JPWO2014068708A1 - Droplet discharge head and printing apparatus - Google Patents

Abstract

The present invention relates to a discharge head (20) including a head body (30) in which a nozzle hole (36) for discharging droplets is formed and a cooling mechanism (34) for cooling the head body (20). The nozzle face (38) where the nozzle hole (36) is opened has a water repellent area (52) formed around the opening of the nozzle hole (36) and a hydrophilic area formed so as to surround the water repellent area (52). And the region (50). With this configuration, the temperature rise of the ejection head is suppressed, and drying of the nozzle surface can be prevented. Moreover, it can suppress that the droplet adhering to a nozzle surface falls to a printing medium.

Description

  The present invention relates to a droplet discharge head that discharges droplets onto a print medium, and a printing apparatus that includes the droplet discharge head.

  When the droplet is not ejected for a long time, the nozzle surface of the droplet ejection head is dried, and the viscosity of the ink or the like may be increased. Ink with increased viscosity may not be able to perform stable printing, and it is desirable to prevent drying of the nozzle surface of the droplet discharge head. For this reason, in the droplet discharge head described in the following patent document, the liquid for preventing drying is evaporated on the nozzle surface and the periphery of the nozzle surface is humidified.

JP 2010-69635 A

  According to the above patent document, it is possible to prevent the droplet discharge head from being dried by humidification around the nozzle surface. However, there is a possibility that droplets adhere to the nozzle surface due to humidification around the nozzle surface, and the droplets may drip onto the print medium. In addition, printing apparatuses using a droplet discharge head include a printing apparatus that heats a print medium in order to promote drying of discharged droplets. Some printing apparatuses include a cooling device attached to the droplet discharge head in order to suppress a temperature rise of the droplet discharge head due to heating of the print medium. In such a droplet discharge head, drying of the droplet discharge head can be prevented by suppressing the temperature rise of the droplet discharge head. However, even in a droplet discharge head equipped with a cooling device, condensation may occur on the nozzle surface due to a drop in the temperature of the droplet discharge head, and the droplet may fall on the print medium. The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a droplet discharge head that can prevent drying and suppress drop of droplets on a print medium.

  In order to solve the above problems, a droplet discharge head according to claim 1 of the present application is a droplet discharge head that discharges droplets onto a print medium, and has nozzle holes for discharging the droplets. A head surface and a cooling device for cooling the head body, wherein a nozzle surface in which the nozzle hole of the head body opens is formed around the opening of the nozzle hole, and has an affinity for liquid The lyophobic region is a low-lying region, and (b) a lyophilic region that is formed so as to surround the lyophobic region and has a higher affinity than the lyophobic region.

  According to a second aspect of the present invention, there is provided the liquid droplet ejection head according to the first aspect, wherein the liquid droplet ejection head has a suction mechanism that communicates with the lyophilic region and sucks a liquid that is compatible with the lyophilic region. It is characterized by providing.

  Further, in the liquid droplet ejection head according to claim 3, in the liquid droplet ejection head according to claim 2, the suction mechanism has a porous body in which many pores are formed, and the lyophilic region The liquid having affinity for is sucked into the pores of the porous body.

  In addition, in the droplet discharge head according to claim 4, in the droplet discharge head according to claim 2 or 3, the suction mechanism includes a pump, and the lyophilic region is activated by the pump. It is characterized by sucking a liquid that is compatible with.

  According to a fifth aspect of the present invention, there is provided a printing apparatus comprising: a stage that supports a print medium; a droplet discharge head that discharges droplets onto the print medium supported by the stage; and a print medium supported by the stage. A printing apparatus including a heater for heating, wherein the droplet discharge head includes a head body in which nozzle holes for discharging droplets are formed, and a cooling device for cooling the head body. A nozzle surface on which the nozzle hole of the head main body is opened is (a) a liquid repellent area which is formed around the nozzle hole opening and has a low affinity with the liquid; and (b) the liquid repellent area. The lyophilic region is formed so as to surround the region and has a higher affinity than the lyophobic region.

  In the droplet discharge head according to claim 1 and the printing apparatus according to claim 5, a cooling device is mounted on the head main body of the droplet discharge head. Thereby, drying of the droplet discharge head can be prevented by suppressing the temperature rise of the droplet discharge head. In addition, a liquid repellent area, which is a low affinity area for the liquid, is formed around the opening of the nozzle hole on the nozzle surface of the droplet discharge head, and has a higher affinity than the liquid repellent area so as to surround the liquid repellent area A lyophilic region, which is a region, is formed. Thereby, the droplets adhering to the nozzle surface gather in the lyophilic region having high affinity. The water droplets collected in the lyophilic area are adapted to the lyophilic area and the contact angle becomes small. Incidentally, the contact angle is an angle formed by a tangent passing through the surface of the droplet and the nozzle surface. When the contact angle decreases, the wettability between the droplet and the nozzle surface increases, and the droplet is difficult to drip. Therefore, according to the droplet discharge head according to claim 1 and the printing apparatus according to claim 5, it is possible to prevent the droplet discharge head from being dried and to suppress the droplet from falling onto the print medium. It becomes possible.

  Further, the droplet discharge head according to claim 2 is provided with a suction mechanism for sucking the liquid having affinity with the lyophilic region. As a result, the droplets collected in the lyophilic area can be removed from the nozzle surface, and the droplets can be reliably prevented from dropping onto the print medium.

  In the droplet discharge head according to the third aspect, the droplets collected in the lyophilic region are sucked by the porous body in which many pores are formed. Thereby, the structure of the suction mechanism can be simplified.

  In the droplet discharge head according to the fourth aspect, the droplets collected in the lyophilic region are sucked by the suction force of the pump. Thereby, it is possible to reliably suck the droplets collected in the lyophilic region.

1 is a perspective view showing a printing apparatus that is an embodiment of the present invention. FIG. 2 is a plan view illustrating a bottom surface of an ejection head included in the printing apparatus illustrated in FIG. 1. It is sectional drawing in the AA line of FIG. It is a block diagram which shows the control apparatus with which a printing apparatus is provided. FIG. 10 is a plan view illustrating a bottom surface of an ejection head included in a printing apparatus according to a first modification. FIG. 10 is a plan view illustrating a bottom surface of an ejection head provided in a printing apparatus according to a second modification. It is sectional drawing in the BB line of FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments and modifications of the present invention will be described in detail with reference to the drawings as modes for carrying out the present invention.

<Configuration of printing device>
FIG. 1 shows a printing apparatus 10 according to an embodiment of the present invention. The printing apparatus 10 is an apparatus for printing a circuit pattern on the circuit board 12. The printing apparatus 10 includes an ejection head 20, a stage 22, and an ejection head moving device (see FIG. 4) 24.

  The ejection head 20 is an inkjet type ejection head, and ejects conductive ink, specifically, a silver nanoparticle paste. Thereby, a circuit pattern is printed on the circuit board 12. The discharge head 20 includes a head main body 30, a hygroscopic material 32, and a cooling mechanism 34.

  As shown in FIGS. 2 and 3, the head main body 30 has a plurality of nozzle holes 36 for discharging conductive ink. FIG. 2 is a view showing the ejection head 20 from the viewpoint from below, and FIG. 3 is a cross-sectional view taken along the line AA in FIG. The plurality of nozzle holes 36 open to the lower end surface of the head body 30, that is, the nozzle surface 38 at one end. Then, in accordance with the electrical signal, the conductive ink is ejected from the nozzle surface 38 of the head main body 30 using the piezoelectric element (see FIG. 4) 40 or vapor bubbles caused by heat as a driving source.

  The outer edge portion of the nozzle surface 38 of the head body 30 is subjected to a process for increasing the affinity with the liquid, specifically, an etching process. Then, inside the region 50 (hereinafter referred to as “lyophilic region”) subjected to the etching treatment, a treatment for improving the liquid repellency, specifically, a surface treatment with a fluorine coating agent is performed. . The plurality of nozzle holes 36 are open in a region 52 (hereinafter referred to as “liquid repellent region”) that has been surface-treated with a fluorine coating agent. That is, the liquid repellent area 52 is formed around the openings of the plurality of nozzle holes 36, and the lyophilic area 50 is formed so as to surround the liquid repellent area 52.

  The hygroscopic material 32 is formed of porous ceramics and generally has a rectangular tube shape. The internal dimensions of the rectangular tube-shaped hygroscopic material 32 are substantially the same as the external dimensions of the side wall surface of the head body 30. The head main body 30 is fitted inside the hygroscopic material 32 in a state where the inner peripheral surface of the hygroscopic material 32 and the side wall surface of the head main body 30 are in close contact with each other. Incidentally, the lower end of the hygroscopic material 32 and the nozzle surface 38 of the head body 30 are flush with each other. Thereby, the lyophilic region 50 formed at the outer edge portion of the nozzle surface 38 communicates with the hygroscopic material 32.

  The cooling mechanism 34 has a housing 56 having a generally rectangular tube shape. The inner dimension of the rectangular tube-shaped housing 56 is substantially the same as the outer dimension of the outer peripheral surface of the hygroscopic material 32. The hygroscopic material 32 is fitted into the housing 56 in a state where the inner peripheral surface of the housing 56 and the outer peripheral surface of the hygroscopic material 32 are in close contact with each other. That is, the hygroscopic material 32 is fitted on the outer wall surface of the head body 30, and the housing 56 is fitted on the outer peripheral surface of the hygroscopic material 32. In addition, cooling water is circulated inside the housing 56. With such a structure, the cooling mechanism 34 cools the head main body 30 via the hygroscopic material 32.

  The stage 22 supports the circuit board 12 as shown in FIG. The stage 22 has a heater (see FIG. 4) 58, and the circuit board 12 supported by the stage 22 is heated by the heater 58.

  The discharge head moving device 24 is an XY robot type moving device, and moves the discharge head 20 to an arbitrary position on the stage 22. Specifically, the ejection head moving device 24 includes an electromagnetic motor (see FIG. 4) 60 that slides a slider (not shown) in a predetermined direction along a horizontal plane, and an electromagnetic motor that slides in a horizontal direction perpendicular to the predetermined direction. (See FIG. 4) 62. The ejection head 20 is attached to the slider, and the ejection head moving device 24 moves the ejection head 20 to an arbitrary position on the stage 22 by the operation of the two electromagnetic motors 60 and 62.

  The printing apparatus 10 includes a control device 70 as shown in FIG. The control device 70 includes a controller 72, a plurality of drive circuits 74, and a control circuit 76. The plurality of drive circuits 74 are connected to the piezoelectric element 40 and the electromagnetic motors 60 and 62. The control circuit 76 is connected to the heater 58. The controller 72 includes a CPU, a ROM, a RAM, and the like and is mainly a computer, and is connected to a plurality of drive circuits 74 and a control circuit 76. Thereby, the operation of the ejection head 20 and the ejection head moving device 24 and the temperature of the stage 22 are controlled by the controller 72.

<Operation of printing device>
With the configuration described above, in the printing apparatus 10, the circuit pattern is printed by discharging conductive ink onto the upper surface of the circuit board 12. Specifically, first, the circuit board 12 is placed on the stage 22. At this time, the stage 22 is heated by the heater 58. Then, the ejection head 20 moves above the circuit board 12 according to a command from the controller 72 of the control device 70. Subsequently, the ejection head 20 ejects conductive ink onto the upper surface of the circuit board 12, and a circuit pattern is printed.

  Heat of the heated stage 22 is transmitted to the circuit board 12 on which the circuit pattern is printed. For this reason, the circuit board 12 is heated, and drying of the printed circuit pattern is promoted. As a result, the time required for the printing work on the circuit board 12 can be shortened.

  On the other hand, there is a possibility that the discharge head 20 positioned on the stage 22 is dried by heating the stage 22. Drying the ejection head 20 is not preferable because it causes ejection failure due to clogging of the nozzle holes 36 or the like. Therefore, a cooling mechanism 34 is attached to the head main body 30 of the ejection head 20, and the head main body 30 is cooled by circulation of the cooling water. Thereby, the temperature rise of the head main body 30 can be suppressed, and the nozzle hole 36 can be prevented from being clogged.

  However, when the head main body 30 is cooled, water vapor in the air is condensed due to condensation, and water droplets may adhere to the nozzle surface 38. The water droplets adhering to the nozzle surface 38 may drop on the circuit board 12, and it is desirable to prevent the water droplets from dropping. In view of this, a lyophilic region 50 and a liquid repellent region 52 are formed on the nozzle surface 38.

  Specifically, a liquid repellent region 52 is formed around the opening of the nozzle hole 36 on the nozzle surface 38 to ensure stable ink ejection. If the lyophilic area 50 is formed around the opening of the nozzle hole 36, the ink discharged from the nozzle hole 36 may become familiar with the lyophilic area 50 around the opening, and ink may not be appropriately discharged. Because. In addition, a lyophilic region 50 is formed so as to surround the liquid repellent region 52.

  Thereby, water droplets adhering to the nozzle surface 38 gather in the lyophilic region 50 having high affinity. Since the water droplets collected in the lyophilic area 50 are adapted to the lyophilic area 50, the contact angle becomes small. Incidentally, the contact angle is an angle formed between the tangent passing through the surface of the water droplet and the nozzle surface 38. When the contact angle decreases, the wettability between the water droplet and the nozzle surface 38 increases, and it becomes difficult for the water droplet to drip. In this way, the ejection head 20 prevents the dripping of water droplets.

  Further, the ejection head 20 is provided with a hygroscopic material 32 in communication with the lyophilic region 50. For this reason, the water droplets collected in the lyophilic region 50 are sucked into the hygroscopic material 32 by capillary action. Thereby, it is possible to remove water droplets from the nozzle surface 38, and it is possible to reliably prevent the water droplets from dropping onto the circuit board 12. Note that the water droplets sucked by the hygroscopic material 32 evaporate from many pores.

  When the nozzle hole 36 is clogged, nozzle hole cleaning is performed. In the nozzle hole cleaning, ink in a state where a predetermined pressure is applied is ejected from the nozzle hole 36. Thereby, clogging of the nozzle hole 36 and the like are eliminated. On the other hand, there is a possibility that the ejected ink may adhere to the periphery of the opening of the nozzle hole 36, and it is necessary to perform a wiping operation of the nozzle surface 38 after cleaning the nozzle hole. However, in the ejection head 20, the ink attached around the opening of the nozzle hole 36 is also sucked by the moisture absorbent 32 through the lyophilic region 50, as in the case of water droplets. Thereby, it becomes possible to omit the wiping work of the nozzle surface 38 after the nozzle hole cleaning.

<Modification>
The lyophilic area 50 is formed on the outer edge of the nozzle surface 38 of the ejection head 20 of the above embodiment, and the lyophobic area 52 is formed inside the lyophilic area 50. Various patterns can be adopted as a formation pattern with the region 52. An ejection head in which a pattern different from the formation pattern of the lyophilic area 50 and the liquid repellent area 52 in the above embodiment is adopted is shown in FIG. Since the ejection head 80 of the modified example has the same configuration as the ejection head 20 except for the formation pattern of the lyophilic area and the liquid repellent area, the same reference numerals are used for components having the same functions as the ejection head 20. The description will be omitted or simplified using.

  A first liquid repellent region 84 is formed around the plurality of nozzle holes 36 on the nozzle surface 82 of the ejection head 80. An annular first lyophilic region 86 is formed so as to surround the first liquid repellent region 84. Further, a plurality of second lyophilic regions 88 that connect the first lyophilic region 86 and the outer edge portion of the nozzle surface 82 are formed outside the first lyophilic region 86. That is, the first lyophilic area 86 communicates with the hygroscopic material 32 via the second lyophilic area 88. A second lyophobic region 90 is formed at a location where the second lyophilic region 88 outside the first lyophilic region 86 is not formed.

  Due to the formation pattern of the liquid repellent regions 84 and 90 and the lyophilic regions 86 and 88, water droplets, ink, and the like attached to the nozzle surface 82 are guided to the moisture absorbent 32 and removed from the nozzle surface 82. Specifically, for example, water droplets or the like attached to the first liquid repellent area 84 are guided to the first lyophilic area 86 by affinity. Then, water droplets or the like guided to the first lyophilic region 86 are guided to the moisture absorbent material 32 via the second lyophilic region 88. Thereby, water droplets and the like are removed from the nozzle surface 82.

  In the ejection heads 20 and 80, the moisture absorbing material 32 formed of porous ceramics is used as a suction mechanism for sucking water droplets or the like. However, other types of suction mechanisms can be used. It is. An ejection head that employs a suction mechanism of a type different from that of the hygroscopic material 32 is shown in FIGS. 6 and 7 as an ejection head 100 of a modification. Since the ejection head 100 of the modified example has the same configuration as the ejection heads 20 and 80 except for the suction mechanism and the formation pattern of the lyophilic area and the liquid repellent area, it has the same function as the ejection heads 20 and 80. The description of the constituent elements will be omitted or simplified by using the same reference numerals.

  A first liquid repellent region 104 is formed around the plurality of nozzle holes 36 on the nozzle surface 102 of the ejection head 100. An annular lyophilic region 106 is formed so as to surround the first liquid repellent region 104. Further, a second lyophobic region 108 is formed outside the lyophilic region 106.

  As shown in FIG. 7, a plurality of through holes 112 are formed in the head main body 110 of the discharge head 100 so as to extend in the vertical direction. The lower end portion of each through hole 112 opens into the lyophilic region 106 of the nozzle surface 102. On the other hand, the upper end portion of each through hole 112 is open to the upper end surface of the head body 110. And the upper end part of each through-hole 112 is connected to the pump 116 via the connection path 114.

  With the structure described above, water droplets, ink, and the like attached to the nozzle surface 102 are removed from the nozzle surface 102 even in the ejection head 100. Specifically, for example, water droplets or the like attached to the first liquid repellent area 104 are guided to the lyophilic area 106 by affinity. Then, water droplets or the like guided to the lyophilic region 106 are sucked into the pump 116 through the through hole 112 and the connection path 114. Thereby, water droplets and the like are removed from the nozzle surface 102.

  Incidentally, in the above-described embodiment, the printing apparatus 10 is an example of a printing apparatus. The circuit board 12 is an example of a print medium. The ejection heads 20, 80, 100 are an example of a droplet ejection head. The stage 22 is an example of a stage. The head main bodies 30 and 110 are examples of the head main body. The hygroscopic material 32 is an example of a porous body and a suction mechanism. The cooling mechanism 34 is an example of a cooling device. The nozzle hole 36 is an example of a nozzle hole. The nozzle surfaces 38, 82, and 102 are examples of nozzle surfaces. The lyophilic areas 50, 86, 88, and 106 are examples of the lyophilic area. The liquid repellent areas 52, 84, 90, 104, and 108 are examples of the liquid repellent area. The heater 58 is an example of a heater. The mechanism constituted by the through hole 112, the connection path 114, and the pump 116 is an example of a suction mechanism. The pump 116 is an example of a pump.

  In addition, this invention is not limited to the said Example and modification, It is possible to implement in the various aspect which gave various change and improvement based on the knowledge of those skilled in the art. Specifically, for example, in the above-described embodiments and modifications, the hygroscopic material 32 is formed of porous ceramics, but is formed of a material having many pores. It is possible. Specifically, for example, porous silica, rigid polyurethane foam, or the like can be adopted as a material having many pores.

  Further, in the above modification, water droplets and the like are sucked from the through hole 112 by the suction force of the pump 116, but it is possible to suck water droplets and the like from the through hole 112 without providing the pump 116. Specifically, by making the inner diameter of the through hole 112 smaller than a predetermined diameter, it is possible to suck water droplets or the like from the through hole 112 by capillary action. That is, even in the ejection head excluding the connection path 114 and the pump 116 from the ejection head 100, it is possible to remove water droplets and the like from the nozzle surface 102.

  In the above embodiment, conductive ink is used as the liquid to be ejected, but various liquids can be used. Specifically, for example, it is possible to employ ink capable of printing a resin pattern, dye-based ink, pigment-based ink, and the like. Furthermore, the print medium is not limited to a circuit board, and various print media can be employed. Specifically, for example, a substrate having a chip, paper, or the like can be employed.

  DESCRIPTION OF SYMBOLS 10: Printing apparatus 12: Circuit board (printing medium) 20: Discharge head (droplet discharge head) 22: Stage 30: Head main body 32: Hygroscopic material (porous body) (suction mechanism) 34: Cooling mechanism (cooling apparatus) 36: Nozzle hole 38: Nozzle surface 50: Lipophilic region 52: Liquid repellent region 58: Heater 80: Discharge head (droplet discharge head) 82: Nozzle surface 84: Liquid repellent region 86: Lipophilic region 88: Lipophilic region 90: Liquid repellent area 100: Discharge head (droplet discharge head) 102: Nozzle surface 104: Liquid repellent area 106: Lipophilic area 108: Liquid repellent area 110: Head body 112: Through hole (suction mechanism) 114: Connection path (Suction mechanism) 116: Pump (Suction mechanism) (Pump)

  The present invention relates to a droplet discharge head that discharges droplets onto a print medium, and a printing apparatus that includes the droplet discharge head.

  When the droplet is not ejected for a long time, the nozzle surface of the droplet ejection head is dried, and the viscosity of the ink or the like may be increased. Ink with increased viscosity may not be able to perform stable printing, and it is desirable to prevent drying of the nozzle surface of the droplet discharge head. For this reason, in the droplet discharge head described in the following patent document, the liquid for preventing drying is evaporated on the nozzle surface and the periphery of the nozzle surface is humidified.

JP 2010-69635 A

  According to the above patent document, it is possible to prevent the droplet discharge head from being dried by humidification around the nozzle surface. However, there is a possibility that droplets adhere to the nozzle surface due to humidification around the nozzle surface, and the droplets may drip onto the print medium. In addition, printing apparatuses using a droplet discharge head include a printing apparatus that heats a print medium in order to promote drying of discharged droplets. Some printing apparatuses include a cooling device attached to the droplet discharge head in order to suppress a temperature rise of the droplet discharge head due to heating of the print medium. In such a droplet discharge head, drying of the droplet discharge head can be prevented by suppressing the temperature rise of the droplet discharge head. However, even in a droplet discharge head equipped with a cooling device, condensation may occur on the nozzle surface due to a drop in the temperature of the droplet discharge head, and the droplet may fall on the print medium. The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a droplet discharge head that can prevent drying and suppress drop of droplets on a print medium.

In order to solve the above problems, a droplet discharge head according to claim 1 of the present application is a droplet discharge head that discharges droplets onto a printing medium, and has a plurality of nozzle holes for discharging droplets. A head body formed on a lower surface side ; and a cooling device for cooling the head body, wherein the nozzle surface on which the plurality of nozzle holes of the head body are opened is (a) a periphery of the openings of the plurality of nozzle holes A first liquid-repellent region that is a region having a low affinity with the liquid, and (b) a region that is formed so as to surround the first liquid-repellent region and has a higher affinity than the liquid-repellent region. An annular lyophilic region; and (c) a second lyophobic region formed outside the annular lyophilic region. The lyophilic region extends vertically in the head body, and an upper end portion of the head body. Open to the upper surface side, the lower end is the nozzle surface A plurality of through-holes opening in the liquid region are formed, and the plurality of through-holes function as a suction mechanism that sucks liquid having affinity with the lyophilic region, and each of the plurality of through-holes inner dimensions of the opening to the lyophilic areas, wherein the same der Rukoto to the width of the lyophilic area of the annular.

The droplet discharge head according to claim 2 is the droplet discharge head according to claim 1, wherein the plurality of through-holes have a pitch that is an integral multiple of a formation pitch of the plurality of nozzle holes. It is characterized by opening in the liquid region .

Further, in the droplet discharge head according to claim 3, in the droplet discharge head according to claim 1 or 2, the suction mechanism has a porous body in which many pores are formed, The liquid having affinity for the lyophilic region is sucked into the pores of the porous body.

Further, in the droplet ejection head according to claim 4, in the liquid droplet ejection head according to claims 1 or one of claims 3, wherein the suction mechanism has a pump, by the operation of the pump The liquid having affinity for the lyophilic region is sucked from the plurality of through holes .

According to a fifth aspect of the present invention, there is provided a printing apparatus comprising: a stage that supports a print medium; a droplet discharge head that discharges droplets onto the print medium supported by the stage; and a print medium supported by the stage. In a printing apparatus provided with a heater for heating, the droplet discharge head includes a head body in which a plurality of nozzle holes for discharging droplets are formed on a lower surface side, and a cooling device that cools the head body A nozzle surface in which the plurality of nozzle holes of the head body are open is formed around the openings of the plurality of nozzle holes, and is a first repellent that is a region having a low affinity with the liquid. A liquid region; (b) an annular lyophilic region that is formed so as to surround the first lyophobic region and has a higher affinity than the lyophobic region; and (c) an outer side of the annular lyophilic region. Second liquid repellent formed on Is constituted by a band, extends vertically to the head main body, an upper end portion opened to the upper surface of the head body, a plurality of through-holes having a lower end open to the lyophilic area of the nozzle surface is formed And the plurality of through holes function as a suction mechanism for sucking the liquid having affinity for the lyophilic region, and the inner dimensions of the openings to the lyophilic region of each of the plurality of through holes, wherein the same der Rukoto to the width of the lyophilic area of the annular.

In the droplet discharge head according to claim 1 and the printing apparatus according to claim 5, a cooling device is mounted on the head main body of the droplet discharge head. Thereby, drying of the droplet discharge head can be prevented by suppressing the temperature rise of the droplet discharge head. In addition, a liquid repellent area, which is a low affinity area for the liquid, is formed around the opening of the nozzle hole on the nozzle surface of the droplet discharge head, and has a higher affinity than the liquid repellent area so as to surround the liquid repellent area. A lyophilic region, which is a region, is formed. Thereby, the droplets adhering to the nozzle surface gather in the lyophilic region having high affinity. The water droplets collected in the lyophilic area are adapted to the lyophilic area and the contact angle becomes small. Incidentally, the contact angle is an angle formed by a tangent passing through the surface of the droplet and the nozzle surface. When the contact angle decreases, the wettability between the droplet and the nozzle surface increases, and the droplet is difficult to drip. Therefore, according to the droplet discharge head according to claim 1 and the printing apparatus according to claim 5, it is possible to prevent the droplet discharge head from being dried and to suppress the droplet from falling onto the print medium. It becomes possible. The head main body is formed with a plurality of through holes extending in the vertical direction, and the plurality of through holes open to the lyophilic region and suck the liquid having affinity with the lyophilic region. As a result, the droplets collected in the lyophilic area can be removed from the nozzle surface, and the droplets can be reliably prevented from dropping onto the print medium. Furthermore, the internal dimension of the opening to each lyophilic region of each of the plurality of through holes is the same as the width of the annular lyophilic region, and moisture is preferably sucked from the plurality of through holes.

Further, in the liquid droplet ejection head according to claim 2 , the plurality of through holes open to the lyophilic region at a pitch that is an integral multiple of the formation pitch of the plurality of nozzle holes, and preferably from the plurality of through holes. Moisture is aspirated.

  In the droplet discharge head according to the third aspect, the droplets collected in the lyophilic region are sucked by the porous body in which many pores are formed. Thereby, the structure of the suction mechanism can be simplified.

  In the droplet discharge head according to the fourth aspect, the droplets collected in the lyophilic region are sucked by the suction force of the pump. Thereby, it is possible to reliably suck the droplets collected in the lyophilic region.

1 is a perspective view showing a printing apparatus that is an embodiment of the present invention. FIG. 2 is a plan view illustrating a bottom surface of an ejection head included in the printing apparatus illustrated in FIG. 1. It is sectional drawing in the AA line of FIG. It is a block diagram which shows the control apparatus with which a printing apparatus is provided. FIG. 10 is a plan view illustrating a bottom surface of an ejection head included in a printing apparatus according to a first modification. FIG. 10 is a plan view illustrating a bottom surface of an ejection head provided in a printing apparatus according to a second modification. It is sectional drawing in the BB line of FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments and modifications of the present invention will be described in detail with reference to the drawings as modes for carrying out the present invention.

<Configuration of printing device>
FIG. 1 shows a printing apparatus 10 according to an embodiment of the present invention. The printing apparatus 10 is an apparatus for printing a circuit pattern on the circuit board 12. The printing apparatus 10 includes an ejection head 20, a stage 22, and an ejection head moving device (see FIG. 4) 24.

  The ejection head 20 is an inkjet type ejection head, and ejects conductive ink, specifically, a silver nanoparticle paste. Thereby, a circuit pattern is printed on the circuit board 12. The discharge head 20 includes a head main body 30, a hygroscopic material 32, and a cooling mechanism 34.

  As shown in FIGS. 2 and 3, the head main body 30 has a plurality of nozzle holes 36 for discharging conductive ink. FIG. 2 is a view showing the ejection head 20 from the viewpoint from below, and FIG. 3 is a cross-sectional view taken along the line AA in FIG. The plurality of nozzle holes 36 open to the lower end surface of the head body 30, that is, the nozzle surface 38 at one end. Then, in accordance with the electrical signal, the conductive ink is ejected from the nozzle surface 38 of the head main body 30 using the piezoelectric element (see FIG. 4) 40 or vapor bubbles caused by heat as a driving source.

  The outer edge portion of the nozzle surface 38 of the head body 30 is subjected to a process for increasing the affinity with the liquid, specifically, an etching process. Then, inside the region 50 (hereinafter referred to as “lyophilic region”) subjected to the etching treatment, a treatment for improving the liquid repellency, specifically, a surface treatment with a fluorine coating agent is performed. . The plurality of nozzle holes 36 are open in a region 52 (hereinafter referred to as “liquid repellent region”) that has been surface-treated with a fluorine coating agent. That is, the liquid repellent area 52 is formed around the openings of the plurality of nozzle holes 36, and the lyophilic area 50 is formed so as to surround the liquid repellent area 52.

  The hygroscopic material 32 is formed of porous ceramics and generally has a rectangular tube shape. The internal dimensions of the rectangular tube-shaped hygroscopic material 32 are substantially the same as the external dimensions of the side wall surface of the head body 30. The head main body 30 is fitted inside the hygroscopic material 32 in a state where the inner peripheral surface of the hygroscopic material 32 and the side wall surface of the head main body 30 are in close contact with each other. Incidentally, the lower end of the hygroscopic material 32 and the nozzle surface 38 of the head body 30 are flush with each other. Thereby, the lyophilic region 50 formed at the outer edge portion of the nozzle surface 38 communicates with the hygroscopic material 32.

  The cooling mechanism 34 has a housing 56 having a generally rectangular tube shape. The inner dimension of the rectangular tube-shaped housing 56 is substantially the same as the outer dimension of the outer peripheral surface of the hygroscopic material 32. The hygroscopic material 32 is fitted into the housing 56 in a state where the inner peripheral surface of the housing 56 and the outer peripheral surface of the hygroscopic material 32 are in close contact with each other. That is, the hygroscopic material 32 is fitted on the outer wall surface of the head body 30, and the housing 56 is fitted on the outer peripheral surface of the hygroscopic material 32. In addition, cooling water is circulated inside the housing 56. With such a structure, the cooling mechanism 34 cools the head main body 30 via the hygroscopic material 32.

  The stage 22 supports the circuit board 12 as shown in FIG. The stage 22 has a heater (see FIG. 4) 58, and the circuit board 12 supported by the stage 22 is heated by the heater 58.

  The discharge head moving device 24 is an XY robot type moving device, and moves the discharge head 20 to an arbitrary position on the stage 22. Specifically, the ejection head moving device 24 includes an electromagnetic motor (see FIG. 4) 60 that slides a slider (not shown) in a predetermined direction along a horizontal plane, and an electromagnetic motor that slides in a horizontal direction perpendicular to the predetermined direction. (See FIG. 4) 62. The ejection head 20 is attached to the slider, and the ejection head moving device 24 moves the ejection head 20 to an arbitrary position on the stage 22 by the operation of the two electromagnetic motors 60 and 62.

  The printing apparatus 10 includes a control device 70 as shown in FIG. The control device 70 includes a controller 72, a plurality of drive circuits 74, and a control circuit 76. The plurality of drive circuits 74 are connected to the piezoelectric element 40 and the electromagnetic motors 60 and 62. The control circuit 76 is connected to the heater 58. The controller 72 includes a CPU, a ROM, a RAM, and the like and is mainly a computer, and is connected to a plurality of drive circuits 74 and a control circuit 76. Thereby, the operation of the ejection head 20 and the ejection head moving device 24 and the temperature of the stage 22 are controlled by the controller 72.

<Operation of printing device>
With the configuration described above, in the printing apparatus 10, the circuit pattern is printed by discharging conductive ink onto the upper surface of the circuit board 12. Specifically, first, the circuit board 12 is placed on the stage 22. At this time, the stage 22 is heated by the heater 58. Then, the ejection head 20 moves above the circuit board 12 according to a command from the controller 72 of the control device 70. Subsequently, the ejection head 20 ejects conductive ink onto the upper surface of the circuit board 12, and a circuit pattern is printed.

  Heat of the heated stage 22 is transmitted to the circuit board 12 on which the circuit pattern is printed. For this reason, the circuit board 12 is heated, and drying of the printed circuit pattern is promoted. As a result, the time required for the printing work on the circuit board 12 can be shortened.

  On the other hand, there is a possibility that the discharge head 20 positioned on the stage 22 is dried by heating the stage 22. Drying the ejection head 20 is not preferable because it causes ejection failure due to clogging of the nozzle holes 36 or the like. Therefore, a cooling mechanism 34 is attached to the head main body 30 of the ejection head 20, and the head main body 30 is cooled by circulation of the cooling water. Thereby, the temperature rise of the head main body 30 can be suppressed, and the nozzle hole 36 can be prevented from being clogged.

  However, when the head main body 30 is cooled, water vapor in the air is condensed due to condensation, and water droplets may adhere to the nozzle surface 38. The water droplets adhering to the nozzle surface 38 may drop on the circuit board 12, and it is desirable to prevent the water droplets from dropping. In view of this, a lyophilic region 50 and a liquid repellent region 52 are formed on the nozzle surface 38.

  Specifically, a liquid repellent region 52 is formed around the opening of the nozzle hole 36 on the nozzle surface 38 to ensure stable ink ejection. If the lyophilic area 50 is formed around the opening of the nozzle hole 36, the ink discharged from the nozzle hole 36 may become familiar with the lyophilic area 50 around the opening, and ink may not be appropriately discharged. Because. In addition, a lyophilic region 50 is formed so as to surround the liquid repellent region 52.

  Thereby, water droplets adhering to the nozzle surface 38 gather in the lyophilic region 50 having high affinity. Since the water droplets collected in the lyophilic area 50 are adapted to the lyophilic area 50, the contact angle becomes small. Incidentally, the contact angle is an angle formed between the tangent passing through the surface of the water droplet and the nozzle surface 38. When the contact angle decreases, the wettability between the water droplet and the nozzle surface 38 increases, and it becomes difficult for the water droplet to drip. In this way, the ejection head 20 prevents the dripping of water droplets.

  Further, the ejection head 20 is provided with a hygroscopic material 32 in communication with the lyophilic region 50. For this reason, the water droplets collected in the lyophilic region 50 are sucked into the hygroscopic material 32 by capillary action. Thereby, it is possible to remove water droplets from the nozzle surface 38, and it is possible to reliably prevent the water droplets from dropping onto the circuit board 12. Note that the water droplets sucked by the hygroscopic material 32 evaporate from many pores.

  When the nozzle hole 36 is clogged, nozzle hole cleaning is performed. In the nozzle hole cleaning, ink in a state where a predetermined pressure is applied is ejected from the nozzle hole 36. Thereby, clogging of the nozzle hole 36 and the like are eliminated. On the other hand, there is a possibility that the ejected ink may adhere to the periphery of the opening of the nozzle hole 36, and it is necessary to perform a wiping operation of the nozzle surface 38 after cleaning the nozzle hole. However, in the ejection head 20, the ink attached around the opening of the nozzle hole 36 is also sucked by the moisture absorbent 32 through the lyophilic region 50, as in the case of water droplets. Thereby, it becomes possible to omit the wiping work of the nozzle surface 38 after the nozzle hole cleaning.

<Modification>
The lyophilic area 50 is formed on the outer edge of the nozzle surface 38 of the ejection head 20 of the above embodiment, and the lyophobic area 52 is formed inside the lyophilic area 50. Various patterns can be adopted as a formation pattern with the region 52. An ejection head in which a pattern different from the formation pattern of the lyophilic area 50 and the liquid repellent area 52 in the above embodiment is adopted is shown in FIG. Since the ejection head 80 of the modified example has the same configuration as the ejection head 20 except for the formation pattern of the lyophilic area and the liquid repellent area, the same reference numerals are used for components having the same functions as the ejection head 20. The description will be omitted or simplified using.

  A first liquid repellent region 84 is formed around the plurality of nozzle holes 36 on the nozzle surface 82 of the ejection head 80. An annular first lyophilic region 86 is formed so as to surround the first liquid repellent region 84. Further, a plurality of second lyophilic regions 88 that connect the first lyophilic region 86 and the outer edge portion of the nozzle surface 82 are formed outside the first lyophilic region 86. That is, the first lyophilic area 86 communicates with the hygroscopic material 32 via the second lyophilic area 88. A second lyophobic region 90 is formed at a location where the second lyophilic region 88 outside the first lyophilic region 86 is not formed.

  Due to the formation pattern of the liquid repellent regions 84 and 90 and the lyophilic regions 86 and 88, water droplets, ink, and the like attached to the nozzle surface 82 are guided to the moisture absorbent 32 and removed from the nozzle surface 82. Specifically, for example, water droplets or the like attached to the first liquid repellent area 84 are guided to the first lyophilic area 86 by affinity. Then, water droplets or the like guided to the first lyophilic region 86 are guided to the moisture absorbent material 32 via the second lyophilic region 88. Thereby, water droplets and the like are removed from the nozzle surface 82.

  In the ejection heads 20 and 80, the moisture absorbing material 32 formed of porous ceramics is used as a suction mechanism for sucking water droplets or the like. However, other types of suction mechanisms can be used. It is. An ejection head that employs a suction mechanism of a type different from that of the hygroscopic material 32 is shown in FIGS. 6 and 7 as an ejection head 100 of a modification. Since the ejection head 100 of the modified example has the same configuration as the ejection heads 20 and 80 except for the suction mechanism and the formation pattern of the lyophilic area and the liquid repellent area, it has the same function as the ejection heads 20 and 80. The description of the constituent elements will be omitted or simplified by using the same reference numerals.

  A first liquid repellent region 104 is formed around the plurality of nozzle holes 36 on the nozzle surface 102 of the ejection head 100. An annular lyophilic region 106 is formed so as to surround the first liquid repellent region 104. Further, a second lyophobic region 108 is formed outside the lyophilic region 106.

  As shown in FIG. 7, a plurality of through holes 112 are formed in the head main body 110 of the discharge head 100 so as to extend in the vertical direction. The lower end portion of each through hole 112 opens into the lyophilic region 106 of the nozzle surface 102. On the other hand, the upper end portion of each through hole 112 is open to the upper end surface of the head body 110. And the upper end part of each through-hole 112 is connected to the pump 116 via the connection path 114.

  With the structure described above, water droplets, ink, and the like attached to the nozzle surface 102 are removed from the nozzle surface 102 even in the ejection head 100. Specifically, for example, water droplets or the like attached to the first liquid repellent area 104 are guided to the lyophilic area 106 by affinity. Then, water droplets or the like guided to the lyophilic region 106 are sucked into the pump 116 through the through hole 112 and the connection path 114. Thereby, water droplets and the like are removed from the nozzle surface 102.

  Incidentally, in the above-described embodiment, the printing apparatus 10 is an example of a printing apparatus. The circuit board 12 is an example of a print medium. The ejection heads 20, 80, 100 are an example of a droplet ejection head. The stage 22 is an example of a stage. The head main bodies 30 and 110 are examples of the head main body. The hygroscopic material 32 is an example of a porous body and a suction mechanism. The cooling mechanism 34 is an example of a cooling device. The nozzle hole 36 is an example of a nozzle hole. The nozzle surfaces 38, 82, and 102 are examples of nozzle surfaces. The lyophilic areas 50, 86, 88, and 106 are examples of the lyophilic area. The liquid repellent areas 52, 84, 90, 104, and 108 are examples of the liquid repellent area. The heater 58 is an example of a heater. The mechanism constituted by the through hole 112, the connection path 114, and the pump 116 is an example of a suction mechanism. The pump 116 is an example of a pump.

  In addition, this invention is not limited to the said Example and modification, It is possible to implement in the various aspect which gave various change and improvement based on the knowledge of those skilled in the art. Specifically, for example, in the above-described embodiments and modifications, the hygroscopic material 32 is formed of porous ceramics, but is formed of a material having many pores. It is possible. Specifically, for example, porous silica, rigid polyurethane foam, or the like can be adopted as a material having many pores.

  Further, in the above modification, water droplets and the like are sucked from the through hole 112 by the suction force of the pump 116, but it is possible to suck water droplets and the like from the through hole 112 without providing the pump 116. Specifically, by making the inner diameter of the through hole 112 smaller than a predetermined diameter, it is possible to suck water droplets or the like from the through hole 112 by capillary action. That is, even in the ejection head excluding the connection path 114 and the pump 116 from the ejection head 100, it is possible to remove water droplets and the like from the nozzle surface 102.

  In the above embodiment, conductive ink is used as the liquid to be ejected, but various liquids can be used. Specifically, for example, it is possible to employ ink capable of printing a resin pattern, dye-based ink, pigment-based ink, and the like. Furthermore, the print medium is not limited to a circuit board, and various print media can be employed. Specifically, for example, a substrate having a chip, paper, or the like can be employed.

  DESCRIPTION OF SYMBOLS 10: Printing apparatus 12: Circuit board (printing medium) 20: Discharge head (droplet discharge head) 22: Stage 30: Head main body 32: Hygroscopic material (porous body) (suction mechanism) 34: Cooling mechanism (cooling apparatus) 36: Nozzle hole 38: Nozzle surface 50: Lipophilic region 52: Liquid repellent region 58: Heater 80: Discharge head (droplet discharge head) 82: Nozzle surface 84: Liquid repellent region 86: Lipophilic region 88: Lipophilic region 90: Liquid repellent area 100: Discharge head (droplet discharge head) 102: Nozzle surface 104: Liquid repellent area 106: Lipophilic area 108: Liquid repellent area 110: Head body 112: Through hole (suction mechanism) 114: Connection path (Suction mechanism) 116: Pump (Suction mechanism) (Pump)

Claims (5)

In a droplet discharge head that discharges droplets to a print medium,
The droplet discharge head is
A head body in which nozzle holes for discharging droplets are formed;
A cooling device for cooling the head body,
The nozzle surface where the nozzle hole of the head body opens,
A liquid repellent region that is formed around the opening of the nozzle hole and has a low affinity with the liquid;
A droplet discharge head comprising: a lyophilic region that is formed so as to surround the liquid repellent region and has a higher affinity than the liquid repellent region. The droplet discharge head is
The droplet discharge head according to claim 1, further comprising a suction mechanism that sucks a liquid that communicates with the lyophilic region and has affinity for the lyophilic region. The suction mechanism is
It has a porous body with many pores formed,
The liquid discharge head according to claim 2, wherein the liquid having affinity for the lyophilic region is sucked into the pores of the porous body. The suction mechanism is
4. The droplet discharge head according to claim 2, further comprising a pump, wherein the liquid that is compatible with the lyophilic region is sucked by the operation of the pump. A stage for supporting the print medium;
A droplet discharge head for discharging droplets to a print medium supported by the stage;
In a printing apparatus comprising: a heater for heating a printing medium supported by the stage;
The droplet discharge head is
A head body in which nozzle holes for discharging droplets are formed;
A cooling device for cooling the head body,
The nozzle surface where the nozzle hole of the head body opens,
A liquid repellent region that is formed around the opening of the nozzle hole and has a low affinity with the liquid;
A printing apparatus comprising: a lyophilic region which is formed so as to surround the liquid repellent region and has a higher affinity than the liquid repellent region.

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