JP2007237474A - Liquid droplet discharge head, method for manufacturing liquid droplet discharge head and image forming apparatus equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet discharge head which can prevent a short of electrode and breakdown of insulation which are caused by dew formation by preventing the peeling of a sealing agent to secure moistureproofness with uniformly applying the sealing agent to a drive element. <P>SOLUTION: The sealing agent 45 is blocked up with a dummy element 44 by pouring the liquid-like sealing agent 45 into the area surrounded with the dummy element 44 and then uniformly filled around the drive element 42. Thereby, the sealing agent 45 is applied uniformly around the drive element 42 and moisture proofness is secured, and then the short of electrode and breakdown of insulation caused by the dew formation can be prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a droplet discharge head including a nozzle for discharging a liquid, a method for manufacturing the droplet discharge head, and an image forming apparatus including the droplet discharge head.

Some inkjet heads (droplet ejection heads) coat a piezoelectric element (driving element) with an epoxy adhesive. (Patent Document 1)
According to this, a plurality of piezoelectric elements (driving elements) bonded and fixed to the substrate are faced downward and dipped into a container filled with an epoxy adhesive (sealing material). Accordingly, the moisture resistance is improved by coating the piezoelectric element (driving element) and the internal electrode of the piezoelectric element (driving element) with an epoxy-based adhesive (sealing material), and the short circuit of the electrode in a high temperature and high humidity environment Prevents dielectric breakdown.
JP 2003-62999 A

  However, in dipping, the coating film thickness is not constant and is not stable. In addition, when an external force is applied to a portion where the film thickness is thin, the coating is expected to be peeled off. When the coating is peeled off, an electrode short circuit or dielectric breakdown occurs.

  In consideration of the above facts, the present invention applies a sealing material uniformly to the drive element to prevent peeling of the sealing material and ensure moisture resistance, thereby preventing electrode short-circuiting and dielectric breakdown due to condensation. An object of the present invention is to provide a liquid droplet ejection head that can be used.

  A droplet discharge head according to a first aspect of the present invention constitutes a part of a pressure chamber filled with a liquid, and displaces a vibration plate that discharges the liquid from a nozzle and a surface of the vibration plate. A plurality of driving elements that are disposed and that displace the diaphragm by applying a voltage; a first outflow prevention wall that is disposed on a surface of the diaphragm and surrounds the plurality of driving elements; And a sealing material which is poured into the inside of the outflow prevention wall and seals the driving element.

  According to the above configuration, when the sealing material is poured into the first outflow prevention wall, the first outflow prevention wall blocks the outflow of the sealing material, and the sealing material is uniformly inside the first outflow prevention wall. The sealing material is uniformly applied to the drive elements. Thereby, it is possible to prevent electrode short-circuiting and dielectric breakdown by preventing peeling of the sealing material and ensuring moisture resistance.

  According to a second aspect of the present invention, there is provided the droplet discharge head according to the first aspect, wherein the first outflow prevention wall is a plurality of non-driven dummy elements that are divided by slits and have the same resonance frequency as the driving element. It is characterized by being configured.

  According to the above configuration, a plurality of dummy elements having the same resonance frequency as that of the drive element are formed by dividing the first outflow prevention wall by the slits. For this reason, the displacement characteristics of the drive elements adjacent to the dummy elements are the same as those of the other drive elements, and the diaphragm can be displaced in the same manner for all the drive elements. Thereby, the discharge of the liquid from a nozzle is stabilized.

  A droplet discharge head according to a third aspect of the present invention is characterized in that, in the second aspect, the flow path resistance of the slit is larger than the flow path resistance between the drive elements.

  According to the above configuration, the sealing material tends to flow out from the slit between the dummy elements depending on the viscosity, but the flow resistance of the slit is larger than the flow resistance between the driving elements, so that it does not leak from the slit. The sealing material is uniformly filled in the area surrounded by the dummy elements. For this reason, the sealing material is not wasted.

  According to a fourth aspect of the present invention, in the liquid droplet ejection head according to the second or third aspect, the second outflow prevention wall for preventing the sealing material from flowing out of the slit is provided around the first outflow prevention wall. It is characterized by that.

  According to the said structure, the outflow of the sealing material from a slit is prevented by the 2nd outflow prevention wall. For this reason, a sealing material with low viscosity can also be used.

  A droplet discharge head according to a fifth aspect of the present invention is characterized in that, in any one of the first to third aspects, the height of the first outflow prevention wall is higher than that of the driving element.

  According to the said structure, since the height of a 1st outflow prevention wall is higher than a drive element, it will not leak outside even if a sealing material is poured more.

  A droplet discharge head according to a sixth aspect of the present invention is the droplet discharge head according to any one of the first to fifth aspects, wherein the first outflow prevention wall is formed of the same material as the driving element. To do.

  According to the above configuration, since the first outflow prevention wall is formed of the same material as that of the drive element, the first outflow prevention wall can be processed within the processing step of the drive element. For this reason, it is not necessary to provide the special process which processes a 1st outflow prevention wall.

  According to a seventh aspect of the present invention, in the liquid droplet ejection head according to the fourth aspect, the first outflow prevention wall and the second outflow prevention wall are formed of the same material as the driving element. And

  According to the above configuration, since the first outflow prevention wall and the second outflow prevention wall are formed of the same material as the drive element, the first outflow prevention wall and the second outflow prevention wall are formed in the processing step of the drive element. Can be processed. For this reason, it is not necessary to provide the special process which processes a 1st outflow prevention wall and a 2nd outflow prevention wall.

  According to an eighth aspect of the present invention, there is provided a liquid head manufacturing method comprising: a first step of sequentially laminating a lower electrode layer, a piezoelectric element layer, and an upper electrode layer on a diaphragm; a lower electrode layer, a piezoelectric element layer; A second step of forming a driving element having a lower electrode and an upper electrode by dividing the laminate of the upper electrode layer into a plurality of pieces, and a dummy element surrounding the driving element; and an electrical connection portion of the upper electrode. A third step of masking with a masking material, a sealing material for sealing the driving element is poured into a region surrounded by the dummy element, a fourth step of sealing the driving element, and the masking material for the upper electrode is removed. And a fifth step of connecting the solder bump and the electrical connection portion of the upper electrode by bringing the substrate provided with the solder bump closer from above.

  According to the manufacturing method, in the first step, the lower electrode layer, the piezoelectric element layer, and the upper electrode layer are sequentially laminated on the diaphragm.

  Next, in the second step, a driving element including the lower electrode and the upper electrode by dividing the stacked body of the lower electrode layer, the piezoelectric element layer, and the upper electrode layer into a plurality of pieces, and a dummy element surrounding the driving element, Form.

  Next, in the third step, the electrical connection portion of the upper electrode is masked with a masking material.

  Next, in a fourth step, a sealing material for sealing the driving element is poured into a region surrounded by the dummy elements, and the driving element is sealed. As a result, the sealing element is uniformly applied to the drive element, so that the moisture resistance of the drive element is ensured, and it is possible to prevent an electrode short-circuit or dielectric breakdown due to condensation.

  Next, in the fifth step, the masking material of the upper electrode is removed, and the substrate on which the solder bump is provided is approached from above to connect the solder bump and the electrical connection portion. That is, since the electrical connection portion of the upper electrode is masked with the masking material, the sealing material is not attached. For this reason, the upper electrode is easily connected to the solder bump.

  An image forming apparatus according to a ninth aspect of the present invention is characterized in that the liquid droplet ejection head according to any one of the first to seventh aspects is provided.

  According to the above configuration, since the droplet discharge head according to any one of claims 1 to 7 is provided in the image forming apparatus, the moisture resistance of the driving element is ensured to prevent the electrode from being short-circuited or broken down. Can be prevented.

  An image forming apparatus according to a tenth aspect of the present invention is provided with a liquid droplet ejection head manufactured by the method for manufacturing a liquid droplet ejection head according to the eighth aspect.

  According to the above configuration, since the image forming apparatus includes the droplet discharge head manufactured by the droplet discharge head manufacturing method according to the eighth aspect, the moisture resistance of the driving element is ensured and the electrode Short circuit and dielectric breakdown can be prevented.

  According to the liquid droplet ejection head of the present invention, the sealing material is uniformly applied to the drive element, thereby preventing the sealing material from peeling off and ensuring moisture resistance, thereby preventing short-circuiting or dielectric breakdown of the electrode due to condensation. Can be prevented.

  A first embodiment of an image forming apparatus employing a droplet discharge head of the present invention will be described with reference to FIGS.

  As shown in FIG. 5, an inkjet recording apparatus 102 as an image forming apparatus includes a carriage 104 on which an inkjet recording head 112 as a droplet discharge head is mounted, and a main that scans the carriage 104 along the main scanning direction M. It has a scanning mechanism 106, a sub-scanning mechanism 108 that transports the recording paper P along the sub-scanning direction S, and a maintenance station 110.

  The ink jet recording head 112 is mounted on the carriage 104 so that the nozzle plate 21 on which the nozzles 10 are formed (see FIG. 1) faces the recording paper P, and is moved in the main scanning direction M by the main scanning mechanism 106. By ejecting ink droplets from 10, an image is recorded on a certain band region BE of the recording paper P. When one movement in the main scanning direction is completed, the recording paper P is conveyed in the sub scanning direction S by the sub scanning mechanism 108, and the carriage 104 moves in the main scanning direction M again to record the band area BE. By repeating such an operation a plurality of times, image recording can be performed over the entire surface of the recording paper P.

  As shown in FIGS. 1 and 3, the inkjet recording head 112 includes nozzles 10 arranged in a matrix, a pressure chamber 14 that communicates with the nozzles 10, and a common ink chamber 20 that supplies ink to the pressure chambers 14. I have.

  A nozzle communication path 12 is provided in the vicinity of the apex on the side of the pressure chamber 14 where the nozzle 10 is provided, and the nozzle 10 and the pressure chamber 14 are communicated by the nozzle communication path 12. On the other hand, the pressure chamber 14 and the common ink chamber 20 are communicated by the thickness direction communication path 18 and the planar direction communication path 16.

  As shown in FIG. 2, the nozzle plate 21, the ink pool plate 22 and the ink pool plate 23 in which the nozzle communication path 12 and the common ink chamber 20 are formed, and the thickness direction communication path 18 of the common ink chamber 20 The through plate 24 in which the nozzle communication path 12 is formed, the ink supply path plate 26 in which the planar communication path 16 is formed, and the pressure chamber plate 28 in which the pressure chamber 14 is formed are stacked in this order. A flow path plate unit 29 is formed.

  Further, the vibration plate 30 is bonded to the upper surface of the pressure chamber plate 28, and the driving element 42 and the dummy element 44 as the first outflow prevention wall are bonded to the upper surface of the vibration plate 30 at a position corresponding to the pressure chamber 14. ing.

  The drive element 42 is a drive unit that is deformed by electrostriction and pressurizes the ink in the pressure chamber 14. Electrodes for applying a voltage to the drive element 42 are formed on the upper and lower surfaces of the drive element 42.

  Next, details of the drive element 42, the dummy element 44, and the sealing material 45 will be described.

  As shown in FIG. 3, the drive elements 42 are arranged in a matrix and are provided for each pressure chamber 14 above the pressure chamber 14 (see FIG. 2) when viewed in plan. Further, dummy elements 44 are arranged in a matrix so as to surround the drive element 42. In the figure, the drive element 42 and the dummy element 44 are illustrated in a substantially rectangular shape, but in actuality, the drive element 42 and the dummy element 44 are processed into a shape that follows the shape of the pressure chamber. On the other hand, the shape of the dummy element 44 is a shape in which a triangular wall portion 44A for reducing the gap between the dummy elements 44 is added to the shape of the drive element 42 in plan view. Since the shape of the dummy element 44 includes the shape of the drive element 42, the resonance frequency of the dummy element 44 and the resonance frequency of the drive element 42 are substantially the same frequency.

  With this configuration, slits 46 are formed between adjacent wall portions 44 </ b> A in adjacent dummy elements 44. The flow path resistance of the slit 46 is larger than the flow path resistance between the drive elements 42.

  As described above, the drive element 42 is provided with the lower electrode 42A having one polarity below the drive element 42, and the upper electrode 42B having the other polarity is provided above the drive element 42. (See FIG. 2). The lower electrode 42A side is bonded to the diaphragm 30, and the upper electrode 42B side is bonded to the circuit board 36 via the solder bumps 34. As a result, a predetermined voltage is applied from the circuit board 36 to the drive element 42 via the solder bump 34, and the drive element 42 is driven to pressurize and depressurize the inside of the pressure chamber 14.

  The dummy element 44 is formed of the same material as the drive element 42 and includes a lower electrode 44B and an upper electrode 44C. The dummy element 44 is processed to the same height as the drive element 42, but the upper electrode 44C and the circuit board 36 are formed. And the dummy element 44 is not driven.

  Further, a sealing material 45 that prevents moisture from adsorbing to the electrodes of the drive element 42 is applied to the drive element 42 surrounded by the dummy elements 44. In this embodiment, a fluorine-based resin having a viscosity of 10 Pa · s is used for the sealing material 45.

  Next, the operation of the ink jet recording head 112 will be described.

  As shown by an arrow Y in FIG. 1B, the ink introduced from the ink tank is filled into the common ink chamber 20, the pressure chamber 14, and the nozzle communication path 12. A predetermined voltage is applied to the drive element 42 from the circuit board 36 through the solder bumps 34 (see FIG. 2) in a state of being filled with ink, whereby the drive element 42 is driven and the pressure chamber 14 is pressurized and depressurized. Ink droplets are ejected from the nozzle 10.

  Here, the dummy element 44 has the same resonance frequency as that of the driving element 42, the dummy elements 44 are arranged in a matrix like the driving element 42, and the sealing material 45 is driven. Since the periphery of the element 42 is uniformly filled, the displacement characteristics of the drive element 42 adjacent to the dummy element 44 are the same as those of the other drive elements 42, and all the drive elements 42 have the diaphragm 30 in the same manner. Can be displaced. Thereby, the discharge of the ink from the nozzle 10 is stabilized.

  Next, the manufacturing procedure of the inkjet recording head 112 will be described with reference to FIG.

  First, as shown in FIG. 4A, a lower electrode layer, a piezoelectric element layer, and an upper electrode layer are sequentially laminated on the diaphragm 30 by sputtering.

  Next, as shown in FIG. 4B, the lower electrode layer, the piezoelectric element layer, and the upper electrode layer are patterned and etched to be processed into a driving element 42 and a dummy element 44 surrounding the driving element 42. . For this reason, the heights of the drive element 42 and the dummy element 44 are the same, and in this embodiment, the height is 40 μm. Thereby, the dummy element 44 and the drive element 42 can be processed in the same process.

  Next, as shown in FIG. 4C, the electrical connection portion on the upper surface of the upper electrode 42B is masked with a masking material 48 in order to prevent the sealing material 45 from adhering.

  Next, as shown in FIGS. 4D and 3, the liquid sealing material 45 is poured into the area surrounded by the dummy elements 44. Since the poured sealing material 45 is blocked by the dummy element 44 and is uniformly filled around the driving element 42, the sealing material 45 is uniformly applied around the driving element 42. Further, since the flow path resistance of the slit 46 shown in FIG. 3 is larger than the flow path resistance between the drive elements 42, the sealing material 45 does not leak from the slit 46. After the filling of the sealing material 45 is completed, the sealing material 45 is left in a high-temperature bath at 120 ° C. for 1 hour or longer in this state to cure the sealing material 45 in a gel state. Since the sealing material 45 is cured in a gel state, the sealing material 45 has little influence on the displacement of the drive element 42.

  In the present embodiment, the opening size of the slit 46 shown in FIG. 3 is set to 10 μm, which is 1/3 of the distance between the drive elements 42.

  Next, as shown in FIG. 4E, the masking material 48 is removed, the circuit board 36 provided with the solder bumps 34 is approached from above, the circuit board 36 is pressurized, and the solder bumps 34 and the upper electrodes 42B is connected. At the time of connection, heaters are disposed on the upper and lower surfaces, and the solder bumps 34 are melted. Since the electrical connection portion of the upper electrode 42B is masked by the masking material 48, the sealing material is not attached. Therefore, the upper electrode 42B is securely connected to the solder bump 34.

  Through the above steps, the ink jet recording head 112 shown in FIG. By this manufacturing method, the sealing material 45 is uniformly filled around the driving element 42, so that the sealing material 45 is uniformly applied to the driving element 42. Accordingly, it is possible to prevent the electrode from being short-circuited or dielectric breakdown due to condensation by preventing the sealing material 45 from peeling off and ensuring moisture resistance.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the above embodiment, the sealing material 45 is a one-component, fluorine-based resin that is cured in a gel-like manner to ensure moisture resistance. Instead, a gel that uses a two-component resin or the like is used. It may be cured to form a moisture-proof property.

  In this embodiment, the image forming apparatus including the scanning head has been described as an example. However, a fixed head including an ink discharge mechanism longer than the width of the recording medium can be applied.

  Next, a second embodiment of the image forming apparatus employing the droplet discharge head of the present invention will be described with reference to FIGS.

  In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIGS. 6 and 7, in this embodiment, unlike the first embodiment, in order to prevent the sealing material 45 from flowing out of the slit 46, a second outflow prevention wall 60 is provided on the outer periphery of the slit 46. Is provided.

  Specifically, the second outflow prevention wall 60 is formed of the same material as that of the driving element 42 as in the dummy element 44 and is processed in the same process. The second outflow prevention wall 60 is a small block and is provided 10 μm away from the dummy element 44. As a result, the second outflow prevention wall 60 prevents the sealing material 45 from flowing out of the slit 46 even when a low viscosity sealing material 45 (for example, 2 Pa · s) is poured into the dummy element 44.

  Next, a third embodiment of the image forming apparatus in which the droplet discharge head of the present invention is employed will be described with reference to FIGS.

  In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIGS. 8 and 9, in this embodiment, the dummy element and the driving element are not at the same height as in the first embodiment, and instead, the height of the dummy element 70 is changed. Is higher than the height of the drive element 42.

  Specifically, a high wall resin layer 70 </ b> A is formed on the upper portion of the dummy element 70, and the height of the high wall resin layer 70 </ b> A is a difference from the drive element 42. In the present embodiment, the height of the driving element 42 is 40 μm, and the height of the dummy element 70 is set to 80 μm so as not to be higher than the upper surface of the circuit board 36. Thus, even if a large amount of the sealing material 45 is poured, it does not leak outside.

  In addition, the upper surface of the upper electrode 42 </ b> A can be uniformly sealed with the sealing material 45.

FIG. 2A is a perspective view of a droplet discharge head according to the first embodiment of the present invention. (B) It is an expansion perspective view of the droplet discharge head concerning a 1st embodiment of the present invention. FIG. 3 is a cross-sectional view of a drive element portion of the droplet discharge head according to the first embodiment of the present invention. FIG. 3 is a plan view showing that the drive elements and dummy elements of the droplet discharge head according to the first embodiment of the present invention are arranged in a matrix. FIG. 5A is a cross-sectional view illustrating a manufacturing procedure of the droplet discharge head according to the first embodiment of the present invention, and illustrates a state in which a lower electrode layer, a drive element film, and an upper electrode layer are stacked on a vibration plate. (B) A manufacturing procedure of the droplet discharge head according to the first embodiment of the present invention is shown, and it is shown that the driving element and the dummy element are formed by etching the lower electrode layer, the driving element film, and the upper electrode layer. It is sectional drawing. (C) It is sectional drawing which showed the manufacturing procedure of the droplet discharge head which concerns on 1st Embodiment of this invention, and masked the upper surface of an upper electrode with a masking material. (D) It is sectional drawing which showed the manufacturing procedure of the droplet discharge head which concerns on 1st Embodiment of this invention, and showed the state after pouring a sealing material in a diaphragm. (E) It is sectional drawing which showed the manufacturing procedure of the droplet discharge head which concerns on 1st Embodiment of this invention, and showed the state which makes a circuit board. FIG. 6F is a cross-sectional view illustrating the manufacturing procedure of the droplet discharge head according to the first embodiment of the present invention, after the droplet discharge head is completed. 1 is a perspective view showing an image forming apparatus according to a first embodiment of the present invention. It is a perspective view of the droplet discharge head concerning a 2nd embodiment of the present invention. It is a top view which shows the drive element and dummy element of the droplet discharge head which concern on 2nd Embodiment of this invention arrange | positioned at matrix form. It is a perspective view of the droplet discharge head concerning a 3rd embodiment of the present invention. It is sectional drawing of the droplet discharge head which concerns on 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Nozzle 14 Pressure chamber 30 Diaphragm 42 Drive element 44 Dummy element 45 Sealing material 46 Slit 60 Second outflow prevention wall 70 Dummy element 102 Inkjet recording apparatus (image forming apparatus)
112 Inkjet recording head (droplet ejection head)

Claims (10)

A vibration plate that constitutes a part of the pressure chamber filled with the liquid and discharges the liquid from the nozzle by being displaced;
A plurality of driving elements disposed on the surface of the diaphragm and displacing the diaphragm by applying a voltage;
A first outflow prevention wall disposed on the surface of the diaphragm and surrounding the plurality of drive elements;
A sealing material which is poured into the first outflow prevention wall and seals the driving element;
A droplet discharge head characterized by comprising:   2. The droplet discharge head according to claim 1, wherein the first outflow prevention wall includes a plurality of non-driven dummy elements that are divided by a slit and have the same resonance frequency as the drive element.   The droplet discharge head according to claim 2, wherein a flow path resistance of the slit is larger than a flow path resistance between the drive elements.   4. The droplet discharge head according to claim 2, wherein a second outflow prevention wall for preventing the sealing material from flowing out of the slit is provided around the first outflow prevention wall.   4. The droplet discharge head according to claim 1, wherein a height of the first outflow prevention wall is higher than that of the driving element. 5.   6. The droplet discharge head according to claim 1, wherein the first outflow prevention wall is formed of the same material as that of the driving element.   5. The droplet discharge head according to claim 4, wherein the first outflow prevention wall and the second outflow prevention wall are formed of the same material as the driving element. A first step of sequentially laminating a lower electrode layer, a piezoelectric element layer, and an upper electrode layer on the diaphragm;
A second step of forming a driving element including the lower electrode and the upper electrode by dividing the laminate of the lower electrode layer, the piezoelectric element layer, and the upper electrode layer into a plurality of pieces, and a dummy element surrounding the driving element;
A third step of masking the electrical connection portion of the upper electrode with a masking material;
Pouring a sealing material for sealing the driving element into a region surrounded by the dummy element, and sealing the driving element;
A fifth step of removing the masking material of the upper electrode, bringing the substrate on which the solder bump is provided from above, and connecting the electrical connection between the solder bump and the upper electrode;
A method of manufacturing a droplet discharge head, comprising:   An image forming apparatus comprising the liquid droplet ejection head according to claim 1.   An image forming apparatus, comprising: a droplet discharge head manufactured by the method of manufacturing a droplet discharge head according to claim 8.

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