JP4121922B2 - Electrostatic actuator, droplet ejection head, droplet ejection apparatus, and inkjet recording apparatus - Google Patents

Description

  The present invention relates to an electrostatic actuator, a droplet discharge head using the electrostatic actuator, a droplet discharge device using the droplet discharge head, and an ink jet recording apparatus.

  As with other products, ensuring the durability of electrostatic actuators is the most important item, and without this, there is no practical application. There are several reasons for reducing the durability of the electrostatic actuator. A problem in the case of adopting a driving method in which the counter electrode surface is brought into contact especially during driving will be described.

  FIG. 10 is a cross-sectional view showing the structure of a conventional electrostatic actuator. 10A, the electrostatic actuator has a variable electrode 10 and a fixed electrode 20, and is operated by residual charges generated in the insulating films 16 and 24 formed on the conductive layers 17 and 25 of both electrodes. Defects occur. This includes sticking in which the variable electrode 10 is stuck to the fixed electrode 20 due to moisture, atomic force, and the like, and damage to the insulating films 16 and 24 caused by driving.

  To solve the above problem, a structure in which the convex structure 40 is formed on the variable electrode 10 or the fixed electrode 20 is shown in FIGS. With this structure, a configuration in which the variable electrode 10 and the fixed electrode 20 are brought into contact only with the convex structure 40 to reduce the contact area and eliminate residual charges, sticking, and the like can be considered, and many examples are disclosed. . Among them, the effectiveness of the method of improving the durability by preventing positive voltage from being positively applied to the contact portion on the convex structure 40 and the facing surface thereof has been obtained.

Prior art related to the present invention will be described.
JP-A-11-170506 JP 11-291487 A JP-A-2001-260346 JP-A-2001-322273

  In Patent Document 1, a convex structure is provided on the fixed electrode side in order to prevent oxide film damage and electrical short circuit due to contact between the diaphragm (variable electrode) and the fixed electrode, and the diaphragm side and the electrode side are convex portions. It is configured to contact only at. At this time, no conductive material is formed on the contact portion on the fixed electrode side.

  Patent Document 2 adopts a configuration in which an electrodeless portion where no conductive material is formed is provided on one of a first electrode (variable electrode) or a second electrode (fixed electrode).

  Patent Document 3 aims to suppress the generation of residual charges due to the contact between the variable electrode and the fixed electrode. The fixed electrode is divided, and the portion where the variable electrode and the fixed electrode are in contact has the same potential as the variable electrode. The structure which becomes becomes.

  In Patent Document 4, a residual charge is generated on the insulating film when the diaphragm (variable electrode) on which the insulating film is formed and the fixed electrode are in contact with each other, but the object is to suppress the generation of the residual charge. . For this reason, the convex part is provided in the diaphragm side, and the device which makes the part which opposes the convex part of a fixed electrode electrically float with a slit is made | formed.

  Although the prior art has been described above, in most cases, it is the fixed electrode side that has a portion electrically disconnected from the electrode. However, depending on the use, configuration, and process of the head, there may be a case where a portion to which the applied potential is not applied is provided on the variable electrode (diaphragm) side.

  Further, it has been found from the evaluation results of the present applicant that the effect on durability cannot be obtained depending on the method of forming the portion to which the applied potential is not applied. For example, Patent Document 2 adopts a method in which an electrode material is not formed on one of the contact portions, but it is inappropriate for improving durability for the reason described later.

  On the other hand, electrostatic actuators are becoming increasingly miniaturized and diversified, and this trend will not change in the future. In the ink jet head, high integration of nozzles is inevitable in the future.

  In the inkjet head, when the integration degree of the electrostatic actuator is increased, the short side width of the variable electrode is shortened. However, on the other hand, the ejected ink volume must be secured to some extent. Therefore, the short side width of the variable electrode is shortened, but the displacement amount of the variable electrode needs to be increased. In addition, from the viewpoint of ejecting droplets, the variable electrode needs to have a certain degree of rigidity. In conclusion, if the integration degree is increased while maintaining the ability to eject droplets, the electrostatic actuator The drive voltage of this must be high.

  In general, an electrostatic ink jet head has a configuration in which one of a variable electrode and a fixed electrode is electrically common to all electrostatic actuators, and a potential for each electrostatic actuator is applied to the other electrode. However, when a high voltage is used to drive the electrostatic actuator, the driver cost is inevitably high. Therefore, in order to prevent an increase in cost, an inkjet head with highly integrated nozzles has a different sign for both electrodes at the same timing. It is also necessary to study a method for driving the electrostatic actuator so that the total potential becomes a high voltage.

  In an electrostatic actuator, at least one of the variable electrodes is often a laminated film of two or more layers because of the requirements of the characteristics of the electrostatic actuator, and usually each film has an internal stress. In order to electrically cut off a part of the electrode, a method in which no electrode material is formed in the part is the simplest, and this method is also employed in the above-described prior art. FIG. 11 is a cross-sectional view showing a three-layer structure of a conventional electrostatic actuator.

  As shown in FIG. 11, since the variable electrode is a laminated thin film, for example, the three-layer structure variable electrode 10 including the insulating layer 16, the conductive layer 17, and the insulating layer 18 shown in FIGS. 11 (a) and 11 (b). In this case, by not forming the conductive material only on the convex structure 40, the portion has a two-layer structure, and the balance of internal stress differs greatly from the other portions. Here, the difference between FIGS. 11A and 11B varies depending on how the convex structure 40 is formed in the process. As a result, as shown in FIG. 11C, the variable electrode 10 is formed in a state of having an irregular large deformation that is not desired around the convex structure 40 where no electrode material is formed.

  In some cases, this deformation is very large and is larger than the height of the convex structure 40. Originally, the contact between the opposing electrodes needs to be performed only at the convex structure 40 and its opposing portion for the reason described above, but this irregular deformation causes contact at other than the convex structure 40 and its opposing portion. Does not lead to improved durability. Of course, there is no problem as long as the height of the convex structure 40 can be made sufficiently high, but the electrostatic force is proportional to the square of the applied voltage, but is inversely proportional to the square of the distance between the opposing electrodes, so that the distance between the electrodes is increased. The height of the convex structure 40 that leads to that cannot be increased without limit.

  Further, since the return force of the variable electrode 10 when the applied voltage is turned off after applying the voltage to bring the opposed electrodes close to each other is roughly inversely proportional to the distance between the opposed electrodes before the applied voltage is turned off. Is used as an inkjet head, an electrostatic actuator having a weak ink ejection force if the convex structure 40 is high, the height of the convex structure 40 needs to be as low as possible.

  Here, the variable electrode is deformed as shown in FIG. 11C due to the internal stress. However, depending on the laminated structure of the layers having the internal stress, the deformation of the variable electrode is opposite to that in FIG. 11C. It may be. At this time, the gap becomes larger than the specification, and the drive voltage increases greatly. Therefore, such deformation is not preferable from the viewpoint of function.

  The present invention has been made in view of the above problems, and an electrostatic actuator having greatly improved durability, a droplet discharge head using the electrostatic actuator, and a droplet discharge using the droplet discharge head. An object is to provide an apparatus and an ink jet recording apparatus.

  In order to achieve the above object, the invention according to claim 1 is characterized in that a pair of counter electrodes, at least one of which is variable, and a convex structure is provided on the opposing surface of at least one of the electrodes, and a convex structure portion or convex A part of the variable electrode corresponding to the opposite part of the structure is an electrostatic actuator which is electrically separated, and the electrical separation is formed by forming a slit in the conductive layer of the variable electrode and projected onto the electrode surface. The inner peripheral shape of the slit is the same as the convex shape projected on the electrode surface or includes a convex shape.

  The invention according to claim 2 is an electrostatic actuator in which a convex structure is provided on a facing surface of at least one of the pair of counter electrodes, at least one of which is variable, the convex structure portion and the facing portion Are electrically separated from each electrode, and at least the variable electrode is electrically separated by forming a slit in the conductive layer, and the inner peripheral shape of the slit projected onto the electrode surface is projected onto the electrode surface. It is the same as the convex shape to be made, or includes a convex shape.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the convex structure includes a position where the variable electrode is most easily displaced, and when the position where the variable electrode is most easily displaced is a line shape, The edges of the convex structure are substantially orthogonal and are formed in an island shape on at least one of the electrodes.

  According to a fourth aspect of the present invention, there is provided a nozzle, a liquid chamber communicating with the nozzle, a variable electrode, a fixed electrode provided outside the liquid chamber so as to face the variable electrode, and a convex structure on a facing surface of at least one of the electrodes. The portion corresponding to the convex structure portion of the variable electrode or the opposite portion of the convex structure is electrically separated, and the variable electrode is displaced by applying a voltage between the variable electrode and the fixed electrode. A droplet discharge head having a plurality of electrostatic actuators for discharging droplets from a nozzle by a mechanical force generated in the variable electrode, wherein electrical separation is performed by forming a slit in the conductive layer of the variable electrode; and The inner peripheral shape of the slit projected onto the electrode surface is the same as or includes the convex shape projected onto the electrode surface.

  The invention described in claim 5 includes a nozzle, a liquid chamber communicating with the nozzle, a variable electrode, a fixed electrode provided outside the liquid chamber so as to face the variable electrode, and a convex structure on a facing surface of at least one of the electrodes. Droplet discharge that has a plurality of electrostatic actuators that displace the variable electrode by applying a voltage between the variable electrode and the fixed electrode, and discharge the droplet from the nozzle by the mechanical force generated at the variable electrode. The head has a convex structure portion and an opposing portion thereof electrically separated from each electrode, and at least the variable electrode is electrically separated by forming a slit in the conductive layer, and the electrode surface The inner peripheral shape of the slit projected onto the electrode is the same as the convex shape projected on the electrode surface or includes a convex shape.

  The invention according to claim 6 is the invention according to claim 4 or 5, wherein the convex structure includes a position where the variable electrode is most easily displaced, and when the position where the variable electrode is most easily displaced is a line, The edges of the convex structure are substantially orthogonal and are formed in an island shape on at least one of the electrodes.

  The invention described in claim 7 is a droplet discharge device configured by using the droplet discharge head according to any one of claims 4 to 6.

  An eighth aspect of the invention is an ink jet recording apparatus configured using the liquid droplet ejection head according to any one of the fourth to sixth aspects.

  As a method of preventing the applied potential from being applied to the convex portion of the variable electrode or the convex facing portion of the variable electrode that faces the convex portion formed on the counter electrode, it is variable by forming a slit in the conductive layer of the electrode. It is possible to provide an electrostatic actuator that can minimize the balance of internal stress balance around the convex portion or convex facing portion of the electrode, prevent deformation of the variable electrode, and have improved durability. Furthermore, by using this electrostatic actuator, it is possible to provide a droplet discharge head, a droplet discharge device, and an ink jet recording apparatus with improved durability.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the embodiment of the present invention, parts having functions similar to those of the conventional example are described with the same reference numerals.

  FIG. 1 is a structural diagram showing a part of the structure of an electrostatic actuator in an embodiment of the present invention. As shown in FIGS. 1A and 1B, an applied potential is not applied to the convex portion of the variable electrode 10 or the convex opposing portion of the variable electrode 10 that faces the convex portion formed on the counter electrode. As a method for this, it has been found that the method of inserting the slit 42 in the conductive layer 17 of the electrode is extremely effective. By forming such a slit 42, it is possible to minimize the balance of internal stress balance around the convex portion or convex opposing portion of the variable electrode 10, and as a result, prevent deformation of the variable electrode 10 as a result, An electrostatic actuator having the desired functional properties can be obtained. In FIG. 1, 16 and 18 are insulating films.

  At this time, it is preferable that an insulating material is embedded in the slit 42. Further, if the conductive layer 17 is a material having a compressive internal stress (PolySi or the like), an insulating material (SiO 2 or the like) having a compressive internal stress is preferably embedded, and the conductive layer 17 is a material having a tensile internal stress. For example, an insulating material having a tensile internal stress is preferably embedded.

  Thus, in an electrostatic actuator having a convex structure on at least one of the electrodes, by providing a slit for separating the electrode at the convex portion or convex opposing portion of the variable electrode 10, it is possible to effectively prevent deformation due to internal stress. I can do it.

  (C) and (d) of FIG. 1 show an example of the arrangement relationship when the convex structure 40 and the slit 42 are projected onto the electrode surface. A sectional view and a lower view around the convex structure are shown. In FIGS. 1C and 1D, the size of the slit 42 is different. The important point is that the outer peripheral shape of the slit 42 must be the same as the shape of the convex structure 40 or a shape that completely includes the shape of the convex structure 40. Further, the convex height described in the present invention means tt in FIG. In FIG. 1, the conductive material portion 41 will be described later.

  Here, in FIG. 1, an insulating film is formed on the entire variable electrode (fixed electrode), but the presence or absence of an insulating film other than the contact portion is not limited in the present invention. In the present invention, the presence or absence of the insulating film in the contact portion is not limited as long as the convex portion which is the contact portion and the convex opposed portion have the same potential. Further, when forming the laminated plate, the laminated structure of the convex peripheral portion is slightly changed in FIGS. 1A and 1B due to the arrangement of the film and etching, as shown in the figure. It doesn't matter.

  FIG. 2 is a cross-sectional view showing the basic structure of the electrostatic actuator in the embodiment of the present invention. With reference to FIG. 2, the manufacturing process of the electrostatic actuator in embodiment of this invention is demonstrated.

  A thermal oxide film 23 is formed on a Si substrate, PolySi 22 serving as a conductive layer of the fixed electrode 20 and HTO 21 serving as an insulating film are sequentially stacked thereon, and PolySi is stacked as a sacrificial layer serving as a gap space between the opposing electrodes. HTO11 which is an insulating film of the variable electrode 10, PolySi12 which is a conductive layer, and 13 which is Si3N4 having a tensile internal stress are sequentially laminated, and further, HTO14 is formed, PolySi of the sacrificial layer is removed, and finally A polyimide film 15 as a liquid contact layer was laminated to form an electrostatic actuator.

  Further, a plurality of electrostatic actuators are integrated to form an electrostatic head (inkjet head: droplet discharge head). This droplet discharge head includes a plurality of electrostatic actuators that displace the variable electrode by applying a voltage between the variable electrode and the fixed electrode, and discharge the droplet from the nozzle by the mechanical force generated in the variable electrode. It is configured.

  At this time, the convex structure 40 is composed of HTO 11 formed as an insulating film on the variable electrode side. The fixed electrode 20 has a configuration in which the potential of each electrostatic actuator is applied so that the potential of the variable electrode 10 is the same for all the electrostatic actuators. Further, the short side width of the variable electrode = 60 μm, the long side length = 500 μm, AirGap = 0.4 μm, and the convex height = tt = 0.1 μm.

  FIG. 3 is a cross-sectional view showing the structure of the electrostatic actuator in the embodiment of the present invention. The electrostatic actuator shown in FIG. 3 is a prototype. FIGS. 3A, 3B, and 3C show stacked configurations A, B, and C of the prototype electrostatic actuator, respectively.

  In the laminated configuration A shown in FIG. 3A, the convex conductive material portion 41 is electrically separated by a slit in the variable electrode. In the stacked configuration B shown in FIG. 3B, the conductive material is not formed on the convex portion of the variable electrode. In the stacked configuration C shown in FIG. 3C, the conductive material portions 41 and 43 of the convex portion of the variable electrode and the convex facing portion of the fixed electrode are electrically separated by a slit. FIGS. 3A to 3C show the cross-sectional configuration of the field in which the convex structure is formed in one row in the long side direction of the variable electrode, but the basic configuration is the same in the case of two rows. FIGS. 3D and 3E are plan views of the electrostatic actuator in which the conductive layer cuts off the potential by the slit 42.

  FIG. 4 is a plan view showing the configuration and arrangement of the convex structure 40 in the variable electrode plane in the electrostatic actuator according to the embodiment of the present invention. In FIG. 4A, the convex structures 40 are arranged in two rows in the long side direction, and in FIG. 4B, the convex structures 40 are arranged in one row in the long side direction. Each specification ta, tb, tc, td is described in the following Tables 2, 4, 6, and 8.

  The durability of the electrostatic actuator was judged based on whether or not the variable electrodes 10 were removed from the electrostatic actuator after the durability test and the HTOs 11 and 21 formed on the variable electrode 10 and the fixed electrode 20 were damaged. In addition, although the endurance test in the embodiment of the present invention is not performed while discharging droplets, the result of the endurance test is directly connected to the result of the endurance test performed while discharging droplets. Therefore, the durability of the electrostatic actuator in the droplet discharge head can also be determined directly from this embodiment. The production method and the evaluation method described above are common in the first to fourth embodiments of the present invention.

  In Tables 2, 4, 6, and 8, the electrostatic actuator is described as an actuator. Also, configurations A, B, and C in the table indicate the stacked configuration of FIG. 3, and configurations a and b in the convex arrangement indicate the arrangements (a) and (b) of the convex structure 40 of FIG.

  First, in the first example, electrostatic actuators A and B were prototyped, subjected to an endurance test, and compared for durability. FIG. 5 is an applied voltage diagram showing applied voltages to the variable electrode and the fixed electrode in the durability test of the electrostatic actuator according to the embodiment of the present invention. In FIG. 5 (a), a + 72V rectangular wave and a -72V rectangular wave were alternately applied to the variable electrode, and a durability test was performed with the fixed electrode as GND. Setting the head temperature to 39 ° C. has the meaning of an accelerated test. Table 1 shows the driving conditions of this durability test.

  Table 2 shows the configuration of the electrostatic actuator and the durability test results. As shown in Table 2, the durability of the electrostatic actuator B is low because the conductive material was not formed on the convex portion, so that the diaphragm was greatly deformed around the convex portion, and the convex portion became the fixed electrode. This is because the portion of the variable electrode other than the convex also comes into contact with the fixed electrode. The contact portion other than the convex portion is a normal electrode portion, and the applied voltage is applied to the oxide film as it is, causing damage to the oxide film in this portion, resulting in malfunction of the electrostatic actuator.

  Further, if the slit width for potential separation of the variable electrode is excessively widened, the balance of internal stress is greatly disturbed around the convex portion, which leads to deformation of the variable electrode. Therefore, it is necessary to make the slit width as narrow as possible. Although the lower limit depends on the performance of the apparatus for forming the slit width, it is possible to manufacture with a width of 0.1 μm, and it seems that this level is the lower limit at present.

  On the other hand, it is considered that the upper limit of the slit width depends on the scale of the electrostatic actuator, the use range of the driving voltage, and the like. Considering the cross section of the variable electrode 10, if the width of the slit at which the internal stress is not uniform is wider than the thickness of the variable electrode 10, the influence of the internal stress on the deformation of the variable electrode is likely to increase.

  Next, a second embodiment of the present invention will be described. In the second example, electrostatic actuators F, G, and H were prototyped, subjected to a durability test, and the durability was compared. Each film thickness configuration of the prototype laminate plate of the electrostatic actuator is variable electrode HTO = 0.15 μm, PolySi = 0.1 μm, Si3N4 = 0.13 μm, HTO = 0.6 μm, polyimide film = 1.0 μm. .

  Here, as in the first embodiment, as shown in FIG. 5 (a), a + 72V rectangular wave and a -72V rectangular wave were alternately applied to the variable electrode, and a durability test was performed with the fixed electrode as GND. . Table 2 shows the driving conditions of the durability test. The driving conditions in Table 2 are the same as in Table 1.

  Table 4 shows the configuration of the electrostatic actuator and the durability test results. The prototyped variable electrode has a thickness of 1.98 μm. As shown in Table 4, damage to the oxide film is observed only in the electrostatic actuator H whose slit width is slightly wider than the variable electrode thickness. This is because, since the slit is wide, the balance of internal stress greatly changes around the slit, and the resulting variable electrode deformation is large, so that when the electrostatic actuator is driven, contact between both electrodes other than the convex portion occurs. Good results were obtained with an electrostatic actuator having a slit width of 0.5 or 1.0 μm or less with a variable electrode thickness.

  Further, in FIGS. 1C and 1D, even if the outer peripheral shapes of the convex structure 40 and the slit 42 are the same, an ideal function can be obtained, but the specification variation in the manufacturing process, the electrostatic actuator In consideration of reliability, the slits 42 are preferably arranged so as to include the convex structure 40 at a certain interval. On the other hand, the larger the outer peripheral shape of the slit 42, the smaller the electrode area to which the voltage is applied, which is not preferable. Empirically, the interval between the outer peripheral shapes of the convex structure 40 and the slit 42 is preferably greater than 0 μm and not greater than 3 μm, and more preferably not less than 0.2 μm and not greater than 1.5 μm.

  As described above, since the electrostatic actuator will continue to be miniaturized in the future, the electrostatic actuator is configured so that the total applied voltage is increased by applying a non-zero potential to both electrodes depending on the application. Need arises. In such a case, the durability can be improved by providing a configuration in which the convex portions and the convex opposing portions of the opposing electrodes are electrically separated from the respective electrodes. At this time, at least the potential separation on the variable electrode side is preferably performed by a slit.

  Further, it is more preferable that the conductive material portions of the convex portions and the convex opposing portions of both electrodes have the same potential, but it is sufficient that both the conductive material portions of the convex portions and the convex opposing portions are electrically floated. An effect is obtained.

  Next, a third embodiment of the present invention will be described. In the third example, electrostatic actuators C, D, and E were prototyped, subjected to a durability test, and the durability was compared. As shown in FIG. 3D, the electrostatic actuator D is obtained by electrically floating the conductive material portions 41 and 43 of the convex portion and the convex opposed portion by the slit 42, and the electrostatic actuator E is shown in FIG. As shown in e), the convex portion and the convex opposed portion are electrically drawn out to the partition wall of the electrostatic actuator by electrically connecting the conductive material portions 41 and 43 through the slit 42, and form part of the partition wall (not shown). Potential and GND.

  In the third embodiment, the driving conditions are different from those in the first and second embodiments. As shown in FIG. 5B, a + 40V rectangular wave and a −40V rectangular wave are alternately applied to the variable electrode, and a −32V rectangular wave and a + 32V rectangular wave are alternately applied to one fixed electrode. Then, driving was performed and a durability test was performed. The driving conditions in the third example are shown in Table 5.

  Table 6 shows the configuration of the electrostatic actuator and the durability test results. The reason why the durability of the electrostatic actuator C is low is that a voltage of 0 V or more and 40 V or less is applied to the oxide film of the projecting portion and the projecting opposing portion which are contact portions. On the other hand, even when the electrostatic actuators D and E were driven 5E + 9 times or more, the oxide film was not damaged, and a difference in durability could not be confirmed.

  Even with the above-described configuration, sufficient durability can be obtained depending on the use of the electrostatic actuator. However, when further durability is required, a design that also considers the arrangement of the convex structure is required.

  That is, the convex structure is arranged so as to include a position where the variable electrode is most easily displaced when the electrostatic actuator is driven. Further, when the position that is most easily displaced is in a line shape, the line and the edge of the convex structure are substantially orthogonal to each other and are formed in an island shape on at least one of the electrodes. Here, the position that is most easily displaced is the center of the disk if it is a peripherally fixed disk, and the center line in the short side direction if it is a rectangular plate that is fixed on four sides. That is, it is the center line in FIG.

  FIG. 6 is a layout view of the convex structure 40 of the electrostatic actuator according to the embodiment of the present invention. As shown in FIG. 6, if the variable electrode is a disk fixed at the periphery, the convex structure 40 should be arranged as shown in FIG. 6A, for example, and should not be arranged as shown in FIG. 6B. Furthermore, it is considered optimal to provide a circular convex structure at the center of the disc. Further, if the displacement plate is a rectangular plate with four sides fixed, the convex structure 40 should not be arranged as shown in FIG. 4A, for example, as shown in FIG. In FIG. 4B, the position that is most likely to be displaced is a line, and the line and the convex edge are arranged substantially orthogonally. Here, since the electrostatic energy cannot be stored by adopting a configuration in which no voltage is applied to the convex portion and the convex opposed portion, if the variable electrode is a rectangular plate, it is not a rod shape in the long side direction but an island shape ( It should be formed in FIG.

  FIG. 7 is a cross-sectional view when the variable electrode of the electrostatic actuator according to the embodiment of the present invention contacts the fixed electrode. The effect of the above configuration will be described with reference to FIG. FIG. 7 shows a configuration in which the convex structures 40 are arranged in two rows in the long side direction of the variable electrode 10 as shown in FIG. In this configuration, when the electrostatic actuator is driven, the edge of the convex structure 40 comes into contact with the electrode with an acute angle, so that the insulating film 21 in this portion and the convex itself are easily damaged, and the durability is low. This is not related to the fact that the convex portion is not electrically separated.

  Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, as shown in Table 7, the number of times of driving is different from that in the first and second embodiments. In addition, as shown in FIG. 3D, the prototype electrostatic actuators I and J are electrically floated by the slits 42 in the conductive material portions 41 and 43 of the convex portion and the convex opposed portion. Is.

  Table 8 shows the configurations and durability test results of the electrostatic actuators I and J. As shown in Table 8, the durability of the electrostatic actuator shown in FIG. 4B in which the protrusions are formed in one row in the long side direction is greatly improved.

  Next, an example in which the electrostatic actuator of the present invention is used in an ink jet recording apparatus will be described. FIG. 8 is a perspective view of an ink jet recording apparatus using the electrostatic actuator of the present invention. FIG. 9 is a cross-sectional view of an ink jet recording apparatus using the electrostatic actuator of the present invention. The ink jet recording apparatus of the present invention will be described with reference to FIGS.

  This ink jet recording apparatus drives and controls a recording head which is a droplet discharge head composed of a carriage movable in the main scanning direction inside the recording apparatus main body 81, an electrostatic actuator of the present invention mounted on the carriage, and the recording head. A paper feed cassette that accommodates a printing mechanism 82 composed of a drive device, an ink cartridge that supplies ink to the recording head, and the like, and can stack a large number of sheets 83 from the front side in the lower portion of the recording apparatus main body 81. (Alternatively, it may be a paper feed tray) 84 can be detachably mounted, and the manual feed tray 85 for manually feeding the paper 83 can be opened, and the paper feed cassette 84 or the manual feed tray 85 can be opened. A paper discharge tray mounted on the rear side after taking in the paper 83 fed from the printer and recording a required image by the printing mechanism 82 6 to discharging.

  At the time of recording, the recording head 94 is driven according to the image signal while moving the carriage 93, thereby ejecting ink onto the stopped sheet 83 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 83 has reached the recording area, the recording operation is terminated and the paper 83 is discharged.

  Thus, the ink jet recording apparatus is equipped with the ink jet head embodying the present invention, and an inexpensive ink jet recording apparatus having high durability and reliability can be provided.

  Furthermore, by using the above-described droplet discharge head, it is possible to provide a droplet discharge device that discharges not only ink but also other droplets.

  Although the embodiment of the present invention has been described in detail as described above, the above embodiment is an example of a preferred embodiment of the present invention, and is not limited thereto. Various modifications can be made without departing from the scope.

It is a structure figure showing a part of structure of an electrostatic actuator in an embodiment of the present invention. It is sectional drawing which shows the basic structure of the electrostatic actuator in embodiment of this invention. It is sectional drawing which shows the structure of the electrostatic actuator in embodiment of this invention. It is a top view which shows the structure and arrangement | positioning of a convex structure in the variable electrode surface in the electrostatic actuator of embodiment of this invention. It is an applied voltage figure which shows the applied voltage to the variable electrode and fixed electrode in the durability test of the electrostatic actuator of embodiment of this invention. It is an arrangement plan of the convex structure of the electrostatic actuator of the embodiment of the present invention. It is sectional drawing when the variable electrode of the electrostatic actuator of embodiment of this invention contact | abuts to the fixed electrode. 1 is a perspective view of an ink jet recording apparatus using an electrostatic actuator of the present invention. It is sectional drawing of the inkjet recording device using the electrostatic actuator of this invention. It is sectional drawing which shows the structure of the conventional electrostatic actuator. It is sectional drawing which shows the three-layer structure of the conventional electrostatic actuator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Variable electrode 20 Fixed electrode 16, 18 Insulating film 17 Conductive layer 40 Convex structure 41, 43 Conductive material part 42 Slit

Claims (8)

A pair of counter electrodes, at least one of which is variable;
A convex structure is provided on the facing surface of at least one of the electrodes,
And a part of the variable electrode corresponding to the convex structure part or the opposed part of the convex structure is an electrostatic actuator electrically separated,
The electrical separation is performed by forming a slit in the conductive layer of the variable electrode, and the inner peripheral shape of the slit projected onto the electrode surface is the same as the convex shape projected onto the electrode surface, or the convex shape. An electrostatic actuator comprising: In a pair of counter electrodes, at least one of which is variable,
An electrostatic actuator provided with a convex structure on the opposing surface of at least one electrode,
The convex structure portion and the opposite portion are electrically separated from the respective electrodes, and at least the variable electrode is electrically separated by forming a slit in the conductive layer and projected onto the electrode surface. The electrostatic actuator according to claim 1, wherein an inner peripheral shape of the slit is the same as a convex shape projected on the electrode surface or includes the convex shape.   The convex structure includes a position where the variable electrode is most easily displaced, and when the position where the variable electrode is most easily displaced is a line shape, the edge of the convex structure is substantially orthogonal to at least one of the electrodes. The electrostatic actuator according to claim 1, wherein the electrostatic actuator is formed in an island shape. A nozzle, a liquid chamber communicating with the nozzle, a variable electrode, a fixed electrode provided outside the liquid chamber so as to face the variable electrode, and a convex structure provided on a facing surface of at least one of the electrodes; and A portion of the variable electrode corresponding to the convex structure portion or the opposite portion of the convex structure is electrically disconnected, and the variable electrode is displaced by applying a voltage between the variable electrode and the fixed electrode. A droplet discharge head having a plurality of electrostatic actuators for discharging droplets from the nozzles by mechanical force generated in the variable electrode,
Electrical separation is performed by forming slits in the conductive layer of the variable electrode, and the inner peripheral shape of the slit projected onto the electrode surface is the same as or including the convex shape projected onto the electrode surface. A droplet discharge head characterized by the above. A nozzle, a liquid chamber communicating with the nozzle, a variable electrode, a fixed electrode provided outside the liquid chamber so as to face the variable electrode, and a convex structure provided on a facing surface of at least one of the electrodes; A droplet discharge head having a plurality of electrostatic actuators that displace the variable electrode by applying a voltage between an electrode and the fixed electrode, and discharge droplets from the nozzle by a mechanical force generated in the variable electrode Because
The convex structure portion and the opposing portion are electrically separated from the respective electrodes, and at least the variable electrode is electrically separated by forming a slit in the conductive layer and projected onto the electrode surface. The droplet discharge head is characterized in that an inner peripheral shape of the slit is the same as or includes the convex shape projected on the electrode surface.   The convex structure includes a position where the variable electrode is most easily displaced, and when the position where the variable electrode is most easily displaced is a line, the line and the edge of the convex structure are substantially orthogonal to each other on at least one electrode. The droplet discharge head according to claim 4, wherein the droplet discharge head is formed in an island shape.   A droplet discharge apparatus comprising the droplet discharge head according to claim 4.   An inkjet recording apparatus comprising the droplet discharge head according to claim 4.

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