, for example, the X and Y axes are contained in a horizontal plane, and the Z axis is set along the vertical direction. However, in this disclosure, the liquid ejection device does not necessarily need to be set in a horizontal plane, and a slight tilt is also permissible.

[0023] The printing apparatus 100 includes an electrostatic inkjet head 10 or 20, a liquid tank 30, a stage 40, a control unit 50, a liquid supply path 60, and a liquid recovery path 70. Figure 1 The description of the electrostatic inkjet head 10 (20) shows that the printing apparatus 100 includes either the electrostatic inkjet head 10 of the first structural example described below or the electrostatic inkjet head 20 of the second structural example described later.

[0024] In this specification, the positive side in the Z-axis direction corresponds to the upper side when viewed from the printing device 100, and the negative side in the X-axis direction corresponds to the lower side when viewed from the printing device 100. For example... Figure 1 As shown, the printing apparatus 100, including an electrostatic inkjet head 10 or 20, is disposed on a horizontal plane, and the electrostatic inkjet head 10 or 20 ejects liquid downwards (see below). Figure 2 That is, in this specification, the upper side corresponds to the positive side in the Z-axis direction and the negative side in the direction of liquid ejection. Furthermore, in this specification, the lower side corresponds to the negative side in the Z-axis direction and the positive side in the direction of liquid ejection.

[0025] The electrostatic inkjet head 10 or 20 sprays ink or other liquid onto the printing medium 300 placed on the stage 40. The liquid tank 30 stores the liquid supplied to the electrostatic inkjet head 10. The stage 40 is a transport unit that moves the electrostatic inkjet head 10 or 20 relative to the printing medium 300, such as a substrate. The control unit 50 controls the operation of the electrostatic inkjet head 10 and the stage 40. The liquid supply path 60 is a path that supplies liquid from the liquid tank 30 to the electrostatic inkjet head 10 or 20. The liquid recovery path 70 is a path that recovers liquid from the electrostatic inkjet head 10 or 20 back to the liquid tank 30.

[0026] <Electrostatic inkjet head> (First structural example) Hereinafter, a first structural example of an electrostatic inkjet head according to an embodiment of the present disclosure will be described. Figure 2 This is a schematic diagram illustrating the structure of a printing apparatus 100 including the electrostatic inkjet head 10 of the first structural example. Figure 2The image shows a cross-section of the electrostatic inkjet head 10 at the location where the nozzles are positioned, a counter electrode 80, and a printing medium 300 held by the counter electrode 80. Furthermore, the counter electrode 80 is positioned at... Figure 1 On the stage 40 shown. Figure 2 A cross-sectional view of a plane (XZ plane) parallel to the ejection direction of the electrostatic inkjet head 10 is shown.

[0027] The electrostatic inkjet head 10 includes a liquid reservoir 11, a liquid reservoir 12, a nozzle 13, a charged electrode 14, a main body 15, a charged voltage waveform generating unit 16, a first shielding member 17, and a second shielding member 18. Furthermore, the charged electrode 14 is an example of the first electrode disclosed herein.

[0028] Reservoir 11 stores from Figure 1 The liquid supplied by the liquid tank 330 shown. A liquid supply flow path 60 and a liquid recovery flow path 70 are connected to the liquid reservoir 11. Multiple nozzles 13 are connected to the liquid reservoir 11 via a liquid storage chamber 12, which is a separate flow path.

[0029] Nozzle 13 is a nozzle for ejecting liquid. Furthermore, the liquid used in the printing apparatus 100 of this embodiment may be, for example, silver nano-ink, ink containing metal particles other than silver, ink composed of conductive solvents, ink composed of insulating solvents, UV ink, and solder paste. The viscosity of the liquid can be between 3 mPa·s and 20,000 mPa·s.

[0030] The nozzle 13 has an outlet 13A at the end on the positive side (i.e., the lower side) of the liquid ejection direction, and the inner diameter (nozzle diameter) of the outlet 13A can be formed to be, for example, 0.5 μm or more and 200 μm or less.

[0031] The nozzle 13 is formed inside a plurality of recesses 15D provided in the main body portion 15. More specifically, as Figure 2 As shown, the nozzle 13 is disposed at the center of the recess 15D, and a groove 15G is formed around the nozzle 13. The groove 15G suppresses the area of ​​the region surrounding the nozzle outlet 13A at the lower end of the nozzle 13, thereby suppressing the diffusion of liquid on the lower end face of the nozzle 13 due to the surface tension of the liquid.

[0032] Thus, the nozzle 13 is formed inside the recess 15D in such a way that it protrudes downward from the bottom side of the upper side in the ejection direction of the recess 15D.

[0033] With such a nozzle 13 shape, the nozzle outlet 13A, located at the lower end of the nozzle 13, is positioned above the lower end face 15S of the main body 15 in the ejection direction.

[0034] In addition, such as Figure 2As shown, multiple nozzles 13 are arranged side-by-side along a specific orientation. Figure 2 In the example shown, the multiple nozzles 13 are arranged in the X-axis direction.

[0035] The charged electrode 14 is an electrode that applies a pulse voltage to the liquid inside the nozzle 13 for ejection from the nozzle. The charged electrode 14 is disposed inside the nozzle 13 and near the ejection outlet 13A. The charged electrode 14 is disposed for each nozzle 13. The lower end of the charged electrode 14 is located at the lower end of the nozzle 13, i.e., the ejection outlet 13A, in the ejection direction. The upper end of the charged electrode 14 is located at a predetermined distance above the ejection outlet 13A in the ejection direction. The length of the charged electrode 14 along the ejection direction can be appropriately set based on the magnitude of the pulse voltage applied to the liquid inside the nozzle 13, for example, 30 μm. The pulse voltage applied to the liquid by the charged electrode 14 is supplied by the charged voltage waveform generation unit 16.

[0036] Furthermore, in this specification, the liquid near the nozzle 13A includes the liquid present in the area inside the nozzle 13 near the nozzle 13A, and the liquid forming a curved liquid surface that bulges from the nozzle 13A toward the lower side (opposite electrode 80 side) of the nozzle 13.

[0037] The main body 15 is a component with other structures on which the electrostatic inkjet head 10 is provided. As described above, a plurality of recesses 15D are formed in the main body 15 along the arrangement direction of the nozzles 13. The main body 15 is formed of insulating materials such as glass, ceramic, or resin.

[0038] The charged voltage waveform generation unit 16, via the control unit 50 (see reference) Figure 1 The control unit 50 independently applies pulse voltages to the charged electrodes 14 disposed on the multiple nozzles 13. The charged voltage waveform generation unit 16 and the control unit 50 are interconnected, for example, via a flexible cable.

[0039] The first shielding member 17, for example, is grounded and is a plate-shaped member that shields the electric field generated by the charged electrode 14. The first shielding member 17 is arranged approximately perpendicular to the arrangement direction (X-axis direction) of the nozzles 13 inside the main body 15. In other words, the surfaces of the plate-shaped first shielding member 17 extend in both the ejection direction and the depth direction perpendicular to both the ejection direction and the arrangement direction. The depth direction refers to... Figure 2 The Y-axis direction is shown.

[0040] like Figure 2 As shown, the opposite sides of the two ends of the first shielding member 17 in the ejection direction (i.e., Figure 2The upper end 17A of the first shielding member 17 is located above the charged electrode 14. Additionally, the positive side of the two ends of the first shielding member 17 in the ejection direction (i.e., the side in the ejection direction) is... Figure 2 The lower end 17B of the first shielding member 17 is located at the lower end face 15S of the main body 15 in the ejection direction. That is, the lower end 17B of the first shielding member 17 is located at a position lower than the charged electrode 14.

[0041] Furthermore, the inner end of the first shielding member 17, which is formed in a plate shape, is located further inward than the inner end of the charged electrode 14 in the depth direction. The near-front end of the first shielding member 17 in the depth direction is located closer to the front than the near-front end of the charged electrode 14. Additionally, the inner side in the depth direction corresponds to... Figure 2 The inner side of the middle, the near-anterior side in the depth direction corresponds to Figure 2 The first shielding member 17 is positioned in a larger area than the charged electrode 14 in the depth direction perpendicular to the arrangement direction of the plurality of nozzles 13 and the ejection direction.

[0042] like Figure 2 As shown, a plurality of first shielding members 17 are formed between adjacent nozzles 13. Additionally, as... Figure 2 As shown, the first shielding member 17 is also positioned outward from the nozzles 13 at both ends in the arrangement direction of the plurality of nozzles 13. The first shielding member 17 positioned outward from the nozzles 13 at both ends in the arrangement direction of the nozzles 13 can be positioned symmetrically with respect to the first shielding member 17 positioned inward from the nozzles 13 at both ends. Furthermore, in the first structural example, "outward from the nozzles 13 at both ends in the arrangement direction" means the side of the nozzles 13 at both ends that is further away from the center of the electrostatic inkjet head 10 in the arrangement direction. Conversely, "inward from the nozzles 13 at both ends in the arrangement direction" means the side of the nozzles 13 at both ends that is closer to the center of the electrostatic inkjet head 10 in the arrangement direction.

[0043] Thus, the first shielding member 17 is configured to cover an area larger than the area where the charged electrode 14 is disposed in both the ejection direction and the depth direction. Therefore, the first shielding member 17 can effectively shield the electric field generated by the charged electrode 14. By distributing the first shielding member 17 between adjacent nozzles 13, it is possible to effectively suppress the situation where the charged electrode 14 formed on one nozzle 13 affects the liquid ejected from adjacent nozzles 13. Therefore, it is possible to effectively suppress the situation where the electric field generated by the charged electrode 14 formed on one nozzle 13 attracts liquid ejected from other nozzles 13, preventing the liquid from landing at the desired location.

[0044] Here, in the electrostatic inkjet head 10 of the first structural example, by positioning the upper end 17A of the first shielding member 17 above the charged electrode 14, the component of the electric field generated by the charged electrode 14 that is positioned above the charged electrode 14 can be shielded particularly effectively.

[0045] Furthermore, in the electrostatic inkjet head 10 of the first structural example, by positioning the lower end 17B of the first shielding member 17 at a position lower than the charged electrode 14, the component of the electric field generated by the charged electrode 14 that is generated at a position lower than the charged electrode 14 can be shielded particularly effectively.

[0046] The second shielding member 18 is grounded in the same manner as the first shielding member 17, and is a member that shields the electric field generated by the charged electrode 14. The second shielding member 18 is formed along the lower end face 15S of the main body 15, except for the position of the nozzle 13 outlet 13A. In addition, the second shielding member 18 can also be electrically connected to the first shielding member 17.

[0047] The second shielding member 18 is formed on the entire surface of the end face 15S on the lower side of the main body 15, excluding the recess 15D. Alternatively, the second shielding member 18 may be uniformly formed on the entire surface of the end face 15S. Or, the second shielding member 18 may have a grid shape, with a portion of the end face 15S protruding between the grid shapes. The grid shape of the second shielding member 18 may include, for example, polygons such as triangles, quadrilaterals, hexagons, or circles. Furthermore, the coefficients of linear expansion of the main body 15, made of ceramic or glass, and the second shielding member 18, made of metal, are significantly different, resulting in differences in the degree of expansion under temperature changes. Due to this difference in expansion, a force is applied to the second shielding member 18, and the second shielding member 18 may sometimes peel off from the end face 15S of the main body 15. From the viewpoint of preventing this, the grid shape of the second shielding member 18 preferably does not have an arrangement direction that is parallel to the plurality of nozzles 13 (e.g., Figure 2 The straight section that is parallel to the X-axis direction and longer than the distance between adjacent nozzles 13.

[0048] To explain in more detail: Even when the grid shape includes straight sections that are parallel to the arrangement direction of the multiple nozzles 13 as part of it, these straight sections are connected to the parts of the grid shape that are not parallel to the arrangement direction. Moreover, the length of these straight sections is formed to be shorter than the distance between adjacent nozzles 13. As a result, it is possible to suppress the situation where the electric field generated by the charged electrode 14 provided on one nozzle 13 is transmitted to the charged electrodes 14 provided on adjacent nozzles 13 via the straight sections of the grid shape.

[0049] Furthermore, this disclosure is not limited thereto; for example, the grid shape may also have a shape that is tilted at a predetermined angle relative to the arrangement direction of the plurality of nozzles 13.

[0050] The area occupied by the second shielding member 18 with a grid shape in the end face 15S can be, for example, less than 50%, more preferably less than 10% of the total area of ​​the end face 15S. In this way, by reducing the area occupied by the second shielding member 18 in the end face 15S, it is possible to suppress the electric field generated in the charged electrode 14 from concentrating towards the second shielding member 18, thereby preventing the liquid ejection from being blocked by the second shielding member 18.

[0051] In this way, by forming the second shielding member 18 in such a way as to cover the end face 15S on the lower side of the main body 15, it is possible to shield the component of the electric field generated by the charged electrode 14 that is generated at a position lower than the charged electrode 14 in a particularly effective manner.

[0052] An electrostatic inkjet head 10 with this structure is formed, for example, as follows. First, insulating materials such as glass, ceramics, and resin are prepared. These materials are then processed using methods such as drilling, etching, electrical discharge machining, sandblasting, laser-induced etching, dry etching, opening of photosensitive glass, and injection molding to form the reservoir 11, reservoir 12, nozzle 13, and body 15. Alternatively, the reservoir 11, reservoir 12, nozzle 13, and body 15 can be formed by stacking plates with a thickness of tens of μm, or by forming films of glass, resin, ceramics, etc., using methods such as plasma CVD (Chemical Vapor Deposition) or vapor deposition. When each structure is formed by stacking plates, the stacked plates can be joined together by bonding methods such as adhesives or direct bonding.

[0053] Next, the charged electrode 14, the first shielding member 17, and the second shielding member 18 are formed using methods such as plating, evaporation, sputtering, CVD, and ALD (Atomic Layer Deposition). Regarding the second shielding member 18, it can be formed, for example, after the holes are formed in the main body 15, using the methods described above. It can also be formed with the charged electrodes 14 of multiple nozzles 13 connected, and then patterned using etching or other methods to divide it into individual nozzles. When the reservoir 11, reservoir 12, nozzle 13, and main body 15 are fabricated by stacking plates, the charged electrode 14, the first shielding member 17, and the second shielding member 18 can be formed in the form of plates, or after stacking. When the reservoir 11, reservoir 12, nozzle 13, and main body 15 are formed by film deposition, the charged electrode 14, the first shielding member 17, and the second shielding member 18 can be appropriately formed according to the thickness of the film.

[0054] An insulating film such as SiO2 can also be formed on the surfaces of the charged electrode 14, the first shielding member 17, and the second shielding member 18. The insulating film can be formed, for example, by plasma CVD, evaporation, sputtering, or by sealing with an adhesive.

[0055] like Figure 2 As shown, a counter electrode 80 capable of holding the printing medium 300 is provided at a position opposite to the nozzle exit 13A of each nozzle 13 of the electrostatic inkjet head 10. A constant voltage is applied to the counter electrode 80 to a degree that does not eject liquid from the nozzle 13. Alternatively, the counter electrode 80 may be grounded. Alternatively, a pulse voltage with the opposite polarity to the pulse voltage applied to the charged electrode 14 may be applied to the counter electrode 80 at the timing of liquid ejection.

[0056] The printing medium 300 is held on the counter electrode 80 disposed on the stage 40. The printing medium 300 can be, for example, a glass, ceramic, glass epoxy board, polyimide, resin substrate, or metal substrate. The distance between the counter electrode 80 and the nozzle exit 13A is adjusted so that the distance between the printing medium 300 and the nozzle exit 13A is approximately 10 μm to 500 μm.

[0057] The stage 40 and the control unit 50 are interconnected, for example, via a flexible cable. This allows the control unit 50 to move the electrostatic inkjet head 10 and the stage 40 relative to each other. The control unit 50 obtains position information related to the positions of the nozzles 13 of the electrostatic inkjet head 10 and the position of the stage 40 (and consequently, the position on the printing medium 300) from a predetermined position sensor. Based on this position information, the control unit 50 moves the electrostatic inkjet head 10 and the stage 40 relative to each other so that any printing position on the printing medium 300 coincides with the position of a specific nozzle 13 of the electrostatic inkjet head 10 in the XY plane. At the timing when the position of any printing position on the printing medium 300 coincides with the position of a specific nozzle 13 of the electrostatic inkjet head 10 in the XY plane (more preferably, a timing that takes into account the time it takes for the liquid ejected from the nozzle 13 to reach the printing position), the control unit 50 supplies a pulse voltage to the charged electrode 14 via the charged voltage waveform generation unit 16 to cause the liquid to be ejected from the nozzle 13. Thus, liquid can be applied to the desired position on the printing medium 300, and by repeating this process, the desired printing can be performed on the printing medium 300.

[0058] As explained above, in the electrostatic inkjet head 10 according to the first structural example, a first shielding member 17 is disposed inside the main body 15 along the liquid ejection direction. The negative side, i.e., the upper side, of the first shielding member 17 in the ejection direction is located above the charged electrode 14. Furthermore, the positive side, i.e., the lower side, of the first shielding member 17 in the ejection direction is located below the lower side of the charged electrode 14. Moreover, a plurality of first shielding members 17 are formed between adjacent nozzles 13.

[0059] Thus, the first shielding member 17 is formed to cover a region larger than the region where the charged electrode 14 is disposed in the ejection direction. Therefore, the first shielding member 17 can effectively shield the electric field generated by the charged electrode 14. By disposing the first shielding member 17 between adjacent nozzles 13, it is possible to effectively suppress the influence of the charged electrode 14 formed on one nozzle 13 on the liquid ejected from the adjacent nozzle 13.

[0060] Here, in the electrostatic inkjet head 10 of the first structural example, by positioning the upper end 17A of the first shielding member 17 above the charged electrode 14, the component of the electric field generated by the charged electrode 14 that is positioned above the charged electrode 14 can be shielded particularly effectively.

[0061] Furthermore, in the electrostatic inkjet head 10 of the first structural example, by positioning the lower end 17B of the first shielding member 17 at a position lower than the charged electrode 14, the component of the electric field generated by the charged electrode 14 that is generated at a position lower than the charged electrode 14 can be shielded particularly effectively.

[0062] Furthermore, in the electrostatic inkjet head 10 of the first structural example, by forming the second shielding member 18 in such a way that it covers the end face 15S on the lower side of the main body 15, it is possible to more effectively shield the component of the electric field generated by the charged electrode 14 that is generated at a position lower than the charged electrode 14.

[0063] Therefore, with such a structure, it is possible to effectively suppress the situation where the electric field generated by the charged electrode 14 formed in a certain nozzle 13 attracts the liquid ejected from other nozzles 13 and the liquid does not fall to the desired position.

[0064] (Second structural example) Next, a second structural example of the electrostatic inkjet head according to the embodiments of this disclosure will be described. Figure 3 This is a schematic diagram illustrating the structure of a printing apparatus 100 including the electrostatic inkjet head 20 of the second structural example. Figure 3 A cross-sectional view of a plane (XZ plane) parallel to the ejection direction of the electrostatic inkjet head 20 is shown.

[0065] like Figure 3 As shown, the electrostatic inkjet head 20 includes a reservoir 21, a reservoir chamber 22, a nozzle 23, a charged electrode 24, an ejection electrode 25, a main body 26, a charged voltage waveform generation unit 27, an ejection voltage waveform generation unit 28, a first shielding member 29, and a second shielding member 210. The charged electrode 24 is an example of the first electrode of this disclosure. The ejection electrode 25 is an example of the second electrode of this disclosure.

[0066] Reservoir 21 stores from Figure 1 The liquid supplied by the liquid tank 30 shown. A liquid supply flow path 60 and a liquid recovery flow path 70 are connected to the liquid reservoir 21. Multiple nozzles 23 are connected to the liquid reservoir 21 via a liquid storage chamber 22, which is a separate flow path.

[0067] Nozzle 23 is a nozzle that ejects liquid. Nozzle 23 has an outlet 23A at its end on the positive side (i.e., the lower side) in the direction of liquid ejection, and the inner diameter (nozzle diameter) of the outlet 23A can be formed to be, for example, 0.5 μm or more and 200 μm or less.

[0068] The nozzle 23 is formed inside a plurality of recesses 26D provided in the main body 26. More specifically, as Figure 3 As shown, the nozzle 23 is disposed at the center of the recess 26D, and a groove 26G is formed around the nozzle 23. The groove 26G reduces the area of ​​the region surrounding the nozzle outlet 23A at the lower end of the nozzle 23, thereby suppressing the diffusion of liquid on the lower end face of the nozzle 23 due to the surface tension of the liquid.

[0069] Thus, the nozzle 23 is formed inside the recess 26D in such a way that it protrudes downward from the bottom side of the upper side in the ejection direction of the recess 26D.

[0070] With such a nozzle 23 shape, the nozzle outlet 23A located at the lower end of the nozzle 23 is positioned above the lower end face 26S of the main body 26 in the ejection direction.

[0071] In addition, such as Figure 3 As shown, multiple nozzles 23 are arranged along a specific orientation. Figure 3 In the example shown, the multiple nozzles 23 are arranged in the X-axis direction.

[0072] The charged electrode 24 is an electrode that applies a pulse voltage of a size that is not large enough to cause the liquid inside the nozzle 23 to spray out. A pulse voltage with reversed polarity for each pulse can also be supplied to the charged electrode 24. The charged electrode 24 is disposed inside the nozzle 23 and near the outlet 23A. The charged electrode 24 is disposed for each nozzle 23. The lower end of the charged electrode 24 is located at the lower end of the nozzle 23, i.e., the outlet 23A, in the spraying direction. The upper end of the charged electrode 24 is located at a predetermined distance above the outlet 23A in the spraying direction. The length of the charged electrode 24 along the spraying direction can be appropriately set based on the magnitude of the pulse voltage applied to the liquid inside the nozzle 23, for example, 30 μm. The pulse voltage applied to the liquid by the charged electrode 24 is supplied by the charged voltage waveform generation unit 27.

[0073] Furthermore, in this specification, the liquid near the nozzle 23A includes the liquid present inside the nozzle 23 in the region near the nozzle 23A, and the liquid forming a curved liquid surface that bulges from the nozzle 23A toward the lower side (opposite electrode 80 side) of the nozzle 23.

[0074] The ejection electrode 25 is an electrode that applies a pulse voltage to the liquid inside the nozzle 23 for ejection at arbitrary timings. Alternatively, a pulse voltage with reversed polarity for each pulse can be supplied to the ejection electrode 25. The waveform of the pulse voltage supplied to the ejection electrode 25 is synchronized with the waveform of the pulse voltage supplied to the charged electrode 24.

[0075] The ejection electrode 25 is disposed on the inner surface of the recess 26D of the main body 26 and is positioned lower than the ejection outlet 23A of the nozzle 23 in the ejection direction. The ejection electrodes 25 are disposed in a plurality of recesses 26D. Liquid near the ejection outlet 23A, which is charged by a pulse voltage supplied to the charged electrode 24, is attracted by the electrostatic force generated by the electric field produced by the pulse voltage supplied to the ejection electrode 25, thereby ejecting the liquid from the nozzle 23 in the ejection direction. This ejection method is, for example, called an electrostatic attraction method.

[0076] The main body 26 is a plate-shaped component with other structures provided for the electrostatic inkjet head 20. As described above, a plurality of recesses 26D are formed in the main body 26 along the arrangement direction of the nozzles 23. The main body 26 is formed of insulating materials such as glass, ceramic, or resin.

[0077] The charged voltage waveform generation unit 27, via the control unit 50 (see reference) Figure 1The control unit 50 controls the application of pulse voltages to the charged electrodes 24 disposed on the plurality of nozzles 23. Furthermore, the ejection voltage waveform generation unit 28, under the control of the control unit 50, independently applies pulse voltages to the ejection electrodes 25 disposed inside the plurality of recesses 26D. The charged voltage waveform generation unit 27 and the ejection voltage waveform generation unit 28 are interconnected with the control unit 50, for example, via flexible cables.

[0078] The first shielding member 29, for example, is grounded and is a plate-shaped member that shields the electric field generated by the charged electrode 24 and the ejection electrode 25. The first shielding member 29 is arranged approximately perpendicular to the arrangement direction (X-axis direction) of the nozzles 23 inside the main body 26. In other words, the surfaces of the plate-shaped first shielding member 29 extend in both the ejection direction and the depth direction perpendicular to both the ejection direction and the arrangement direction. The depth direction refers to... Figure 3 The Y-axis direction is shown.

[0079] like Figure 3 As shown, the opposite sides of the two ends of the first shielding member 29 in the ejection direction (i.e., Figure 3 The upper end 29A of the first shielding member 29 is located above the charged electrode 24. Additionally, the positive side of the two ends of the first shielding member 29 in the ejection direction (i.e., the side in the ejection direction) is... Figure 3 The lower end 29B of the first shielding member 29 is located at the lower end face 26S of the main body 26 in the ejection direction. That is, the lower end 29B of the first shielding member 29 is located at a position lower than the ejection electrode 25.

[0080] Furthermore, the inner end of the first shielding member 29, which is formed in a plate shape, is located further inward than the inner ends of the charged electrode 24 and the ejection electrode 25 in the depth direction. The near-front end of the first shielding member 29 in the depth direction is located closer to the front than the near-front ends of the charged electrode 24 and the ejection electrode 25. Additionally, the inner end in the depth direction corresponds to... Figure 2 The inner side of the middle, the near-anterior side in the depth direction corresponds to Figure 2 The first shielding member 17 is positioned in a depth direction perpendicular to the arrangement direction of the plurality of nozzles 23 and the ejection direction, and is larger than the charged electrode 24 and the ejection electrode 25.

[0081] Moreover, such as Figure 3 As shown, a plurality of first shielding members 29 are formed between adjacent nozzles 23. Additionally, as... Figure 3As shown, the first shielding member 29 is also positioned outward from the nozzles 23 at both ends in the arrangement direction of the plurality of nozzles 23. The first shielding member 29 positioned outward from the nozzles 23 at both ends in the arrangement direction of the nozzles 23 can be positioned symmetrically with respect to the first shielding member 29 one inward from each of the nozzles 23 at both ends. Furthermore, in the second structural example, "outward from the nozzles 23 at both ends in the arrangement direction" means the side of the nozzles 23 at both ends that is further away from the center of the electrostatic inkjet head 20 in the arrangement direction. Conversely, "inward from the nozzles 23 at both ends in the arrangement direction" means the side of the nozzles 23 at both ends that is closer to the center of the electrostatic inkjet head 20 in the arrangement direction.

[0082] Thus, the first shielding member 29 is formed to cover a region larger than the region where the charged electrode 24 and the ejection electrode 25 are disposed in the ejection direction. Therefore, the first shielding member 29 can effectively shield the electric field generated by the charged electrode 24 and the ejection electrode 25. By distributing the first shielding member 29 between adjacent nozzles 23, the influence of the charged electrode 24 and the ejection electrode 25 corresponding to one nozzle 23 on the liquid ejected from adjacent nozzles 23 can be effectively suppressed. Therefore, the situation where the electric field generated by the charged electrode 24 and the ejection electrode 25 corresponding to a certain nozzle 23 attracts liquid ejected from other nozzles 23 and the liquid does not land at the desired position can be effectively suppressed.

[0083] Here, in the electrostatic inkjet head 20 of the second structural example, by positioning the upper end 29A of the first shielding member 29 above the charged electrode 24, the component of the electric field generated by the charged electrode 24 and the ejection electrode 25 that is positioned above the charged electrode 24 can be shielded particularly effectively.

[0084] Furthermore, in the electrostatic inkjet head 20 of the second structural example, by positioning the lower end 29B of the first shielding member 29 at a position lower than the ejection electrode 25, the component of the electric field generated by the charged electrode 24 and the ejection electrode 25 that is generated at a position lower than the ejection electrode 25 can be shielded particularly effectively.

[0085] The second shielding member 210 is grounded in the same manner as the first shielding member 29, and is a member that shields the electric field generated by the charged electrode 24 and the ejection electrode 25. The second shielding member 210 is formed such that the recess 26D is removed along the end face 26S on the lower side of the main body portion 26. Furthermore, the second shielding member 210 can also be electrically connected to the first shielding member 29.

[0086] The second shielding member 210 is formed on the entire surface of the end face 26S on the lower side of the main body 26, excluding the recess 26D. Alternatively, the second shielding member 210 may be uniformly formed on the entire surface of the end face 26S. Or, the second shielding member 210 may have a grid shape, with a portion of the end face 26S protruding between the grid shapes. The grid shape of the second shielding member 210 may include, for example, polygons such as triangles, quadrilaterals, hexagons, or circles. Furthermore, similar to the first structural example, the coefficients of linear expansion of the main body 26, made of ceramic or glass, and the metal second shielding member 210 are significantly different, resulting in a difference in the degree of expansion under temperature changes. Due to this difference in expansion, a force is applied to the second shielding member 219, and the second shielding member 210 may sometimes peel off from the end face 26S of the main body 26. From the viewpoint of preventing this, the grid shape of the second shielding member 210 preferably does not have an arrangement direction parallel to the nozzle 23 (i.e., Figure 3 The straight section (shown in the X-axis direction) is parallel to and longer than the distance between adjacent nozzles 23 in the arrangement direction.

[0087] To explain in more detail: Even when the grid shape includes straight sections parallel to the arrangement direction of the multiple nozzles 23 as part of it, these straight sections are connected to the parts of the grid shape that are not parallel to the arrangement direction. Moreover, the length of these straight sections is formed to be shorter than the distance between adjacent nozzles 23. As a result, it is possible to suppress the electric field generated by the charged electrode 24 and ejection electrode 25 corresponding to a certain nozzle 23 from being transmitted to the charged electrode 24 and ejection electrode 25 corresponding to adjacent nozzles 23 via the straight sections of the grid shape.

[0088] Furthermore, this disclosure is not limited thereto; for example, the grid shape may also have a shape that is tilted at a predetermined angle relative to the arrangement direction of the plurality of nozzles 13.

[0089] The area occupied by the second shielding member 210, which has a grid shape, in the end face 26S can be, for example, less than 50%, more preferably less than 10%, relative to the total area of ​​the end face 26S. In this way, by reducing the area occupied by the second shielding member 210 in the end face 26S, it is possible to suppress the generation of an electric field towards the second shielding member 210 due to the voltage supplied to the charged electrode 24 and the ejection electrode 25, thereby preventing the ejection of liquid from being obstructed by the second shielding member 210.

[0090] Figure 4 This is a diagram showing the end face 26S of the main body 26 of the electrostatic inkjet head 20, viewed from the front side (bottom side) of the ejection direction of the main body 26. Figure 4 The diagram shows the positional relationship of multiple nozzles 23, charged electrodes 24 formed inside the nozzles 23, recesses 26D, and grooves 26G. Additionally, in... Figure 4 In the diagram, dashed lines indicate the positions of the ejection electrode 25 and the first shielding member 29 formed inside the main body 26. Additionally, in... Figure 4 In the diagram, the case where a second shielding member 210 is provided is indicated by a shaded line. For example... Figure 4 As shown, the first shielding member 29 is disposed in a larger area than the charged electrode 24 and the ejection electrode 25 in the depth direction (Y-axis direction).

[0091] Figures 5A-5D This is a diagram illustrating an example of the second shielding member 210 having a grid shape. Figure 5A The second shielding member 210 is shown to have a grid shape containing quadrilaterals. Figure 5B The second shielding member 210 is shown to have a grid shape containing triangles. Figure 5C A portion of the second shielding member 210 is shown in a case where it has a grid shape containing hexagons. Figure 5D A portion of the second shielding member 210 is shown in a case where it has a grid shape containing a circle.

[0092] like Figures 5A-5D As shown, when the second shielding member 210 has a grid shape, from the viewpoint of preventing peeling, it is preferable not to have an arrangement direction that is side by side with the plurality of nozzles 23. Figures 5A-5D A continuous straight line parallel to the X-axis direction.

[0093] return Figure 3 The charged voltage waveform generation unit 27 supplies pulse voltage to the charged electrode 24 based on the control of the control unit 50. The pulse voltage supplied to the charged electrode 24 by the charged voltage waveform generation unit 27 will be referred to as the charged voltage below. The charged voltage waveform generation unit 27 can also reverse the polarity for each pulse of the charged voltage. The charged voltage waveform generation unit 27 can also individually change the pulse width, pulse generation timing, and the presence or absence of polarity reversal for each charged electrode 24 corresponding to the multiple nozzles 23. The charged voltage is, for example, -5kV or higher and 5kV or lower.

[0094] The ejection voltage waveform generation unit 28 supplies pulse voltage to the ejection electrode 25 based on the control of the control unit 50. The pulse voltage supplied by the ejection voltage waveform generation unit 28 to the ejection electrode 25 will be referred to as the ejection voltage. The ejection voltage waveform generation unit 28 can also reverse the polarity for each pulse of the ejection voltage. The ejection voltage waveform generation unit 28 can also individually change the pulse width, pulse generation timing, and the presence or absence of polarity reversal for each ejection electrode 25 corresponding to the multiple nozzles 23. The ejection voltage is, for example, -4kV or higher and 4kV or lower.

[0095] Figure 6This is a diagram illustrating the charged voltage and ejection voltage supplied to the charged electrodes 24_1, 24_2 and the ejection electrodes 25_1, 25_2 corresponding to the two adjacent nozzles 23_1, 23_2, respectively.

[0096] exist Figure 6 In this process, pulsed voltages are supplied to the charged electrode 24_1 corresponding to nozzle 23_1 and the charged electrode 24_2 corresponding to nozzle 23_2, respectively. Additionally, in Figure 6 In this process, pulsed ejection voltages are supplied to the ejection electrode 25_1 corresponding to nozzle 23_1 and the ejection electrode 25_2 corresponding to nozzle 23_2, respectively.

[0097] The voltage should be set appropriately to prevent liquid from being ejected from nozzles 23_1 and 23_2.

[0098] To achieve the desired ejection timing in nozzles 23_1 and 23_2, ejection voltages are supplied to ejection electrodes 25_1 and 25_2, respectively. The ejection voltage is a pulse voltage supplied in phase with a voltage pulse corresponding to the ejection timing, which reverses the polarity and voltage of the pulse.

[0099] When not ejecting liquid, the liquid inside nozzles 23_1 and 23_2 is charged by the voltage supplied to the charged electrodes 24_1 and 24_2. During ejection timing, when an ejection voltage is supplied to the ejection electrodes 25_1 and 25_2, electric fields are generated. The electrostatic force attracted to the ejection electrodes 25_1 and 25_2 by these electric fields acts on the charged liquid inside nozzles 23_1 and 23_2. Figure 3 and Figure 4 As shown, the ejection electrode 25 is positioned on the positive side (i.e. the lower side) of the nozzle 23 in the ejection direction and is arranged in a circle with the nozzle 23 as the center. Therefore, through the electric field generated by the ejection electrode 25, a portion of the liquid in the nozzles 23_1 and 23_2 is pulled apart in the ejection direction and begins to fly away.

[0100] Alternatively, a constant voltage can be supplied to the counter electrode 80, on which the printing medium 300 is placed, such that liquid will not spray out even when a voltage is supplied to the charged electrode 24. Or, the counter electrode 80 can be grounded.

[0101] Here, nozzles 23_1 and 23_2 respectively target the printing medium 300 (refer to...). Figure 1When liquid is ejected from different pixels (e.g., nozzles 23_1 and 23_2), a difference in ejection timing occurs between nozzles 23_1 and 23_2. In this case, a phase difference may occur between the voltage supplied to the charged electrode 24_1 and the voltage supplied to the charged electrode 24_2. Furthermore, when the ejection timing differs between nozzles 23_1 and 23_2, a phase difference may sometimes occur between the ejection voltage supplied to the ejection electrode 25_1 and the ejection voltage supplied to the ejection electrode 25_2. Due to these phase differences, a large potential difference may sometimes occur between adjacent nozzles 23_1 and 23_2. Such a potential difference may cause the liquid droplets ejected from nozzle 23_1 or nozzle 23_2 to not travel in a straight line in the ejection direction.

[0102] However, in the electrostatic inkjet head 20 of the second structural example, such as Figure 3 As shown, the electric field between adjacent nozzles 23 is appropriately shielded by the first shielding member 29 and the second shielding member 210 in the entire region between the charged electrode 24 and the ejection electrode 25, which is located above the charged electrode 24 and below the ejection electrode 25 in the ejection direction. Therefore, even if a large potential difference is generated between adjacent nozzles 23 due to the phase difference between the charged voltages supplied to the charged electrodes 24 corresponding to each nozzle or the ejection voltages supplied to the ejection electrode 25 caused by the difference in ejection timing between adjacent nozzles 23, the situation where liquid ejected from a certain nozzle 23 cannot travel straight in the ejection direction due to electric field interference from adjacent nozzles 23 can be appropriately suppressed.

[0103] In addition, it can also suppress the situation where the liquid (droplets) ejected from the nozzle 23 is attracted by the electric field generated in the ejection electrode 25 before reaching the printing medium 300, thus preventing it from traveling straight in the ejection direction or causing its speed to decrease.

[0104] Figure 7 This diagram illustrates in more detail the positional relationships of the nozzle 23, the charged electrode 24, the ejection electrode 25, the first shielding member 29, and the second shielding member 210. Figure 3 Similarly, Figure 7 This is a sectional view of the XZ plane, and it is about... Figure 3 An enlarged view of a nozzle 23 is shown.

[0105] like Figure 7 As shown, in a certain nozzle 23, the shortest distance D1 between the charged electrode 24 and the ejection electrode 25 is shorter than the shortest distance D2 between the charged electrode 24 and the first shielding member 29. Additionally, as... Figure 7 As shown, the shortest distance D1 between the charged electrode 24 and the ejection electrode 25 is shorter than the shortest distance D3 between the charged electrode 24 and the second shielding member 210.

[0106] By arranging the nozzle 23, charged electrode 24, ejection electrode 25, first shielding member 29, and second shielding member 210 in this positional relationship, the following effect can be achieved: It is possible to suppress the situation where the electric field generated by the ejection voltage supplied to the ejection electrode 25, which causes the liquid near the nozzle outlet 23A to be charged by the voltage supplied to the charged electrode 24, acts more strongly on the first shielding member 29 or the second shielding member 210. Therefore, it is possible to appropriately suppress the adverse effects of the arrangement of the first shielding member 29 or the second shielding member 210 on the liquid ejected from the nozzle 23.

[0107] <Functions and Effects> The function and effects of the electrostatic inkjet head 10 (20) according to the embodiments of the present disclosure will be explained below. In addition, in the following explanation of the function and effects, corresponding structures in the first and second structural examples are described using reference numerals in parentheses. For example, electrostatic inkjet head 10 (20) refers to electrostatic inkjet head 10 or 20, and nozzle 13 (23) refers to nozzle 13 or 23.

[0108] The electrostatic inkjet head 10 (20) of the present disclosure is an electrostatic inkjet head 10 (20) that ejects liquid from the nozzle 13 (23) by electrostatic attraction. It includes: a main body 15 (26) on which the nozzle 13 (23) is formed; a charged electrode 14 (24) (corresponding to the first electrode of the present disclosure) which applies a pulse voltage to charge the liquid; and a first shielding member 17 (29) which is disposed inside the main body 15 (26) along the ejection direction of the liquid and has an end portion 17A (29A) on the opposite side in the ejection direction. The end portion 17A (29A) on the opposite side is located on the opposite side of the charged electrode 14 (24) and shields the electric field generated by the charged electrode 14 (24).

[0109] That is, the first shielding member 17 (29) is formed to cover a larger area in the ejection direction than the area where the charged electrode 14 (24) is disposed. Therefore, the electric field generated by the charged electrode 14 (24) can be effectively shielded by the first shielding member 17 (29). In particular, the first shielding member 17 (29) can effectively suppress the spread of the electric field from the opposite side of the ejection direction compared to the charged electrode 14 (24).

[0110] In addition, according to the embodiment of the present disclosure, the electrostatic inkjet head 10 (20) has a main body 15 (26) having a plurality of nozzles 13 (23), and a first shielding member 17 (29) is formed between the adjacent nozzles 13 (23) in the plurality of nozzles 13 (23).

[0111] With this structure, the electric field generated by the charged electrode 14 (24) corresponding to one nozzle 13 (23) can be effectively suppressed from acting on the liquid in the other nozzle 13 (23) between adjacent nozzles 23. As a result, interference of electric fields between adjacent nozzles 13 (23) can be effectively suppressed, and the situation where the liquid ejected from the nozzle 13 (23) does not travel straight in the ejection direction can be effectively suppressed.

[0112] In addition, according to the embodiment of the present disclosure, the electrostatic inkjet head 20 has a main body 26 having a recess 26D on the positive side of the end face in the ejection direction, the nozzle 23 being disposed inside the recess 26D, and the first shielding member 29 having a positive side end 29A in the ejection direction, the positive side end 29A being located at a position closer to the positive side than the charged electrode 24.

[0113] With this structure, the first shielding member 29 can effectively suppress the spread of the electric field from the positive side of the ejection direction compared to the charged electrode 24.

[0114] In addition, the electrostatic inkjet head 10 (20) according to the embodiments of the present disclosure also includes a second shielding member 18 (210) formed on the end face 15S (26S) along the front side of the main body 15 (26) and shielding the electric field generated by the charged electrode 14 (24).

[0115] With this structure, the second shielding member 18 (210) can effectively suppress the situation where the electric field generated by the charged electrode 14 (24) spreads from the end face 15S (26S) on the front side of the main body 15 (26) and affects other nozzles 13 (23).

[0116] In addition, according to the embodiment of the present disclosure, the electrostatic inkjet head 20 has a main body 26 having a recess 26D on the positive side of the end face in the ejection direction, a nozzle 23 disposed inside the recess 26D, and a second shielding member 210 formed in the portion of the end face 26S other than the recess 26D.

[0117] With this structure, the second shielding member 210 can effectively suppress the electric field generated by the charged electrode 24 from spreading from the end face 26S on the front side of the main body 26 and affecting other nozzles 23.

[0118] In addition, in the electrostatic inkjet head 10 (20) according to the embodiments of the present disclosure, the second shielding member 18 (210) is formed in a mesh shape on the end face 15S (26S).

[0119] With such a structure, the electric field generated by the voltage supplied to the charged electrode 14 (24) and the ejection electrode 25 toward the second shielding member 18 (210) can be reduced, thereby preventing the ejection of liquid from being blocked by the second shielding member 18 (210).

[0120] Furthermore, in the electrostatic inkjet head 20 according to the embodiments of the present disclosure, the nozzle 23 has an outlet 23A provided at the end on the positive side, and the outlet 23A is located on the opposite side of the end face 26S on the positive side of the main body 26 in the ejection direction.

[0121] In this way, the nozzle outlet 23A is located on the opposite side of the end face 26S of the main body 26 in the ejection direction, so that the positive end of the first shielding member 29 in the ejection direction is reliably located on the positive side of the ejection direction, compared to the nozzle outlet 23A. This effectively suppresses the situation where the electric field generated by the charged electrode 24 or the ejection electrode 25 spreads from the positive end face 26S of the main body 26 and affects other nozzles 23.

[0122] In addition, the electrostatic inkjet head 20 according to the embodiments of the present disclosure also includes an ejection electrode 25 (equivalent to the second electrode of the present disclosure) disposed inside the recess 26D and located on the positive side of the charged electrode 24 in the ejection direction, and the first shielding member 29 has a positive end 29A in the ejection direction, which is located on the positive side of the ejection electrode 25.

[0123] With this structure, it is possible to effectively suppress the electric field generated by the ejection electrode 25 from spreading from the end face 26S on the front side of the main body 26 and affecting other nozzles 23.

[0124] Furthermore, in the electrostatic inkjet head 20 according to the embodiments of this disclosure, the shortest distance D1 between the charged electrode 24 and the ejection electrode 25 is shorter than the shortest distance D2 between the charged electrode 24 and the first shielding member 29. Additionally, the shortest distance D1 between the charged electrode 24 and the ejection electrode 25 is shorter than the shortest distance D3 between the charged electrode 24 and the second shielding member 210.

[0125] With this structure, it is possible to suppress the situation where the electric field generated by the ejection voltage supplied to the ejection electrode 25 acts more strongly on the first shielding member 29 or the second shielding member 210 than the liquid near the ejection port 23A, which is charged by the voltage supplied to the charged electrode 24. Furthermore, the straight-line properties of the liquid ejected from the nozzle 23 can be sufficiently ensured.

[0126] <Variation Example> The embodiments of the electrostatic inkjet head and printing apparatus of this disclosure have been described in detail above. The electrostatic inkjet head 10 or 20 and the printing apparatus 100 described in the above embodiments are examples of the electrostatic inkjet head and printing apparatus of this disclosure, and this disclosure is not limited to the content described in the above embodiments. Modifications to the electrostatic inkjet head and printing apparatus of this disclosure may be made, for example, as follows.

[0127] In the above embodiments, the electrostatic inkjet head 10 (20) has been described in such a way that it has a first shielding member 17 (29) and a second shielding member 18 (210). This disclosure is not limited to this, and the electrostatic inkjet head of this disclosure may, for example, only have a first shielding member disposed between the nozzles along the ejection direction. For example, as in the electrostatic inkjet head 20 of the second structural example, if the first shielding member 29 extends in the ejection direction to a position higher than the charged electrode 24 (corresponding to the first electrode of this disclosure) (i.e., the opposite side in the ejection direction) and to a position lower than the ejection electrode 25 (corresponding to the second electrode of this disclosure) (i.e., the positive side in the ejection direction), the electric field generated by the charged electrode 24 and the ejection electrode 25 can be sufficiently shielded by the first shielding member 29.

[0128] In the above-described embodiments, the first shielding member 17 (29) is a plate-shaped member, but this disclosure is not limited thereto. For example, a plurality of rod-shaped members extending along the ejection direction may also be arranged side by side at a predetermined interval along the depth direction as the first shielding member 17 (29).

[0129] Figure 8 This is a diagram illustrating a modified example of the first shielding member of this disclosure. (and) Figure 4 Similarly, Figure 8 The image shows the state of the end face 26S of the main body 26 of the electrostatic inkjet head 20 in the second structural example, viewed from the front side (bottom side) in the ejection direction of the main body 26. Figure 8 In the example shown, multiple rod-shaped components extending along the ejection direction are arranged side by side at predetermined intervals along the depth direction, thereby constituting the second shielding component 210.

[0130] In this variation, by setting the distance between the rod-shaped members to an appropriate distance, it is possible to achieve approximately the same effect as when the first shielding member 29 is composed of plate-shaped members. The specified interval also depends on the nozzle diameter and the distance between nozzles, but for example, it can be 50 μm or less. As a result, compared to the case where the first shielding member 29 is composed of plate-shaped members, the volume occupied by the first shielding member 29 in the space between adjacent nozzles 23 can be reduced. As a result, it is possible to suppress the electric field generated in the charged electrode 24 or the ejection electrode 25 from concentrating towards the first shielding member 29, thereby preventing the ejection of liquid from being obstructed by the first shielding member 29. By equipping the first shielding member 29 with a structure of arranged rod-shaped members, and setting the volume occupied by the first shielding member 29 to about 50% or less of the volume when it is composed of plate-shaped members, this effect can be achieved efficiently.

[0131] Figure 8 A modified example of the first shielding member 29 in the electrostatic inkjet head 20 of the second structural example is shown, but the first shielding member 17 in the electrostatic inkjet head 10 of the first structure can also be constructed by arranging a plurality of rod-shaped members side by side.

[0132] Industrial availability This disclosure is useful for electrostatic inkjet heads that charge and eject liquids.

[0133] Explanation of reference numerals in the attached figures 100 Printing Equipment 10 Electrostatic inkjet heads 11. Liquid reservoir 12 Liquid storage chambers 13 Nozzles 13A nozzle 14 Charged Electrodes 15 Main body 15D recess 15G slot 15S end face 16. Voltage waveform generation unit 17 First shielding component 18 Second shielding component 20 Electrostatic inkjet heads 21. Liquid reservoir 22 Liquid storage chamber 23 Nozzles 23A nozzle 24 Charged Electrodes 25 Ejection Electrode 26 Main body 26D recess 26G slot 26S end face 27. Voltage waveform generation unit 28. Ejection voltage waveform generation unit 29 First shielding component 210 Second shielding component 30 Liquid Tanks 40 Platform 50 Control Department 60 Liquid supply flow path 70 Liquid recovery flow path 80 Opposite Electrode 300 Printing Media

Claims

1. An electrostatic inkjet head that ejects liquid from a nozzle by electrostatic attraction, wherein, have: The main body has a plurality of the aforementioned nozzles arranged thereon; The first electrode is to be charged with a pulsed voltage that energizes the liquid. as well as A first shielding member is disposed inside the main body along the ejection direction of the liquid, and adjacent nozzles among the plurality of nozzles have opposite ends in the ejection direction, the opposite ends being located closer to the opposite side than the first electrode, the first shielding member shielding the electric field generated by the first electrode.

2. The electrostatic inkjet head according to claim 1, wherein, It also has an additional first shielding component. The additional first shielding member is disposed outside the nozzles at both ends in the arrangement direction of the plurality of nozzles, and is symmetrical about the first shielding member that is one inside the nozzles at both ends, with the nozzles at both ends as the center.

3. The electrostatic inkjet head according to claim 1, wherein, The main body has a plurality of recesses on the end face of the front side in the ejection direction. The plurality of nozzles are respectively disposed inside the plurality of recesses. The first shielding member has a positive end in the ejection direction, and the positive end is located closer to the positive side than the first electrode.

4. The electrostatic inkjet head according to claim 3, wherein, The first shielding member is disposed in a larger area than the first electrode in a direction perpendicular to the arrangement direction of the plurality of nozzles and the ejection direction.

5. The electrostatic inkjet head according to claim 1, wherein, The first shielding member is a plate-shaped member.

6. The electrostatic inkjet head according to claim 1, wherein, The first shielding member is constructed by arranging a plurality of rod-shaped members side by side at a predetermined interval.

7. The electrostatic inkjet head according to claim 1, wherein, It also includes a second shielding member, which is formed along the end face of the front side of the main body in the ejection direction, and shields the electric field generated by the first electrode.

8. The electrostatic inkjet head according to claim 7, wherein, The main body has a plurality of recesses on the end face of the front side in the ejection direction. The plurality of nozzles are respectively disposed inside the plurality of recesses. The second shielding member is formed within the end face of the front side, in addition to the plurality of recesses.

9. The electrostatic inkjet head according to claim 8, wherein, The second shielding member is electrically connected to the first shielding member.

10. The electrostatic inkjet head according to claim 7, wherein, The second shielding member is formed in a grid shape on the end face.

11. The electrostatic inkjet head according to claim 10, wherein, The mesh shape includes straight sections parallel to the arrangement direction of the plurality of nozzles. The straight section is connected to the portion of the grid shape that is not parallel to the arrangement direction. The length of the straight section is shorter than the distance between adjacent nozzles.

12. The electrostatic inkjet head according to claim 10, wherein, The grid shape has a shape that is tilted at a predetermined angle relative to the arrangement direction of the plurality of nozzles.

13. The electrostatic inkjet head according to claim 3, wherein, Each of the plurality of nozzles has an outlet disposed at the end of the positive side, and the outlet of each of the plurality of nozzles is located on the opposite side of the end face of the positive side of the main body in the ejection direction.

14. The electrostatic inkjet head according to claim 13, wherein, It also includes a second electrode, which is disposed inside the plurality of recesses and positioned on the positive side of the first electrode in the ejection direction. The first shielding member has a positive end in the ejection direction, and the positive end is located closer to the positive side than the second electrode.

15. The electrostatic inkjet head according to claim 14, wherein, The first shielding member is disposed in a direction perpendicular to the arrangement direction of the plurality of nozzles and the ejection direction, in a range larger than that of the first electrode and the second electrode.

16. The electrostatic inkjet head according to claim 14, wherein, The shortest distance D1 between the first electrode and the second electrode is shorter than the shortest distance D2 between the first electrode and the first shielding member.

17. The electrostatic inkjet head according to claim 14, wherein, The shortest distance D1 between the first electrode and the second electrode is shorter than the shortest distance D3 between the first electrode and the second shielding member. The second shielding member is formed on the end face of the positive side along the ejection direction of the main body and shields the electric field generated by the first electrode.

18. A printing apparatus, wherein, have: The electrostatic inkjet head according to any one of claims 1 to 17; A moving device that causes the printed material to move relative to the electrostatic inkjet head; Opposing electrodes are mounted on the mobile device; as well as A control device that controls the electrostatic inkjet head and the moving device.

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