JP2010143159A - Electrostatic actuator, liquid discharge head, and image forming apparatus - Google Patents

Abstract

An object of the present invention is to seal a sealing material that flows out to an unnecessary part when sealing an open air part that introduces gas into the gap for the purpose of eliminating the differential pressure between the internal pressure of the air gap and atmospheric pressure and improving reliability. Cause connection failure and characteristic failure.
SOLUTION: A communication passage 15 communicating with a gap 13, an atmosphere opening portion 16 having an atmosphere opening hole 42 communicating the communication passage 15 with the outside, and a sealing material for sealing the atmosphere opening hole 42 of the atmosphere opening portion 16. 36 and a convex stepped portion 37 surrounding the atmosphere opening portion 16, and when the atmosphere opening hole 42 is sealed with the sealing material 36 after gas introduction through the atmosphere opening hole 42, the sealing material 36 is provided. Even in the stage where the fluidity remains, the convex stepped portion 37 is dammed up, and the flow out to places other than the atmosphere opening portion 16 is prevented.
[Selection] Figure 9

Description

  The present invention relates to an electrostatic actuator, a liquid discharge head, and an image forming apparatus.

  In general, a printer, a fax machine, a copier, a plotter, or an image forming apparatus that combines a plurality of these functions includes, for example, a recording head composed of a liquid ejection head that ejects ink droplets, It is also referred to as “paper”, but the material is not limited, and a recording medium, recording medium, transfer material, recording paper, etc. are also used synonymously.) Some perform formation (recording, printing, printing, and printing are also used synonymously).

  The “image forming apparatus” means an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. “Formation” not only applies an image having a meaning such as a character or a figure to a medium, but also applies an image having no meaning such as a pattern to the medium (a liquid discharge device that simply discharges droplets). Means). Further, the “ink” is not limited to ink in a narrow sense and is not particularly limited as long as it becomes liquid when ejected. For example, DNA, treatment liquid, sample, resist, pattern material Etc. are also included.

  Liquid discharge heads include those that use piezoelectric actuators such as electromechanical transducers, those that use thermal actuators that use film boiling as electrothermal transducers, and electrostatic forces that use electrostatic force between the diaphragm and electrodes. There are some that use electric actuators. Among them, heads using electrostatic actuators have advantages over other types of heads in terms of miniaturization, high speed, high density, and power saving. have.

  In such a liquid discharge head using an electrostatic actuator, the accuracy of the dimension (gap length) of the gap (gap) between the diaphragm and the electrode greatly affects the characteristics thereof. In the case of the liquid discharge head used in the above, if the variation in the characteristics of the actuators is large, the printing accuracy and the reproducibility of the image quality will be significantly reduced. Therefore, in the configuration in which two substrates are joined as described in Patent Document 1, the gap accuracy is lowered, so that a gap is formed by sacrificial layer etching as described in Patent Documents 1 and 2. Is done.

  In the electrostatic actuator, for the purpose of eliminating the differential pressure between the internal pressure of the air gap and the atmospheric pressure or improving the reliability of the actuator, a communication passage that communicates each air gap is provided to introduce gas into the air gap. ing. For example, as disclosed in Patent Document 2, in order to form a hydrophobic film inside the gap between the diaphragm and the individual electrode for the purpose of improving the durability of the actuator, a communication path communicating with the actuator gap, An air release part that connects the communication path to the outside is provided, and gas and liquid that become a hydrophobic film are introduced from this air release part through the communication path into the actuator gap, and after forming the hydrophobic film on the inner surface of the gap, the atmosphere is released. What sealed the part with the sealing material is known.

JP 2007-77864 A JP 2008-077849 A

  However, for example, in the electrostatic actuator substrate described in Patent Document 2, the actuator gap, the communication path, and the atmosphere opening portion are formed by a single sacrificial layer etching process. When introducing a gas or a liquid to be a hydrophobic film into the actuator gap, it is necessary to open an atmosphere opening hole in a portion corresponding to the diaphragm of the actuator in the atmosphere opening portion.

  On the other hand, after forming the hydrophobic film in the actuator gap, it is necessary to confine the gas that becomes the hydrophobic film in the actuator gap, and in order to prevent the entry of moisture and foreign matter in the atmosphere from the open air opening hole, For example, it is necessary to seal the air opening hole with an epoxy adhesive and seal the inside of the actuator gap.

  However, when sealing the air opening hole, the sealing material does not originally need to be sealed, for example, in a portion where another substrate is joined, a portion serving as an electrode extraction terminal (pad) to the outside, or a diaphragm region There is a problem that it adheres and causes a failure of bonding or electrical connection with another substrate, an operation failure, a bonding failure, a connection failure, a characteristic failure, or the like.

  This invention is made | formed in view of said subject, and it aims at making a sealing material not reach an unnecessary location with sealing of an air release part.

In order to solve the above problems, an electrostatic actuator according to the present invention is:
In an electrostatic actuator comprising a deformable diaphragm and an electrode facing the diaphragm through a gap,
A communication path communicating with the gap;
An atmosphere opening portion having an atmosphere opening hole for communicating the communication path to the outside;
A sealing material for sealing the atmosphere opening hole of the atmosphere opening portion;
And a convex stepped portion surrounding the atmosphere opening portion.

  Here, the convex step part can be configured to be provided more than double.

  Moreover, the said convex level | step-difference part can be set as the structure formed with the 1 or 2 or more structural film which comprises an actuator.

  The liquid discharge head according to the present invention includes the electrostatic actuator according to the present invention.

  An image forming apparatus according to the present invention includes the liquid ejection head according to the present invention.

  According to the electrostatic actuator according to the present invention, the convex stepped portion surrounding the atmosphere opening portion is provided, so that the sealing material for sealing the atmosphere opening hole is prevented from reaching unnecessary portions. In addition, it is possible to prevent an operation failure, a bonding failure, a connection failure, a characteristic failure, and the like caused by the sealing material reaching other unnecessary portions.

  According to the liquid ejection head according to the present invention, since the electrostatic actuator according to the present invention is provided, a highly reliable electrostatic liquid ejection head can be obtained.

  According to the image forming apparatus according to the present invention, since the liquid discharge head according to the present invention is provided, an image forming apparatus including a highly reliable electrostatic liquid discharge head can be obtained.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective explanatory view of a liquid discharge head according to the present invention, FIG. 2 is an exploded perspective explanatory view of the head, FIG. 3 is a cross-sectional explanatory view along the surface S1 of FIG. It is a cross-sectional explanatory drawing of the liquid chamber long side direction along surface S2.

  The liquid discharge head 100 is of a side shooter type that discharges liquid droplets from nozzle holes provided in the substrate surface portion, and includes an actuator substrate 1 as a first substrate, a flow path substrate 2 as a second substrate, and a first substrate. The nozzle substrate 3 which is the substrate 3 is sequentially laminated, and the liquid chamber (discharge) in which the nozzle 4 for discharging the droplet discharge by joining these three substrates 1 to 3 communicates through the nozzle communication path 5 is used. Chamber) 6, a fluid resistance portion 7 for supplying ink to the liquid chamber 6, and a common liquid chamber 8. Each liquid chamber is partitioned by a liquid chamber space 9.

  As shown in FIG. 2, the actuator substrate 1 sacrifices the vibration plate 12 forming a vibration plate region (deformable region) 12 </ b> A that forms a part of the wall surface of the liquid chamber 6, and the vibration region 12 </ b> A of the vibration plate 12. The individual electrodes 14 that face each other through a gap (gap) 13 formed by layer etching are provided, and the diaphragm 12 and the individual electrodes 14 constitute an electrostatic actuator corresponding to each liquid chamber 6.

  The actuator substrate 1 is formed with a common communication path (communication pipe) 15 in the direction in which the nozzles 4 are arranged so that the air gaps 13 communicate with each other and communicate with the outside of the actuator substrate 1 itself. The gap 13 is communicated with the passage 15 via the individual communication passage 15A, and the other end portion of the common communication passage 15 is communicated with an atmosphere opening portion 16 for opening the common communication passage 15 to the atmosphere. The air release portion 16 is sealed with a sealant at the stage where the actuator substrate 1 is formed.

  As shown in FIG. 3, the actuator substrate 1 of FIG. 3 forms an etchable electrode forming layer 24 to be an individual electrode 14 on an insulating film 22 on a silicon substrate 21, and an insulating film 25 on the electrode forming layer 24. Further, a sacrificial layer 27 is formed on the insulating film 25 to form the air gap 13, the common communication path 15, the individual communication path 15 </ b> A, and the air release space of the air release portion 16. As shown in FIG. 4, a sacrificial layer removal hole 29 is formed in the insulating film 28, and the sacrificial layer 27 is removed from the sacrificial layer removal hole 29 to remove the sacrificial layer 27 and the common communication path 15. In addition, the individual communication passage 15 </ b> A and the open air gap of the open air portion 16 are formed, and the diaphragm member 30 is laminated on the insulating film 28.

  The insulating film 25 formed on the surface of the individual electrode 14 is used to prevent an electrical short circuit with the diaphragm 12 and to protect the individual electrode 14 during etching of the sacrificial layer in order to form the gap 13. . In addition, the insulating film 28 on the diaphragm 12 side also prevents an electrical short circuit with the individual electrode 14, and a part of the diaphragm member 30 formed on the insulating film 28 at the time of sacrificial layer etching for forming the gap 13. It is for protecting the layer. The actuator substrate 1 is provided with a supply port 18 for supplying ink from the outside to the common liquid chamber 8 of the flow path substrate 2.

  The flow path substrate 2 bonded onto the actuator substrate 1 communicates with, for example, a silicon substrate having a crystal orientation (110), a liquid chamber (discharge chamber) 5, and each liquid chamber 6 via a fluid resistance portion 7. A common liquid chamber 8 composed of a groove or a recess is provided.

  The nozzle substrate 3 bonded on the flow path substrate 2 uses, for example, nickel having a thickness of 50 μm, and the nozzle 4 can be formed by a known method such as dry or wet etching or laser processing.

  In the liquid ejection head 100 configured as described above, the individual electrodes corresponding to the nozzles 4 that eject ink droplets based on image data from a control unit (not shown) in a state where each liquid chamber 6 is filled with ink. 14, a pulse voltage of 40 V is applied by a drive pulse generation circuit. By applying this voltage, a positive charge is charged on the surface of the individual electrode 14, and a suction action by an electrostatic force acts between the individual electrode 14 and the diaphragm 12 including the diaphragm electrode, so that the diaphragm 12 Bends downward. Thereby, since the volume of the liquid chamber 6 is expanded, the ink for the volume flows from the common liquid chamber 9 into the liquid chamber 6 through the fluid resistance portion 7.

  Thereafter, by setting the pulse voltage applied to the individual electrode 14 to 0 V (stopping the application), the diaphragm 12 bent downward by the electrostatic force returns to the original position due to its own rigidity. As a result, the pressure in the liquid chamber 6 rises rapidly, and ink droplets are ejected from the nozzles 4 communicating with the liquid chamber 6. Then, by repeating this operation and continuously ejecting droplets from the nozzle 4, an image is formed on a recording medium (paper) disposed facing the liquid ejection head 100.

  Here, in the electrostatic actuator, the electrostatic force acting between the individual electrode 14 and the diaphragm 12 is F: electrostatic force acting between the electrodes, ε: dielectric constant, S: area of the opposing surface of the electrode, When d: distance between electrodes and V: applied voltage, the following equation (1) is given.

  In other words, the electrostatic force F is inversely proportional to the square of the distance d between the electrodes and directly proportional to the square of the applied voltage V. Therefore, in order to reduce the driving voltage of the electrostatic actuator or the droplet discharge head 100 equipped with the electrostatic actuator, the distance (gap height: gap length) between the individual electrode 14 and the diaphragm 12 is reduced. It becomes important.

  Therefore, as described above, by forming the gap 13 by sacrificial layer etching, a minute gap interval can be formed accurately and stably without variation, so that there is little variation in operating characteristics between the actuators, and there is little static. An electric actuator can be obtained, and by applying this electrostatic actuator to the liquid discharge head 100, variations in droplet discharge characteristics between the nozzles 4 can be reduced, and a high-quality image can be formed. it can.

  Next, the electrostatic actuator according to the first embodiment of the present invention in this liquid discharge head will be described with reference to FIGS. 5 is an explanatory plan view showing the actuator substrate 1 in a transparent state in the actuator, FIG. 6 is an explanatory sectional view taken along the line X1-X1 in FIG. 5, and FIG. 7 is an explanatory sectional view taken along the line X2-X2 in FIG. FIG. 8, FIG. 8 is an explanatory plan view of the atmosphere opening portion of the actuator substrate 1, FIG. 9 is an explanatory sectional view taken along line X3-X3 in FIG. 8, and FIG. 10 is an explanatory sectional view taken along line Y3-Y3 in FIG. .

  The diaphragm 12 of the actuator substrate 1 is composed of the insulating film 28 and the diaphragm member 30 as described above, and the diaphragm region 12A of the diaphragm member 30 is separated by the separation groove 31 as shown in FIG. Has been. As shown in FIG. 6, the diaphragm member 30 is formed by sequentially laminating a diaphragm electrode (upper electrode) 32, a film stiffness adjusting film (nitride film) 33, a deflection preventing film 34, and a resin film 35 on an insulating film 28. Formed. Further, each diaphragm region 12A on the insulating film 22 formed on the surface of the silicon substrate 21 has a short side length a and a long side length b, for example, a short side length a of 60 μm and a long side length as shown in FIG. b is 1000 μm.

  The gaps 13 between these diaphragm regions 12A and the individual electrodes 14 are formed by sacrificial layer etching. In sacrificial layer etching, a sacrificial layer 27 having the height and thickness of the gap 13 is formed on the insulating film 25, and then an insulating film 28, a diaphragm electrode 32, and a film stiffness adjusting film (nitride film) 33 are sequentially stacked. Then, a sacrificial layer removal hole 29 penetrating them is formed, and the sacrificial layer 27 in the space 13 is removed through the sacrificial layer removal hole 29.

  In the sacrificial layer etching for removing the sacrificial layer 27, the common communication passage 15 and the individual communication passage 15 </ b> A and the air release space 41 of the air release portion 16 are formed together with the formation of the space 13. In this manner, the gap 13 between the diaphragm and the electrode, the common communication path 15 and the individual communication path 15A, and the air release space 41 of the air release portion 16 are simultaneously formed by removing the same sacrificial layer. Alternatively, the passages can be communicated with each other, the configuration is simple, the number of manufacturing steps is small, and the mass productivity and the yield are improved.

  Here, as shown in FIG. 5, the sacrificial layer removal holes 29 are arranged at equal intervals in the long side direction of the diaphragm region 12 </ b> A and at intervals equal to or shorter than the short side length a of the diaphragm region 12 </ b> A. The opposite sides of the plate region 12A are formed to be the same. Since the sacrificial layer etching is isotropic, sacrificial layer removal efficiency is higher when the sacrificial layer removal hole 29 is arranged in the center of the diaphragm region 12A, and the processing time can be shortened. Since the removal hole 29 may affect the vibration characteristics of the actuator, the sacrificial layer removal hole 29 is preferably disposed outside the diaphragm region 12A. Further, by arranging a plurality of sacrificial layer removal holes 29, the sacrificial layer 27 can be efficiently removed, and the gap 13 can be formed efficiently.

  Further, the sacrificial layer removal hole 29 for forming the open air gap 41 of the open air portion 16 is an efficient sacrificial layer in consideration of the area ratio with the diaphragm region 12A as shown in FIGS. Sacrificial layer removal holes 29 are arranged so that 27 is removed.

  After the sacrificial layer etching, the sacrificial layer removal hole 29 is completely sealed with the film deflection preventing film 34. Thereafter, although not shown, a wiring for taking out to the external electrode and a supply port 18 for supplying ink to the common liquid chamber 8 are formed, and a resin film 35 in contact with the droplet is formed. At this time, in the wiring forming process for taking out to the external electrode, the convex stepped portion 37 is formed so as to surround the atmosphere opening hole 42 of the atmosphere opening portion 16 at the same time. 16 to be a recess.

  Further, the atmosphere opening portion 16 is opened with an atmosphere opening hole 42 communicating with the inside atmosphere opening gap 41, and the atmosphere 13 is opened to the atmosphere through the common communication path 15 and the individual communication path 15A of the atmosphere opening hole 42 and the atmosphere opening gap 41. Alternatively, a hydrophobic film forming material such as hexamethyldisilazane (HMDS) is introduced into the gap 13. At this time, in order to form the atmosphere opening hole 42 in the atmosphere opening portion 16 region, the diaphragm 12 in the atmosphere opening portion 16 region is removed physically by a laser method. Alternatively, when the atmosphere opening hole 42 of the atmosphere opening portion 16 is formed by a litho-etching method capable of fine processing, the area of the atmosphere opening portion 16 can be reduced and the generation of foreign matters can be suppressed as compared with the laser method and the physical method. In addition, since the surface state is simple, there is almost no influence on the next step, which is more preferable.

  After introducing the air release or hydrophobic film forming material, the air release hole 42 of the air release portion 16 is completely sealed with an epoxy resin or the like.

  Here, at the time of sealing the air opening hole 42 of the air opening portion 16, the sealing material flows until curing and does not need to be sealed, for example, a portion to which another substrate is joined or an electrode extraction terminal ( If it flows and adheres to a portion to be a pad) or a diaphragm region, it becomes a failure or operation failure of bonding or electrical connection with another substrate, resulting in bonding failure, connection failure, or characteristic failure. Further, when the sealing material 36 flows, the air opening hole 42 may not be sealed in a state in which the sealing property is sufficiently secured, and a problem relating to reliability such as deterioration of durability over time also occurs.

  Therefore, as in the present invention, the projecting step portion 37 surrounds the atmosphere opening portion 16 so that the sealing material 36 stays in the region surrounded by the projecting step portion 37 and the atmosphere opening hole. 42 can be sealed with a sufficient film thickness. As a result, an electrostatic actuator free from malfunction can be obtained, the manufacturing yield of the electrostatic actuator can be improved, and a stable electrostatic actuator can be obtained.

  Next, the manufacturing process of the actuator substrate will be described with reference to FIGS. 11 is a cross-sectional explanatory view of the manufacturing process showing a portion along line X1-X1 in FIG. 5, FIG. 12 is a cross-sectional explanatory view of the manufacturing process following FIG. 11, and FIG. 13 is a cross-sectional view along line X2-X2 of FIG. FIG. 14 is a cross-sectional explanatory view of the manufacturing process following FIG. 13, FIG. 15 is a cross-sectional explanatory view of the manufacturing process showing the portion along the line X3-X3 of FIG. 8, and FIG. 17 is a cross-sectional explanatory view of the manufacturing process, FIG. 17 is a cross-sectional explanatory view of the manufacturing process showing a portion along the line Y3-Y3 of FIG. 8, and FIG. 18 is a cross-sectional explanatory view of the manufacturing process following FIG.

  As shown in FIGS. 11, 13, 15, and 17, (a), for example, a 400 μm-thick silicon (Si) substrate 21 has a surface (here, both surfaces) having a 1.5 μm-thick insulating film (thermal). As an electrode forming layer for forming the individual electrodes 14 on the insulating film 22, an oxide film is formed, and phosphorus-doped polysilicon (symbol 14A in the air opening portion 16) is formed to a thickness of 0.3 μm. To do.

  Then, a separation groove 40 is formed in the polysilicon (electrode formation layer) by lithoetching to separate and pattern the individual electrode 14 and the portion 51 constituting the partition wall, and the supply port 18 penetrating the silicon substrate 21 later is formed. The portion 53 to be formed is removed. Thereafter, a CVD oxide film is deposited to a thickness of 0.1 μm, and an insulating film 25 is formed on the individual electrode 14 made of polysilicon and the portion 51 constituting the partition and in the isolation groove 40. Then, the insulating film 25 is removed by a litho-etching method later on the portion 54 that forms the common communication passage 15, the portion that forms the individual communication passage 15 </ b> A, and the portion 55 that forms the air opening gap 41.

  Next, as shown in FIGS. 11, 13, 15, and 17 (b), as a sacrificial layer 27 on the inter-insulating film 25, non-doped polysilicon is formed to a thickness of 0.2 μm as a gap. The film is formed by the method. Then, polysilicon is separated and patterned into a portion 57 that becomes the gap 13, a portion 58 that constitutes the partition wall, a portion 59 that becomes the individual communication passage 15 </ b> A, and a portion 60 that becomes the common communication passage 15 by lithoetching, thereby forming the separation groove 61. At the same time, the portion corresponding to the portion 53 to be the supply port 18 is removed.

  At this time, as shown in FIGS. 15 and 17B, the portion that becomes the atmosphere opening portion 16 is separated and patterned into a portion 70 that becomes the atmosphere opening gap 41 and a portion 71 that constitutes the partition wall. A groove 61 is formed. Thus, by using polysilicon as the material for forming the sacrificial layer, a general-purpose technique generally known as the sacrificial layer removing step can be used, and there is selectivity with other materials, and the degree of freedom of the process. Therefore, it is possible to obtain a high-cost, low-cost, excellent mass-productivity and stable actuator.

  After the formation, separation, and patterning of the sacrificial layer 27, the air release portion 16 is formed on the portion 57 that becomes the gap 13, the portion 58 that forms the partition wall, the portions 59 and 60 that become the individual communication passage 15 </ b> A, and the common communication passage 15. A CVD oxide film is deposited on the portion 70 to be the air opening gap 41, the portion 59 to be the common communication path, and the portion 71 constituting the partition wall to form the insulating film 28 with a thickness of 0.1 μm. At this time, the insulating film 28 is also formed in the isolation trench 61.

  Next, as shown in FIGS. 11, 13, 15, and 17 (c), a phosphorus-doped polysilicon layer to be a diaphragm electrode layer 32 is formed on the insulating film 28 with a thickness of 0.1 μm. The polysilicon layer is separated into a diaphragm electrode layer 32 and a portion 61 constituting the partition wall by a litho-etching method, and the portion 53 serving as the supply port 18 is removed to form an opening.

  At this time, in order to prevent the diaphragm electrode layer 32 made of the same material as the sacrificial layer 27 from being etched at the time of sacrificial layer etching, an opening 62 having a larger opening diameter than the sacrificial layer removal hole 29 to be formed later is formed. Further, in the portion that becomes the atmosphere opening portion 16, as shown in each of FIGS. 15 and 17, the polysilicon layer that becomes the diaphragm electrode layer 32 is separated and patterned by a litho-etching method, and sacrifice that is formed later. An opening 62 larger than the layer removal hole 29 is formed. Then, a nitride film having a thickness of 0.15 μm is deposited on the diaphragm electrode layer 32 as the stiffness adjusting layer 33 of the diaphragm 12 by the LP-CVD method. The rigidity adjusting film 33 made of the nitride film is also formed in the opening 62 to cover the end face side of the opening 62 of the diaphragm electrode layer 32.

  Thereafter, as shown in FIGS. 11, 13, 15, and 17 (d), a sacrificial layer removal hole 29 having an opening diameter of 2 μm is formed through the nitride film as the film stiffness adjusting layer 33 and the insulating film 28 by a lithoetch method. Then, the film rigidity adjusting layer (nitride film) 33, the insulating film 25, and the insulating film 28 in the portion that becomes the supply port 18 are removed, and the processing hole 63 of the supply port 18 is formed. Then, for example, by performing sacrificial layer etching such as SF6 plasma processing or dry etching with XeF2 gas to completely remove the sacrificial layer 27 of the portion 57 that becomes the gap 13, the gap 13, the individual communication path 15A and the common communication path 15A. A passage 15 is formed. Although the sacrificial layer etching is performed by dry etching, a wet etching method using a TMAH solution or a KOH solution may be used.

  At this time, the sacrificial layer removal hole 29 having an opening diameter of 2 μm is also formed in the atmosphere opening portion 16 through the nitride film and the insulating film 28 as the stiffness adjusting layer 33 by the lithoetch method, as shown in each of FIGS. To do. By the sacrificial layer etching, the portion 55 that becomes the air opening gap 41 and the common communication path 15 are formed.

  Next, as shown in FIGS. 12, 14, 16, and 18 (a), for the purpose of sealing the sacrificial layer removal hole 29, a film deflection preventing film 34 is formed by atmospheric pressure CVD. The film thickness at this time is set to a film thickness capable of sealing the sacrificial layer removal hole 29, for example, a thickness of 0.6 μm. By carrying out this step, the gap 13 and the open air gap 41 are sealed and completely blocked from the outside air.

  Then, in order to take out an electrode outside, an electrode lead-out wiring pattern is formed using an Al material. At this time, as shown in FIG. 16B and FIG. 18B, the convex stepped portion 37 is formed in the wiring layer so as to surround the atmosphere opening portion 16 at the same time in the wiring forming step.

  Next, as shown in FIG. 12 and FIG. 14B, after removing the sealing film (film deflection preventing film) 34 in the portion serving as the supply port 18 by a lithoetch method, anisotropic etching, for example, By using an ICP etcher, the silicon substrate 21 is etched so as to penetrate from the front surface to the back surface, and the supply port 18 is formed. Here, by forming the supply port 18 by anisotropic etching, it is possible to obtain a high effect in terms of processing shape controllability, fine workability, processing accuracy, and higher density.

  Thereafter, as shown in FIG. 12, FIG. 14, FIG. 16 and FIG. 18 (c), a resin film 35 having a thickness of 1 μm is formed on the entire actuator substrate surface as a wetted film by vapor deposition polymerization method with excellent coverage. Film. Thereafter, an electrode wiring take-out pad portion (not shown) and the air release portion 16 shown in each of FIGS. 16 and 18 (c) are opened by a lithoetch method. Here, examples of the material used as the resin film 35 include a PBO film (polybenzoxazole), a polyimide film, and polyparaxylylene. However, the material has corrosion resistance to droplets and can be formed by vapor deposition polymerization. Others are acceptable.

  Next, as shown in FIG. 16 and FIG. 18G, the air opening hole 42 is opened by a lithoetch method. Thus, the air gap 13 communicates with the atmosphere via the individual communication passage 15 </ b> A, the common communication passage 15, the air release air gap 41, and the air release hole 42.

  Therefore, in order to improve the reliability of the electrostatic actuator, for example, hexamethyldisilazane (HMDS), which is a water-repellent material, is passed through the air opening hole 42 through the air opening air gap 41, the common communication passage 15, and the individual communication passage 15A. Into the gap 13.

  Thereafter, the air opening hole 42 is sealed with the cured resin 36. At this time, by the convex stepped portion 37 formed so as to surround the atmosphere opening hole 16, the fluid cured resin 36 does not spread to other than the atmosphere opening portion 16 until it is cured, and the atmosphere opening hole 42 is reliably sealed. Can do.

  From the above steps, the actuator substrate 1 on which the electrostatic actuator according to the present invention is formed is completed. Then, by sequentially stacking the actuator substrate 1, the flow path substrate 2 and the nozzle substrate 3, the liquid discharge head 100 including the electrostatic actuator can be manufactured.

  Next, a second embodiment according to the electrostatic actuator of the present invention will be described with reference to FIGS. 19 is an explanatory plan view of the atmosphere opening portion of the actuator substrate in the same embodiment, FIG. 20 is a sectional explanatory view taken along line X4-X4 in FIG. 19, and FIG. 21 is a sectional explanatory view taken along line Y4-Y4 in FIG. is there.

  The convex step portion 38 of the atmosphere opening portion 16 of the actuator substrate 1 is formed by a laminated structure of a wiring layer and a liquid contact film (resin film) 35, and the convex step portion formed by only the single wiring layer of the embodiment. The height of the convex step portion 38 is higher than 37.

  Accordingly, the spread of the fluid cured resin 36 to other than the atmosphere opening portion 16 can be further reliably suppressed, and the atmosphere opening hole 42 can be further reliably sealed, so that the manufacturing yield is reduced. Can be prevented.

  Next, a third embodiment according to the electrostatic actuator of the present invention will be described with reference to FIGS. 22 is an explanatory plan view of the atmosphere opening portion of the actuator substrate in the same embodiment, FIG. 23 is an explanatory sectional view taken along line X5-X5 in FIG. 22, and FIG. 24 is an explanatory sectional view taken along line Y5-Y5 in FIG. is there.

  The convex step portion 39 of the atmosphere opening portion 16 of the actuator substrate 1 is formed by a laminated structure of a wiring layer and a liquid contact film (resin film) 35, and a groove 40 is formed in the convex step portion 39. That is, the convex step portion 39 has a double structure composed of the convex step portions 39a and 39b. Even when the cured resin 36 overflows from the convex stepped portion 39a inside the convex stepped portion 39 of the atmosphere opening portion 16, the actuator substrate 1 stays in the groove 40 between the outer convex stepped portion 39b and is fluid. The spread of the hardened resin 36 other than the atmosphere opening portion 16 can be more reliably suppressed than the convex stepped portion configuration of each of the embodiments.

  From the above, it is possible to realize an actuator substrate having a pressure generating mechanism having high accuracy, high density, and high reliability, which has good productivity and production efficiency, which has been difficult with the prior art.

Next, a liquid cartridge integrated liquid discharge head as another embodiment of the liquid discharge head according to the present invention will be described with reference to FIG.
The liquid cartridge integrated head 80 is formed by integrating a head portion 82 according to the present invention having nozzles 81 and the like, and an ink tank (liquid tank) 83 for supplying a recording liquid (ink) to the head portion 82. Is. Thereby, a liquid cartridge integrated liquid discharge head provided with a highly reliable electrostatic actuator can be obtained.

  Next, an example of the image forming apparatus according to the present invention equipped with the liquid discharge head according to the present invention will be described with reference to FIGS. FIG. 26 is an explanatory side view for explaining the entire configuration of the image forming apparatus, and FIG. 27 is an explanatory plan view of a main part of the apparatus.

  In this image forming apparatus, a carriage 103 is slidably held in a main scanning direction by a guide rod 101 and a guide rail 102 that are horizontally mounted on left and right side plates (not shown), and a driving pulley 106A is driven by a main scanning motor 104. And the driven pulley 106B are moved and scanned in the direction indicated by the arrow (main scanning direction) via the timing belt 105.

  For example, four independent ink jet recording liquid droplets (ink droplets) of black (K), cyan (C), magenta (M), and yellow (Y) are recorded on the carriage 103. The recording head 107 composed of the liquid ejection heads 107k, 107c, 107m, and 107y is arranged in a direction along the main scanning direction, and is mounted with the droplet ejection direction facing downward. In addition, although the independent liquid discharge head is used here, it is also possible to employ a configuration in which one or a plurality of heads having a plurality of nozzle rows for discharging recording liquid droplets of each color are used. Further, the number of colors and the arrangement order are not limited to this.

  The carriage 103 is equipped with a sub tank 108 for each color for supplying each color ink to the recording head 107. Ink is supplied to the sub tank 108 from a main tank (ink cartridge) (not shown) via an ink supply tube 109.

  On the other hand, as a sheet feeding unit for feeding a recording medium (sheet) 112 loaded on a sheet stacking unit (pressure plate) 111 such as a sheet feeding cassette 110, the sheets 112 are separated and fed from the sheet stacking unit 111 one by one. Opposite to the half-moon roller (feed roller) 113 and the feed roller 113 to be fed, a separation pad 114 made of a material having a large friction coefficient is provided, and this separation pad 114 is urged toward the feed roller 113 side.

  As a transport unit for transporting the paper 112 fed from the paper feed unit below the recording head 107, a transport belt 121 for electrostatically attracting and transporting the paper 112, and a paper feed unit A counter roller 122 for transporting the paper 112 fed through the guide 115 while sandwiching it between the transport belt 121 and the paper 112 fed substantially vertically upward is changed by about 90 ° and copied on the transport belt 121. A conveying guide 123 for adjusting the pressure and a tip pressure roller 125 urged toward the conveying belt 121 by a pressing member 124. In addition, a charging roller 126 that is a charging unit for charging the surface of the conveyance belt 121 is provided.

  Here, the conveyance belt 121 is an endless belt, is stretched between the conveyance roller 127 and the tension roller 128, and the conveyance roller 127 is rotated from the sub-scanning motor 131 via the timing belt 132 and the timing roller 133. By doing so, it is configured to go around in the belt conveyance direction (sub-scanning direction). A guide member 129 is disposed on the back side of the conveyance belt 121 in correspondence with the image forming area formed by the recording head 107.

  In addition, a slit disk 134 is attached to the shaft of the transport roller 127, and a sensor 135 for detecting the slit of the slit disk 134 is provided, and the encoder 136 is configured by the slit disk 134 and the sensor 135. .

  The charging roller 126 is arranged so as to contact the surface layer of the conveyor belt 121 and rotate following the rotation of the conveyor belt 121, and applies 2.5N to both ends of the shaft as a pressing force.

  Further, an encoder scale 142 having slits is provided on the front side of the carriage 103, and an encoder sensor 143 including a transmission type photosensor for detecting the slits of the encoder scale 142 is provided on the front side of the carriage 103. An encoder 144 for detecting the position of the carriage 103 in the main scanning direction is configured.

  Further, as a paper discharge unit for discharging the paper 112 recorded by the recording head 107, a separation unit for separating the paper 112 from the conveying belt 121, a paper discharge roller 152 and a paper discharge roller 153, and paper discharge A paper discharge tray 154 for stocking the paper 112 to be printed.

  A double-sided paper feeding unit 155 is detachably mounted on the back. The double-sided paper feeding unit 155 takes in the paper 112 returned by the reverse rotation of the transport belt 121, reverses it, and feeds it again between the counter roller 122 and the transport belt 121.

  Further, a maintenance / recovery mechanism 156 for maintaining and recovering the state of the nozzles of the recording head 107 is disposed in a non-printing area on one side of the carriage 103 in the scanning direction. The maintenance / recovery mechanism 156 includes a cap 157 for capping each nozzle surface of the recording head 107, a wiper blade 158 which is a blade member for wiping the nozzle surface, and a discharge unit for discharging the thickened recording liquid. An empty discharge receiver 159 for receiving droplets when performing empty discharge for discharging droplets that do not contribute to recording is provided.

  In the image forming apparatus configured as described above, the sheets 112 are separated and fed one by one from the sheet feeding unit, and the sheet 112 fed substantially vertically upward is guided by the guide 115, and includes the conveyance belt 121 and the counter roller 122. The leading end is guided by the conveying guide 123 and pressed against the conveying belt 121 by the leading end pressure roller 125, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately repeated from the AC bias supply unit (high-voltage power supply) to the charging roller 126 by a control circuit (not shown), that is, alternating voltages are applied, and the conveyor belt 121 alternates. In the charging voltage pattern, that is, in the sub-scanning direction that is the circumferential direction, plus and minus are alternately charged in a band shape with a predetermined width. When the paper 112 is fed onto the conveyance belt 121 charged alternately with plus and minus, the paper 112 is attracted to the conveyance belt 121 by electrostatic force, and the paper 112 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 121. Is done.

  Therefore, by driving the recording head 107 according to the image signal while moving the carriage 103 in the forward and backward directions, ink droplets are ejected onto the stopped paper 112 to record one line, and the paper 112 is After transporting a predetermined amount, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 112 has reached the recording area, the recording operation is finished, and the paper 112 is discharged onto the paper discharge tray 154.

  In the case of double-sided printing, when recording on the front surface (surface to be printed first) is completed, the recording belt 112 is fed into the double-sided paper feeding unit 155 by rotating the conveyor belt 121 in the reverse direction. The paper 112 is reversed (with the back surface being the printing surface), and is fed again between the counter roller 122 and the conveyor belt 121. The timing is controlled, and the sheet is conveyed onto the conveyor bell 121 as described above. After recording on the back side, the sheet is discharged to the discharge tray 154.

  Further, during printing (recording) standby, the carriage 103 is moved to the maintenance / recovery mechanism 155 side, and the nozzle surface of the recording head 107 is capped by the cap 157 so that the nozzles are kept in a wet state. To prevent. In addition, the recording liquid is sucked from the nozzle in a state where the recording head 107 is capped by the cap 157 (referred to as “nozzle suction” or “head suction”), and a recovery operation is performed to discharge the thickened recording liquid or bubbles. Wiping is performed by the wiper blade 158 in order to clean and remove ink adhering to the nozzle surface of the recording head 107 by this recovery operation. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. Thereby, the stable ejection performance of the recording head 107 is maintained.

  Thus, according to this image forming apparatus, it is possible to obtain an image forming apparatus including a highly reliable liquid ejection head.

Next, a micro pump as a micro device provided with the electrostatic actuator according to the present invention will be described with reference to FIG. In addition, the figure is principal part cross-sectional explanatory drawing of the micropump.
This micro pump has an actuator substrate 201 constituted by an electrostatic actuator according to the present invention and a flow path substrate 202, and a flow path 203 through which a fluid flows is formed in the flow path substrate 202. The actuator substrate 201 opposes the diaphragm member 212 that forms the wall surface of the flow path 203 and the deformable region (the diaphragm) 211 of the diaphragm member 212 via a gap (gap) 213 formed by sacrificial layer etching. And an individual electrode 214.

  The configuration of the actuator substrate 201 is the same as that of the embodiment of the liquid discharge head. The insulating film 222 is formed on the silicon substrate 221, the individual electrode 214 is formed on the insulating film 222, and is covered with the insulating film 225. Then, a sacrificial layer 227 is formed on the insulating film 225, and after forming a part of the diaphragm 212, sacrificial layer etching is performed to form a gap 213. Although not shown, the gap 213 is individually connected. A common communication path communicating through the passage is formed.

  The operation principle of the micropump will be described. As in the case of the liquid discharge head described above, by selectively applying a pulse potential to the individual electrode 214, a suction action by an electrostatic force is generated between the diaphragm 211 and the diaphragm 211. Therefore, the diaphragm 211 is deformed to the electrode 214 side. Here, by sequentially driving the diaphragm 211 from the right side in the figure, the fluid in the flow path 203 flows in the direction of the arrow, and the fluid can be transported.

  Thus, by providing the electrostatic actuator according to the present invention, it is possible to obtain a small-sized and low-power-consumption micropump including a highly reliable electrostatic actuator and capable of stable liquid transportation. In order to increase transport efficiency, one or more valves, such as a check valve, may be provided between the deformable regions.

Next, an example of an optical device provided with the electrostatic actuator according to the present invention will be described with reference to FIG. This figure is a schematic configuration diagram of the device.
This optical device has an actuator substrate 301 including a mirror 300 corresponding to a diaphragm whose surface can reflect light and can be deformed. A dielectric multilayer film or a metal film is preferably formed on the surface of the mirror 300 in order to increase the reflectance (these are formed on the resin film surface).

  The actuator substrate 301 includes a deformable mirror 300 and an electrode 314 facing a deformable region (vibrating plate) 311 of the mirror 300 via a predetermined gap 313 on a base substrate 321 on which an insulating film 322 is formed. I have. Further, an insulating film 325 is formed over the electrode 314, and the gap 313 is formed by etching the sacrificial layer 327. Other configurations are different from the electrostatic actuator described in the above-described embodiment of the liquid discharge head in that the diaphragm has a mirror surface, and detailed illustration and description are omitted. To do.

  The principle of this optical device will be described. As in the case of the electrostatic actuator described above, by selectively applying a pulse potential to the electrode 314, between the deformable region 311 of the mirror 300 facing the electrode 314. Since a suction action due to electrostatic force occurs, the deformable region 311 of the mirror 300 is deformed into a concave shape to form a concave mirror. Therefore, when the light from the light source 330 is applied to the mirror 300 via the lens 331, the light is reflected at the same angle as the incident angle when the mirror 300 is not driven, but is driven when the mirror 300 is driven. Since the deformable region 311 becomes a concave mirror, the reflected light becomes divergent light. Thereby, an optical modulation device can be realized.

  Thus, by providing the electrostatic actuator according to the present invention, a small and low power consumption optical device can be obtained.

  An example in which this optical device is applied will be described with reference to FIG. In this example, the above-described optical devices are two-dimensionally arranged, and the deformable region 311 of each mirror 300 is driven independently. Although a 4 × 4 array is shown here, it is possible to arrange more than this.

  Accordingly, similarly to FIG. 29 described above, the light from the light source 330 is irradiated to the mirror 300 via the lens 331, and the light incident on the portion where the mirror 300 is not driven enters the projection lens 332. On the other hand, a portion where the deformable region 311 of the mirror 300 is deformed by applying a voltage to the electrode 314 becomes a concave mirror, so that light diverges and hardly enters the projection lens 332. The light incident on the projection lens 332 is projected on a screen (not shown) or the like, and an image can be displayed on the screen.

  In the above embodiment, as the liquid ejection head, in addition to ink, other liquids such as a liquid ejection head that ejects a liquid resist as droplets, a liquid ejection head that ejects DNA samples as droplets, and the like. It can also be applied to a discharge head. The electrostatic actuator can also be applied to micro pumps, optical devices (light modulation devices), micro switches (micro relays), multi-optical lens actuators (light switches), micro flow meters, pressure sensors, and the like. .

FIG. 4 is a perspective explanatory view of a liquid discharge head according to the present invention. It is a disassembled perspective explanatory drawing of the head. FIG. 2 is a cross-sectional explanatory view taken along a surface S1 in FIG. FIG. 2 is an explanatory cross-sectional view along a surface S2 of FIG. It is a plane explanatory view showing an actuator substrate in a permeation state in an electrostatic actuator concerning a 1st embodiment of the present invention. FIG. 6 is a cross-sectional explanatory view taken along line X1-X1 in FIG. 5. FIG. 6 is a cross-sectional explanatory view taken along line X2-X2 of FIG. It is a plane explanatory view of the atmosphere release part of the actuator substrate. FIG. 9 is a cross-sectional explanatory view taken along line X3-X3 in FIG. FIG. 9 is a cross-sectional explanatory view taken along line Y3-Y3 of FIG. It is sectional explanatory drawing of the manufacturing process which shows the part which follows the X1-X1 line | wire of FIG. 5 with which it uses for description of the manufacturing process of the same actuator substrate. FIG. 12 is a cross-sectional explanatory diagram of the manufacturing process following FIG. 11. FIG. 6 is a cross-sectional explanatory view of the manufacturing process showing a portion along line X2-X2 in FIG. 5. FIG. 14 is an explanatory cross-sectional view of the manufacturing process following FIG. 13. FIG. 9 is a cross-sectional explanatory view of the manufacturing process showing a portion along line X3-X3 in FIG. 8. FIG. 16 is a cross-sectional explanatory diagram of the manufacturing process following FIG. 15. FIG. 9 is a cross-sectional explanatory view of the manufacturing process showing a portion along line Y3-Y3 in FIG. 8. FIG. 18 is a cross-sectional explanatory diagram of the manufacturing process following FIG. 17. It is plane explanatory drawing of the air release part of the actuator board | substrate in 2nd Embodiment which concerns on the electrostatic actuator of this invention. FIG. 20 is an explanatory cross-sectional view taken along line X4-X4 of FIG. FIG. 20 is an explanatory cross-sectional view taken along line Y4-Y4 of FIG. It is plane explanatory drawing of the air release part of the actuator board | substrate in 3rd Embodiment which concerns on the electrostatic actuator of this invention. It is sectional explanatory drawing which follows the X5-X5 line | wire of FIG. It is sectional explanatory drawing which follows the Y5-Y5 line | wire of FIG. FIG. 6 is a perspective explanatory view for explaining another example of the liquid ejection head according to the present invention. 1 is a side explanatory view illustrating an example of an image forming apparatus according to the present invention. FIG. 2 is an explanatory plan view of a main part of the image forming apparatus. It is typical explanatory drawing explaining an example of the micropump which concerns on this invention. It is explanatory drawing explaining an example of the optical device which concerns on this invention. It is an isometric view explanatory drawing used for description of the application example of the same optical device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Actuator board | substrate 2 ... Flow path board | substrate 3 ... Nozzle board | substrate 4 ... Nozzle 5 ... Nozzle communication path 6 ... Liquid chamber (discharge chamber)
DESCRIPTION OF SYMBOLS 7 ... Fluid resistance part 9 ... Liquid chamber space | interval wall 10 ... Common liquid chamber 11 ... Diaphragm 12 ... Diaphragm member 13 ... Gap 14 ... Individual electrode 15 ... Common communication path 15A ... Individual communication path 16 ... Atmospheric release part 21 ... Silicon Substrate 22 ... Insulating layer (film)
24 ... Electrode forming layer 25 ... Insulating film (intermediate film)
26 ... Opening 27 ... Sacrificial layer 28 ... Insulating film 29 ... Sacrificial layer removal hole 32 ... Diaphragm electrode (upper electrode)
33 ... Film bending prevention film (nitride film)
34 ... Membrane stiffness adjustment film 35 ... Resin film (wetted film)
36 ... Resin film (sealing film)
37, 38, 39 ... convex stepped portion 40 ... groove 42 ... air opening hole 80 ... liquid cartridge 107k, 107c, 107m, 107y ... recording head (liquid ejection head)
201, 301 ... Actuator board

Claims (5)

In an electrostatic actuator comprising a deformable diaphragm and an electrode facing the diaphragm through a gap,
A communication path communicating with the gap;
An atmosphere opening portion having an atmosphere opening hole for communicating the communication path to the outside;
A sealing material for sealing the atmosphere opening hole of the atmosphere opening portion;
An electrostatic actuator, comprising: a convex step portion surrounding the atmosphere opening portion.   The electrostatic actuator according to claim 1, wherein the convex stepped portion is provided more than double.   3. The electrostatic actuator according to claim 1, wherein the convex stepped portion is formed of one or more constituent films constituting the actuator.   4. A liquid discharge head comprising an electrostatic actuator for discharging droplets from a nozzle, wherein the electrostatic actuator is the electrostatic actuator according to claim 1. Discharge head.   An image forming apparatus equipped with a liquid discharge head for discharging liquid droplets, wherein the liquid discharge head is the liquid discharge head according to claim 4.

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