JP2008030337A - Liquid ejecting head, liquid ejector and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the rigidity adjustment of a vibrating plate cannot be performed on the whole or locally without being accompanied by the reduction of a vibrating-plate area rate and a substantial increase of process. <P>SOLUTION: A vibrating plate area 12A of the vibrating plate 12 and a fixed electrode 14A are faced through an aperture 13. In the side of the vibrating plate 12, projections 41 which serve as two or more beams located along the short arm direction of the vibrating plate are arranged at a required spacing and in a required area in the long arm direction of the vibrating plate. In the side of the fixed electrode 14A, a grooved part 42 into which the projection 41 serving as the beam at the side of the vibrating plate 12 is formed as deep as penetrating the fixed electrode 14A. The rigidity of the vibrating plate 12 is adjusted in the area wherein the projection 41 serving as the beam at the side of the vibrating plate 12 is arranged and formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid discharge head, a liquid discharge apparatus, and an image forming apparatus, and more particularly, to an electrostatic liquid discharge head, a liquid discharge apparatus including the same, 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 liquid droplets of recording liquid (liquid). Using a liquid ejection apparatus, while conveying a medium (hereinafter also referred to as “paper”, the material is not limited, and a recording medium, a recording medium, a transfer material, recording paper, and the like are also used synonymously). In some cases, a recording liquid (hereinafter also referred to as ink) as a liquid is attached to a sheet to form an image (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” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium. The “liquid” is not limited to recording liquid and ink, and is not particularly limited as long as it becomes a fluid when ejected, and includes, for example, a DNA sample, a resist, a pattern material, and the like. It is. Further, the “liquid ejecting apparatus” is an apparatus that ejects liquid from a liquid ejecting head and is not limited to an apparatus that forms an image.

  The liquid discharge head includes a nozzle that discharges droplets, a liquid chamber (also referred to as a discharge chamber, a pressure chamber, a pressure chamber, an ink flow path, and the like) that communicates with the nozzle, and a wall surface of the liquid chamber. It has a variable electrode that constitutes at least a part of the diaphragm to be formed, and a counter electrode that faces this variable electrode, and the voltage is applied between the electrodes to displace the variable electrode (diaphragm) with an electrostatic force. An electrostatic liquid discharge head including an electrostatic actuator that generates pressure in a liquid chamber by a mechanical restoring force of a diaphragm is known.

  Such an electrostatic liquid discharge head is an important element for ejecting droplets with a stable displacement characteristic of the diaphragm, and diaphragm rigidity is one of the important parameters as the displacement characteristic of the diaphragm. It is. Therefore, by devising the configuration (shape) of the diaphragm, the variation in the thickness of the diaphragm is reduced without changing the accuracy of the construction method, and the rigidity of the diaphragm is set finely for each location (area). By doing so, it is attempted to improve the characteristics.

For example, Patent Document 1 discloses that when the diaphragm is thin, the rigidity is insufficient and sufficient ejection force sufficient for ink ejection cannot be obtained. On the other hand, it is difficult to increase the thickness of the diaphragm, and the thickness varies. Since the printing quality and reliability are not good, a support column that supports the part other than the outer periphery of the diaphragm and restricts the deformation of the diaphragm is provided on the electrode (fixed electrode) substrate or the flow path substrate. Is described.
JP 07-246706 A

In Patent Document 2, a high drive compliance portion composed of a low-rigidity portion having lower rigidity than other portions is formed on a part of the diaphragm, for example, a portion thinner than other portions and a portion having a wider width than other portions. Thus, it is described that the high drive compliance portion is a driven vibration means, and the opposing wall facing the high drive compliance section is a vibration regulating means.
JP 09-314837 A

In Patent Document 3, there is no need to form a minute gap between the diaphragm and the electrode, and a large deformation of the diaphragm can be induced even by applying a relatively low voltage. A configuration is described in which the thickness is increased toward the discharge port.
Japanese Patent Laid-Open No. 10-211697

In Patent Document 4, even if the gap between the diaphragm and the fixed electrode is narrowed in order to reduce the drive voltage, the diaphragm can be displaced sufficiently for ink ejection, and the diaphragm can be driven without contacting the fixed electrode. In order to improve the driving frequency, the diaphragm is made thin near the both ends of the short side and thick at the center, and provided with a step at both ends of the short side under the diaphragm in the gap, and the fixed electrode and the side surface of the step are recessed. A structure is described in which the distance between the thick part of the diaphragm and the individual fixed electrode is longer than the distance between the thick part of the diaphragm and the upper surface of the step.
JP 2000-052551 A

Patent Document 5 describes a configuration in which a displacement control pattern including a concave portion or a convex portion is provided on the diaphragm when the electrodes and the diaphragm are arranged in a non-parallel state.
JP 2001-010036 A

In Patent Document 6, a convex structure is provided on at least one of the opposing surfaces of the pair of opposing electrodes, and the electrode corresponding to the opposing portion of the convex structure is the same as or convex to the convex shape in which the inner peripheral shape is projected. A configuration for forming a slit including a shape is described.
Japanese Patent Laying-Open No. 2005-094948

Patent Document 7 describes that a gap is formed by sacrificial layer etching.
JP 2004-106089 A

In Patent Document 8, when the minimum voltage of the drive voltage that can eject droplets is Vmin and the minimum contact voltage that contacts the surface facing the diaphragm is Vth, Vth ≦ Vmin ≦ 1.25 × Vth, It is described that the rigidity of the diaphragm is defined so as to satisfy the above relationship.
JP 2005-001258 A

Patent Document 9 describes that a convex portion is formed to prevent adsorption between the diaphragm and the electrode.
JP 2004-284098 A

In addition, the diaphragm of the piezo-type liquid discharge head is described in Patent Document 10.
JP 2003-276192 A

  In the above-mentioned patent documents, as a configuration for changing the rigidity of the diaphragm, (1) a configuration in which the width (short side length) of the diaphragm is changed, and (2) a thickness of the diaphragm is changed (concave and convex portions are formed). (3) and (3) a configuration in which a support column for partially restricting the deformation of the diaphragm is provided.

  Here, in the configuration (1), it is only necessary to change the layout (shape) of the diaphragm, so that there is an advantage that the rigidity of the diaphragm can be adjusted without increasing the number of processes. However, in the portion where the width (short side length) of the diaphragm is narrowed, the diaphragm area becomes smaller with respect to the maximum diaphragm width determined by the nozzle pitch (nozzle interval) and processing accuracy (the diaphragm area ratio is reduced), Change the rigidity of the diaphragm within the width (short side direction) of the diaphragm (for example, soften near the both ends of the short side of the diaphragm and stiffen at the center), and adjust the rigidity of the diaphragm locally. There is a problem that it cannot be given.

  With the configuration (2), it is possible to adjust the diaphragm rigidity while maintaining the diaphragm width at the maximum width determined by the nozzle pitch and machining accuracy, and the diaphragm area ratio is higher than that of the configuration (1). The rigidity of the diaphragm can be adjusted locally, such as changing the rigidity of the diaphragm within the width (short side direction). Depending on the arrangement of the concave and convex parts, the rigidity can be given directionality. There is an advantage of being. However, there is a problem that the number of steps increases in order to form portions having different diaphragm thicknesses.

  In the configuration of (3), when the support is formed on the fixed electrode side, there is an advantage that the rigidity of the diaphragm can be adjusted without increasing the number of steps. However, when adjusting the rigidity of a certain region by the support column, other regions are affected accordingly, and there is a region that does not work effectively as a diaphragm. Therefore, unlike (1), the diaphragm area itself does not decrease, The effective diaphragm area ratio is reduced, and for the same reason, it is difficult to adjust the local stiffness without lowering the diaphragm area ratio. In this case, there is a problem that the number of processes increases.

  The present invention has been made in view of the above-mentioned problems, and it is possible to adjust the rigidity of the diaphragm globally and locally without reducing the area ratio of the diaphragm without significantly increasing the number of processes. An object of the present invention is to provide a liquid discharge head capable of giving directionality to the vibration plate rigidity, a liquid discharge apparatus including the liquid discharge head, and an image forming apparatus.

  In order to solve the above-described problems, a liquid discharge head according to the present invention includes a diaphragm that forms a wall surface of a flow path through which a nozzle that discharges droplets communicates, and a gap formed by sacrificial layer etching on the diaphragm. In a liquid discharge head that includes an opposing electrode and deforms the diaphragm with an electrostatic force and ejects liquid droplets by a mechanical restoring force, a convex portion serving as a beam of the diaphragm is formed on the surface of the diaphragm with respect to the electrode. The groove is formed on the electrode side to escape the convex portion of the diaphragm.

  Here, the groove formed on the electrode side penetrates the layer forming the electrode and does not enter the underlying layer on which the electrodes are stacked, and the groove formed on the electrode side is the layer forming the electrode , A structure in which the electrode is further laminated into the underlying layer on which the electrode is laminated, a layer in which the electrode is formed remains over almost the entire area of the underlying layer on which the electrode is laminated, a liquid discharge head It is possible to adopt a configuration in which a liquid storage portion for supplying a liquid is integrated.

  The liquid ejection apparatus according to the present invention and the image forming apparatus according to the present invention include the liquid ejection head according to the present invention.

  According to the liquid discharge head according to the present invention, a convex portion that becomes a beam of the diaphragm is formed on the surface of the diaphragm with respect to the electrode, and a groove that escapes the convex portion of the diaphragm is formed on the electrode side. As a result, the rigidity of the diaphragm can be adjusted globally and locally without reducing the area ratio of the diaphragm without significantly increasing the number of processes, and providing directionality to the diaphragm rigidity. Will also be possible.

  According to the liquid ejection device according to the present invention, since the liquid ejection head according to the present invention is provided, stable droplet ejection characteristics can be obtained. The image forming apparatus according to the present invention includes the liquid ejection head according to the present invention, so that stable droplet ejection characteristics can be obtained and a high-quality image can be formed.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. A liquid discharge head according to a first embodiment of the present invention will be described with reference to FIGS. 1 is an exploded perspective view of the liquid discharge head, FIG. 2 is an explanatory plan view of the head, FIG. 3 is an explanatory view of a diaphragm of the head, and FIG. 4 is a cross section taken along line X1-X1 in FIG. FIG. 5 is a sectional explanatory view taken along line X2-X2 of FIG. 2, FIG. 6 is a partially enlarged sectional explanatory view of FIG. 4, FIG. 7 is a sectional explanatory view taken along line Y1-Y1 of FIG. FIG. 3 is a cross-sectional explanatory view taken along line Y2-Y2 of FIG. Note that the X1-X1, X2-X2, Y1-Y1, and Y2-Y2 lines as the cross-sectional lines are placed in the corresponding locations in the drawings.

  The liquid discharge head is configured by sequentially stacking an actuator substrate 1 as a first substrate, a flow path substrate 2 as a second substrate, and a nozzle plate 3 as a third substrate. 2 and 2 are joined to supply liquid (ink) to the liquid chamber (discharge chamber) 6 and the liquid chamber 6 in which the nozzle 4 that discharges droplets communicates via a nozzle communication path (communication pipe) 5. The fluid resistance portion 7 and the common liquid chamber 8 are formed. Each liquid chamber 8 is partitioned by a liquid chamber interval wall 9. The common liquid chamber 8 is supplied with a liquid from a liquid supply port 19 of the actuator substrate 1.

  The actuator substrate 1 includes a diaphragm 12 that forms a diaphragm region (deformable region) 12A that forms a part of the wall surface of the liquid chamber 6, and a gap formed by sacrificial layer etching in the diaphragm region 12A of the diaphragm 12. An electrostatic actuator corresponding to each liquid chamber 6 is configured by the fixed electrode 14A facing through the (gap) 13 and the diaphragm region 12A and the fixed electrode 14A facing through the gap 13.

  In this actuator substrate 1, an insulating film 22 as a base layer is laminated on a silicon substrate 21, and a fixed electrode 14A, a fixed electrode lead-out portion 14B, and a dummy electrode (spacer) portion 14C serve as electrode forming layers on the insulating film 22. It is formed by etching. A fixed electrode side insulating layer 25 is formed on the surfaces of the fixed electrode 14A, the fixed electrode lead portion 14B, and the spacer portion 14C. On this insulating layer 25, a gap 13 and a spacer portion (residual sacrificial layer) 26 are formed by sacrificial layer etching.

  The diaphragm 12 facing the fixed electrode 14A with the gap 13 interposed therebetween is a diaphragm electrode 28A formed by etching the diaphragm side insulating film 27 and the diaphragm electrode layer laminated on the insulating film 27. And a dummy diaphragm electrode (spacer part) 28B, and a stress adjustment layer 29 (not shown except for FIG. 6, for example, three tetranitride) sequentially laminated on the diaphragm electrode 28A and the dummy diaphragm electrode (spacer part) 28B. Silicon film), diaphragm crack prevention film 30 (for example, silicon dioxide film), and liquid contact film (corrosion resistant film) 31.

  The fixed electrode 14 </ b> A of the actuator substrate 1 is connected to the external electrical connection portion 34 through the wiring 33 from the fixed electrode lead-out portion 14 </ b> B.

  The flow path substrate 2 joined to the actuator substrate 1 via the adhesive layer 35 is, for example, a silicon substrate having a crystal plane orientation (110), a liquid chamber (discharge chamber) 6, and a fluid in each liquid chamber 6. A common liquid chamber 8 communicating with the resistor 7 is provided (actually a groove or a recess).

  The nozzle plate 3 joined to the flow path substrate 2 via the adhesive layer 36 is made of nickel having a thickness of 50 μm, for example, and the nozzle 4 can be formed by a known method such as dry or wet etching or laser processing. it can.

  In the droplet discharge head configured as described above, the nozzles that are desired to discharge the recording liquid based on the image data from the control unit (not shown) in a state where each liquid chamber 6 is filled with the recording liquid (ink). A pulse voltage of 40 V is applied to the fixed electrode 14A corresponding to 4 by the oscillation circuit. By applying this voltage, a positive charge is charged on the surface of the fixed electrode 14, and an electrostatic action acts between the individual electrode 14 and the diaphragm region 12 </ b> A including the diaphragm electrode 28 </ b> A. 12A bends downward. As a result, the volume of the liquid chamber 6 is expanded, and the recording liquid corresponding to that volume flows from the common liquid chamber 8 into the liquid chamber 6 through the fluid resistance portion 7.

  Thereafter, by setting the pulse voltage to the fixed electrode 14A to 0V (stopping the application), the diaphragm region 12A bent downward by the electrostatic force returns to the original position by the restoring force due to its own rigidity. As a result, the pressure in the liquid chamber 6 rises rapidly, and a recording liquid droplet is ejected from the nozzle 4 communicating with the liquid chamber 6. By repeating this operation and continuously ejecting the recording liquid from the nozzles 4, an image is formed on a sheet fed facing the liquid ejection head.

Therefore, a characteristic part according to the present invention in the actuator substrate 1 will be described.
On the surface on the fixed electrode 14 </ b> A side on the diaphragm 12 side, convex portions (protrusions) 41 serving as a plurality of beams having a required length in the short direction of the liquid chamber 6 are provided along the longitudinal direction of the liquid chamber 6. It is formed side by side. Here, as shown in FIG. 3, the plurality of convex portions 41 are arranged up to approximately ½ of the length in the longitudinal direction at substantially the same interval from the nozzle 4 side of the vibration region 12 </ b> A of the diaphragm 12. It is not formed on the 7 side.

  On the other hand, a groove 42 into which the convex portion 41 on the diaphragm 12 side enters is formed on the fixed electrode 14A side. The groove 42 is formed to a depth that penetrates the fixed electrode forming layer forming the fixed electrode 14A (the insulating layer 25 remains in the sense that there is no fixed electrode forming layer).

  Here, the groove 42 on the fixed electrode 14A side can be formed by using a fixed electrode patterning photomask in which the groove 42 is formed when the fixed electrode forming layer is etched to separate the fixed electrode 14A and the like. Therefore, the groove 42 can be formed without changing the construction method or process for forming the conventional fixed electrode 14A or the like by etching.

  In this case, the groove 42 is formed so as to penetrate the fixed electrode forming layer and reach the insulating film 22 as the base layer, like the separation groove for separating the other fixed electrode 14A. The groove 42 is formed only in the portion of the fixed electrode forming layer by forming the fixed electrode forming layer by etching selective to the insulating film 22 as the base layer. It is hardly formed (the selection ratio is not infinite, so a slight depression is formed). As a result, the depth of the groove 42 is substantially the same as the thickness of the fixed electrode forming layer (fixed electrode 14A). As a result, the height of the convex portion 41 on the diaphragm 12 side is also equal to that, The height can be accurately formed.

  In this way, the rigidity of the diaphragm can be adjusted by forming a convex portion as a beam on the surface on the fixed electrode side on the diaphragm side, so the width of the diaphragm is the maximum width determined by the nozzle pitch and processing accuracy The diaphragm area ratio does not decrease. Further, by forming the convex portion, for example, it is possible to make fine adjustments such as locally changing the rigidity of the diaphragm within the width (short side direction) of the diaphragm, or giving directionality to the rigidity of the diaphragm. .

  Also, by forming a groove into which the convex part enters the fixed electrode side, the convex part on the diaphragm side is formed using this groove, and the groove of the fixed electrode is formed by a mask for forming the fixed electrode pattern. Since it can be performed, the convex portion can be formed on the diaphragm side without increasing the number of manufacturing steps by the conventional sacrificial layer etching process.

  In this case, the groove on the fixed electrode side (the groove corresponding to the convex part on the diaphragm side) is formed so as to penetrate the layer forming the fixed electrode and reach the base layer on which the fixed electrode is laminated, It can be formed without causing any increase in the number of steps (it can be formed in the same step as the previous step for forming the fixed electrode) and the etching can be stopped at the base layer, so that the depth of the groove Can be formed with high accuracy, that is, the height of the convex portion on the diaphragm side can be formed with high accuracy.

Next, a second embodiment of the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 9 is an explanatory plan view of the electrode side surface of the diaphragm of the head.
Here, the convex portions 41 serving as a plurality of beams are arranged not densely on the nozzle 4 side of the diaphragm region 12 </ b> A of the diaphragm 12, sparsely on the center portion, and on the fluid resistance portion 7 side. In this case, as shown in FIG. 10, the rigidity on the nozzle side of the diaphragm region 12A is relatively high, and has a three-stage rigidity distribution that is intermediate in the center and low on the fluid resistance part 7 side. Moreover, the convex part 41 used as the some beam is formed in the length W1 substantially the same as the width | variety of a diaphragm short side direction. Depending on the arrangement (density) of the convex portions 41 to be the beams, it is possible to make further changes in multiple stages.

Next, a third embodiment of the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 10 is an explanatory plan view of the electrode side surface of the diaphragm of the head.
Here, the convex portions 41 serving as a plurality of beams have a length W2 in the diaphragm short-side direction shorter than a width in the diaphragm short-side direction, and in the diaphragm short-side direction near the diaphragm center, in the diaphragm longitudinal direction Are arranged at a required interval (including a case where the distance is constant and a case where the distance is not constant). Accordingly, the rigidity in the vicinity of the diaphragm center in the short side direction is relatively high and can be lowered at both ends in the short side direction.

  As a result, the bending shape of the diaphragm when the rigidity in the short side direction of the diaphragm is uniform is large near the center (center) and small at both ends as shown in FIG. Like the form, the vicinity of the diaphragm in the short side direction is relatively high in rigidity, and the bending shape when it is low at both ends in the short side direction is as shown in FIG. 12, with the same amount of displacement (peak position). A larger volume change can be obtained.

  The gap shape has a step at both ends of the short side under the diaphragm in the gap, the counter electrode and the side surface of the step have a concave structure, and vibrates from the distance between the convex part that becomes the beam of the diaphragm and the upper surface of the step. By adopting a configuration in which the distance between the convex portion serving as a beam of the plate and the counter electrode is far, even when the gap is narrowed, sufficient displacement of the diaphragm can be obtained for droplet discharge, and the diaphragm is used as the counter electrode. Driving can be performed without touching, and thus the driving frequency can be improved.

Next, a fourth embodiment of the liquid discharge head according to the present invention will be described with reference to FIGS. 13 is an explanatory plan view of the electrode side surface of the diaphragm of the head, and FIG. 14 is an explanatory sectional view taken along line X1-X1 in FIG.
Here, convex portions 43 for preventing adhesion and improving durability between the diaphragm side and the fixed electrode side are formed between the convex portions 41 which are beams for adjusting rigidity in the present invention. In addition, the convex part 41 which becomes a beam for rigidity adjustment has a length L2 along the diaphragm short side direction, and is arranged side by side along the diaphragm long side direction.

  For the protrusion 43 for preventing sticking and improving durability, the diaphragm and the fixed electrode are in contact with each other only at the portion of the protrusion 43, and the vibration plate rigidity, gap length and protrusion dimensions ( Plane dimensions and height). In addition, in the vicinity of the convex portion 43 for preventing sticking and improving durability, it is possible to improve durability by adopting a configuration in which no voltage is applied between the diaphragm electrode and the fixed electrode. In this case, since no voltage is applied to the portion, the force for deforming the diaphragm (electrostatic force between the diaphragm and the fixed electrode) becomes small (compared when the gap length and the applied voltage are the same). Therefore, from this point, there is a demand for the size of the projections to be as small as possible and the number to be reduced.

  In this example, by adjusting the rigidity of the diaphragm around the convex portion 43 for preventing adhesion / improving durability by the convex portion 41 serving as a beam for adjusting rigidity, the convex portion 43 for preventing adhesion / durability is improved. The dimensions are small and the number is small. Of course, the electrostatic force that causes the diaphragm to bend between the diaphragm electrode and the fixed electrode does not occur in the portion of the convex part 41 for adjusting the diaphragm rigidity, but is fixed to the convex part 41 that serves as a beam for adjusting the diaphragm rigidity. By appropriately setting the arrangement and dimensions of the projections 43 for preventing and improving durability, the total force to deform the diaphragm can be increased (compared when the gap length and applied voltage are the same). .

  The formation of the projection 41 serving as a diaphragm for adjusting the rigidity of the diaphragm and the projection 43 for preventing sticking and improving durability can be dealt with only by changing the design of the photomask for patterning. Can be made without.

  Here, the difference between the convex portion 41 serving as a beam for adjusting diaphragm rigidity and the convex portion 43 for preventing sticking and improving durability is described in Table 1.

Next, a fifth embodiment of the liquid ejection head according to the present invention will be described with reference to FIGS. 15 is an explanatory plan view of the electrode side surface of the diaphragm of the head, and FIG. 16 is an explanatory sectional view taken along line X1-X1 in FIG.
Here, convex portions 43 for preventing adhesion and improving durability between the diaphragm side and the fixed electrode side are formed between the convex portions 41 which are beams for adjusting rigidity in the present invention. In addition, the convex part 41 which becomes a beam for rigidity adjustment has a length L3 (the convex parts 41 at both ends in the long side direction are shorter than the length L3) along the long side direction of the diaphragm, and the long side direction of the diaphragm Are arranged side by side.

  Even if comprised in this way, the effect similar to 4th Embodiment is acquired.

  In addition to the configurations of the second to fifth embodiments, it is possible to obtain high rigidity with a thin diaphragm by uniformly forming convex portions as beams on the entire surface of the simple diaphragm.

  A liquid discharge head according to a sixth embodiment of the present invention will be described with reference to FIGS. 17 is a sectional explanatory view in the longitudinal direction of the liquid chamber along the X1-X1 line in FIG. 18, and FIG. 18 is a sectional explanatory view in the lateral direction in the liquid chamber along the Y1-Y1 line in FIG.

  Here, the groove 52 on the fixed electrode 14A side corresponding to the convex portion 51 serving as a beam on the diaphragm 12 side does not penetrate the fixed electrode forming layer, and the fixed electrode forming layer remains at the bottom portion of the groove 52. Yes. With such a configuration, the effect of increasing the rigidity is smaller than in the first embodiment, but on the other hand, the area of the portion to which the voltage is applied (the portion where the diaphragm electrode and the fixed electrode face each other) is relatively Therefore, when compared with the same gap length and the same voltage, the diaphragm deformation force (electrostatic attractive force between the diaphragm and the fixed electrode) can be made larger than that in the first embodiment.

An example of the manufacturing process on the process electrode side of the sixth embodiment will be described with reference to FIG.
As shown in FIG. 19A, a positive resist 55 is applied on the fixed electrode forming layer 24 formed on the insulating film 22 and exposed using a fixed electrode patterning mask 56.

  As shown in FIG. 20A, the fixed electrode patterning mask 56 includes a transparent portion 56a corresponding to a groove portion for separation into fixed electrodes, and a translucent portion corresponding to a groove (dent) forming the convex portion 51. 56b. The transmittances of the transparent part 56a and the translucent part 56b are as shown in FIG. Further, the transmittance, exposure amount, and development time (in the next step) of the translucent area 56b are appropriately set according to the sensitivity characteristics of the resist.

  Further, as shown in FIG. 21, the fixed electrode patterning mask 56 has a non-resolved glass area (transparent area) 56c with a lattice-shaped remaining portion (light-shielding portion) with respect to the chrome area (light-shielding area) 56d. It is also possible to use a translucent part 56b that is arranged so as to be. In this case, the transmittance can be set by the aperture ratio. Further, a negative resist and a mask with reversed contrast may be used.

  Returning to FIG. 19B, by performing development processing, on the fixed electrode formation layer 24, the resist 55 corresponding to the opening 55a from which the resist 55 has been completely removed corresponding to the dividing grooves and the convex portion are formed. As a result, a resist pattern having a portion 55b that is thinned but not opened is obtained.

  As shown in FIG. 19C, by performing etching under conditions where both the resist 55 and the fixed electrode forming layer 24 are etched, a portion corresponding to the opening 55a for the fixed electrode separation groove is formed as a fixed electrode. In the portion corresponding to the portion 55b corresponding to the convex portion 51, the resist 55 is reduced and disappears in the portion corresponding to the portion 55b corresponding to the convex portion 51. Depending on the selection ratio between the resist 55 and the fixed electrode formation layer 24, all of the separation groove portions are etched at this stage.

  Thereafter, the etching proceeds, and the etching time is set appropriately, whereby a separation groove 24a is formed in the fixed electrode forming layer 24 and separated into the fixed electrode 24A and the like as shown in FIG. In the electrode 24A, the portion 24b corresponding to the convex portion 51 on the diaphragm side is etched halfway, and the insulating film 23 is formed thereon, whereby the groove 52 is formed. Thereafter, although not shown, the convex portion 51 is formed by forming a sacrificial layer or a constituent layer of the diaphragm 12 and performing etching.

  In addition, although not shown, a step (first step) of forming a separation groove portion in the electrode forming layer by etching (first step), a step of etching the resist and opening a recess corresponding to the convex portion of the resist mask (second step) Step), the electrode forming layer is etched to complete the groove separation, and the three-step etching of the step (third step) for forming the depression corresponding to the convex portion can be performed.

  In any case, when the processing is continuously performed in the same etching chamber, the process time is hardly increased and the cost is hardly increased as compared with the conventional process.

  A liquid discharge head according to a seventh embodiment of the present invention will be described with reference to FIGS. 22 is a sectional explanatory view in the longitudinal direction of the liquid chamber along the line X1-X1 in FIG. 23, FIG. 23 is a sectional explanatory view in the lateral direction in the liquid chamber along the line Y1-Y1 in FIG. 22, and FIG. FIG. 25 is an enlarged cross-sectional explanatory view taken along line Y4-Y4 in FIG. 22.

  Here, the groove 62 on the fixed electrode 14A side corresponding to the convex portion 61 to be a beam formed on the diaphragm 12 penetrates the fixed electrode 14A, and further on the insulating layer 22 which is a base layer formed by laminating the fixed electrode 14A. Are formed in the same pattern.

  In this case, in order to prevent the unevenness of the coating thickness from occurring during spin coating of the resist or the wetted film 31, the fixed electrode forming layer 24 is formed on almost the entire surface of the actuator substrate 1 (electrode The lead-out part 33, the electrode lead-out part 34, etc.) remain.

  In addition, the manufacturing process is the same as that of the first embodiment except that after the fixed electrode forming layer 24 is etched in the processing process of the fixed electrode 14A, the number of processes for continuously etching the base insulating layer 22 with the same mask is increased. The same can be done. The point where the fixed electrode forming layer 24 is left over almost the entire surface of the actuator substrate 1 can be performed without any change in the process only by changing the mask for patterning the fixed electrode.

  By adopting such a configuration, the depth of the groove 62 becomes deeper and the height of the convex portion 61 on the diaphragm side can be increased, so that the diaphragm rigidity can be greatly increased at that portion. . On the other hand, in the manufacturing process, the base layer of the fixed electrode is continuously etched with the same mask as the fixed electrode forming layer, so that the number of processes is increased and the cost is hardly increased.

  Further, as shown in FIGS. 24 and 25, the electrode wiring 33 and the fixed electrode forming layer 24 left under the external electrical connection portion 34 are connected to the adjacent electrode wiring 33 and the external electrical connection. By separating the fixed electrode formation layer 24 between the portions 34, the stray capacitance is reduced.

  In the present embodiment, the surface of the actuator substrate is flattened by leaving the fixed electrode forming layer over substantially the entire surface of the actuator substrate (electrode extraction portion, electrode extraction portion, etc.). Contrary to the fixed electrode processing step of the embodiment, by using a photomask in which the portion corresponding to the groove 62 corresponding to the convex portion 61 is transparent and the fixed electrode separation groove portion is translucent, there is no increase in the number of steps. Further, it is possible to achieve flattening by forming a recess in the underlying layer corresponding to the convex portion 61 and forming a groove in the underlying layer and etching only the electrode forming layer in the fixed electrode separation groove.

Next, a seventh embodiment of the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 26 is an explanatory perspective view showing an example of the liquid discharge head.
The liquid discharge head 90 is integrally provided with a liquid storage portion (tank) 93 that supplies, for example, a recording liquid as a liquid to a liquid discharge head portion 92 having a nozzle 91. Thereby, a tank integrated liquid discharge head can be obtained.

Next, an example of an image forming apparatus including the liquid ejection apparatus according to the present invention including the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 27 is a schematic configuration diagram for explaining the overall configuration of the mechanism section of the apparatus.
This image forming apparatus is a line type image forming apparatus equipped with a recording head composed of a full line type head having a nozzle row (with nozzles 4 arranged) longer than the print area width of the medium.

  This image forming apparatus is, for example, four full-line liquid ejection heads that eject droplets of each color of black (K), cyan (C), magenta (M), and yellow (Y). The recording heads 101k, 101c, 101m, and 101y (which are referred to as “recording heads 101” when colors are not distinguished) are provided, and each recording head 101 is mounted on a head holder (not shown) with the surface on which the nozzles 4 are formed facing downward. In addition, a maintenance / recovery mechanism 102 for maintaining / recovering the head performance corresponding to each recording head 101 is provided, and during the head performance maintenance operation such as purge processing and wiping processing, the recording head 101 is maintained / recovered. The mechanism 102 is moved relatively so that the capping member constituting the maintenance / recovery mechanism 102 faces the nozzle surface of the recording head 101. .

  Here, the recording head 101 is arranged to eject droplets of each color in the order of black, cyan, magenta, and yellow from the upstream side in the paper conveyance direction, but the arrangement and the number of colors are not limited to this. Further, as the line-type head, one or a plurality of heads provided with a plurality of nozzle rows for discharging droplets of each color at predetermined intervals can be used, and a recording liquid cartridge for supplying a recording liquid to the head and the head. Can be integrated or separated.

  The paper feed tray 103 includes a bottom plate 105 on which the paper 104 is placed and a paper feed roller (half-moon roller) 106 for feeding the paper 104. The bottom plate 105 can rotate around a rotation shaft 109 attached to the base 108 and is urged toward the sheet feeding roller 106 by a pressure spring 110. A separation pad (not shown) made of a material having a large friction coefficient, such as an artificial leather or a cork material, is provided to face the sheet feeding roller 106 to prevent double feeding of the sheet 104. In addition, a release cam (not shown) for releasing the contact between the bottom plate 105 and the paper feed roller 106 is provided.

  Guide members 110 and 111 for guiding the paper 104 are provided to feed the paper 104 fed from the paper feed tray 103 between the transport roller 112 and the pinch roller 113.

  The conveyance roller 112 is rotated by a driving source (not shown) and conveys the fed paper 104 toward the platen 115 disposed facing the recording head 101. As long as the platen 115 can maintain the gap between the recording head 101 and the paper 104, a rigid structure may be used, or a conveyance belt may be used.

  On the downstream side of the platen 115, a paper discharge roller 116 for discharging the paper 104 on which an image is formed and a spur 117 facing the paper discharge roller 116 are arranged, and the paper 104 on which an image is formed by the paper discharge roller 116 is discharged. The paper is discharged to the paper tray 118.

  Further, on the side opposite to the paper discharge tray 118, a manual feed tray 121 for manually feeding the paper 104 and a paper feed roller 122 for feeding the paper 104 placed on the manual feed tray 121 are arranged. The sheet 104 fed from the manual feed tray 121 is guided by the guide member 111 and fed between the transport roller 112 and the pinch roller 113.

  In this image forming apparatus, in the standby state, the release cam pushes down the sheet feeding tray 103 bottom plate 105 to a predetermined position, and releases the contact between the bottom plate 105 and the sheet feeding roller 106. In this state, when the transport roller 112 is rotated, this rotational driving force is transmitted to the sheet feeding roller 106 and a release cam (not shown) by a gear or the like (not shown), and the release cam is separated from the bottom plate 105 and moved to the bottom plate 105. The sheet feeding roller 106 and the sheet 104 come into contact with each other, the sheet 104 is picked up as the sheet feeding roller 106 rotates, and sheet feeding is started, and the sheets are separated one by one by a separation claw (not shown).

  Then, the sheet 104 is guided by the guide members 110 and 111 by the rotation of the feeding roller 106 and is fed between the conveying roller 112 and the pinch roller 113, and the sheet 104 is fed onto the platen 115 by the conveying roller 112. Thereafter, the trailing edge of the sheet 104 is released from contact with the D-cut portion of the sheet feeding roller 106 and is conveyed onto the platen 115 by the conveying roller 112. Note that. A conveyance rotation pair may be provided between the sheet feeding roller 106 and the conveyance roller 112 as an auxiliary.

  In this way, an image is formed by ejecting droplets from the recording head 1 on the sheet 104 conveyed on the platen 115, and the sheet 104 on which the image is formed is placed on a sheet discharge tray 118 by a sheet discharge roller 116. The paper is ejected. Note that the paper conveyance speed and the droplet discharge timing during image formation are controlled by a control unit (not shown).

  As described above, the image forming apparatus is equipped with the liquid discharge head capable of adjusting the rigidity of the diaphragm according to the present invention, and is equipped with a liquid discharge head capable of performing stable liquid discharge. Therefore, an image forming apparatus that can cope with high image quality and high-speed recording can be obtained.

Next, another example of the image forming apparatus including the liquid discharge apparatus according to the present invention including the liquid discharge head according to the present invention will be described with reference to FIGS. FIG. 28 is a schematic configuration diagram for explaining the overall configuration of the mechanism portion of the apparatus, and FIG. 29 is a plan view for explaining a main portion of the mechanism portion.
This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held in the main scanning direction by main and sub guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 201A and 201B. The main scanning motor that does not move is moved and scanned in the direction indicated by the arrow (carriage main scanning direction) in FIG. 29 via the timing belt.

  The carriage 233 has recording heads 234a and 234b (which are composed of liquid ejection heads according to the present invention for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). When not distinguished, it is referred to as “recording head 234”). A nozzle row composed of a plurality of nozzles is arranged in the sub-scanning direction orthogonal to the main scanning direction, and is mounted with the ink droplet ejection direction facing downward.

  Each of the recording heads 234 has two nozzle rows. One nozzle row of the recording head 234a has black (K) droplets, the other nozzle row has cyan (C) droplets, and the recording head 234b has one nozzle row. One nozzle row ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets.

  The carriage 233 is equipped with head tanks 235a and 235b (referred to as “head tank 35” when not distinguished) for supplying ink of each color corresponding to the nozzle rows of the recording head 234. The sub tank 235 is supplementarily supplied with ink of each color from the ink cartridge 210 of each color via the supply tube 36 of each color.

  On the other hand, as a paper feeding unit for feeding the paper 242 stacked on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feeding) that separates and feeds the paper 242 one by one from the paper stacking unit 241. A separation pad 244 made of a material having a large coefficient of friction is provided opposite to the sheet roller 243 and the sheet feeding roller 243, and the separation pad 244 is urged toward the sheet feeding roller 243 side.

  In order to feed the sheet 242 fed from the sheet feeding unit to the lower side of the recording head 234, a guide member 245 for guiding the sheet 242, a counter roller 246, a conveyance guide member 247, and a tip pressure roller. And a conveying belt 251 which is a conveying means for electrostatically attracting the fed paper 242 and conveying it at a position facing the recording head 234.

  The conveyor belt 251 is an endless belt, and is configured to wrap around the conveyor roller 252 and the tension roller 253 so as to circulate in the belt conveyance direction (sub-scanning direction). In addition, a charging roller 256 that is a charging unit for charging the surface of the transport belt 251 is provided. The charging roller 256 is disposed so as to come into contact with the surface layer of the conveyor belt 251 and to rotate following the rotation of the conveyor belt 251. The transport belt 251 rotates in the belt transport direction of FIG. 29 when the transport roller 252 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the transport belt 251, a paper discharge roller 262, and a paper discharge roller 263 are provided. A paper discharge tray 203 is provided below the paper discharge roller 262.

  A duplex unit 271 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 271 takes in the paper 242 returned by the reverse rotation of the transport belt 251, reverses it, and feeds it again between the counter roller 246 and the transport belt 251. The upper surface of the duplex unit 271 is a manual feed tray 272.

  Further, as shown in FIG. 29, in the non-printing area on one side of the carriage 233 in the scanning direction, the state of the nozzles of the recording head 234 is maintained, and the head according to the present invention including recovery means for recovery is maintained. A maintenance / recovery mechanism 281 as a device is arranged.

  The maintenance / recovery mechanism 281 includes cap members (hereinafter referred to as “caps”) 282a and 282b (hereinafter referred to as “caps 282” when not distinguished) for capping each nozzle surface of the recording head 234, and nozzle surfaces. A wiper blade 283 that is a blade member for wiping the ink, and an empty discharge receiver 284 that receives liquid droplets for discharging the liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid. ing.

  As shown in FIG. 29, in the non-printing area on the other side in the scanning direction of the carriage 233, idle discharge is performed to discharge liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. An ink recovery unit (empty discharge receiver) 288, which is a liquid recovery container for receiving liquid droplets at that time, is arranged, and this ink recovery unit 288 is provided with an opening 289 along the nozzle row direction of the recording head 234 and the like.

  In this image forming apparatus configured as described above, the sheets 242 are separated and fed one by one from the sheet feeding tray 202, and the sheet 242 fed substantially vertically upward is guided by the guide 245, and is conveyed to the conveyor belt 251 and the counter. It is sandwiched between the rollers 246 and conveyed, and further, the leading end is guided by the conveying guide 237 and pressed against the conveying belt 251 by the leading end pressing roller 249, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately applied to the charging roller 256, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 251 alternates, 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 sheet 242 is fed onto the conveyance belt 251 charged alternately with plus and minus, the sheet 242 is attracted to the conveyance belt 251, and the sheet 242 is conveyed in the sub scanning direction by the circumferential movement of the conveyance belt 251.

  Therefore, by driving the recording head 234 according to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 242 has reached the recording area, the recording operation is finished and the paper 242 is discharged onto the paper discharge tray 203.

  Even such a serial type image forming apparatus is equipped with a liquid discharge head capable of performing stable liquid discharge with a liquid discharge head capable of adjusting the rigidity of the diaphragm according to the present invention. The density can be increased, and an image forming apparatus capable of high image quality and high-speed recording can be obtained.

  In the above embodiment, the liquid ejection apparatus according to the present invention has been described as an example applied to an image forming apparatus having a printer configuration. However, the present invention is not limited to this. For example, an image forming apparatus such as a printer / fax / copier multifunction machine is used. It can also be applied to. Further, the present invention is also applicable to a liquid discharge apparatus and an image forming apparatus that use a liquid other than a recording liquid, for example, a liquid discharge head that is used in a liquid discharge apparatus or an image forming apparatus that discharges a DNA sample, resist, pattern material, or the like as described above. can do. In addition to the liquid discharge head, the electrostatic actuators that make up the liquid discharge head are not only micropumps and optical devices (light modulation devices), but also microswitches (microrelays) and multi-optical lens actuators (light Switch), micro flow meter, pressure sensor, and the like.

FIG. 3 is an exploded perspective view of the liquid discharge head according to the first embodiment of the present invention. It is a plane explanatory view of the head. It is a plane explanatory view of the electrode side surface of the diaphragm of the head. FIG. 3 is a cross-sectional explanatory view taken along line X1-X1 in FIG. FIG. 3 is a cross-sectional explanatory view taken along line X2-X2 of FIG. FIG. 5 is a partially enlarged cross-sectional explanatory diagram of FIG. 4. FIG. 3 is a cross-sectional explanatory view taken along line Y1-Y1 of FIG. FIG. 3 is a cross-sectional explanatory view taken along line Y2-Y2 of FIG. It is a plane explanatory view of the electrode side surface of the diaphragm of the liquid ejection head concerning a 2nd embodiment of the present invention. It is a plane explanatory view of the electrode side surface of the diaphragm of the liquid ejection head concerning a 3rd embodiment of the present invention. It is explanatory drawing of the bending shape in case a diaphragm rigidity is uniform. It is explanatory drawing of the bending shape in case the rigidity of a diaphragm center part is high and it is low at both ends. It is a plane explanatory view of the electrode side surface of the diaphragm of the liquid ejection head concerning a 4th embodiment of the present invention. It is an expanded sectional explanatory view which follows the X1-X1 line | wire of FIG. It is a plane explanatory view of the electrode side surface of the diaphragm of the liquid ejection head concerning a 5th embodiment of the present invention. FIG. 16 is an enlarged cross-sectional explanatory view taken along line X1-X1 of FIG. FIG. 19 is a cross-sectional explanatory view in the longitudinal direction of a liquid chamber along the X1-X1 line in FIG. 18 of a liquid ejection head according to a sixth embodiment of the present invention. FIG. 18 is an explanatory cross-sectional view in the lateral direction of the liquid chamber along the Y1-Y1 line of FIG. 17. It is a cross-sectional explanatory drawing similarly used for description of the formation process of the groove | channel on the fixed electrode side. It is explanatory drawing explaining an example of the mask for fixed electrode formation used at the formation process. It is explanatory drawing explaining the other example of the mask for fixed electrode formation similarly. FIG. 24 is a cross-sectional explanatory view in the longitudinal direction of the liquid chamber along the X1-X1 line of FIG. 23 of the liquid discharge head according to the seventh embodiment of the present invention. FIG. 23 is a cross-sectional explanatory view in the lateral direction of the liquid chamber along the Y1-Y1 line of FIG. FIG. 23 is an enlarged cross-sectional explanatory view along the Y3-Y3 line of FIG. 22. FIG. 23 is an enlarged cross-sectional explanatory view along the Y4-Y4 line of FIG. 22. FIG. 10 is an explanatory perspective view for explaining a liquid ejection head according to an eighth embodiment of the present invention. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present invention including a liquid ejection apparatus including a liquid ejection head according to the present invention. FIG. 5 is a schematic configuration diagram illustrating another example of an image forming apparatus including a liquid ejection device according to the present invention. Similarly it is principal part plane explanatory drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Actuator board | substrate 2 ... Channel board 3 ... Nozzle plate 4 ... Nozzle 5 ... Nozzle communication path 6 ... Liquid chamber (discharge chamber)
DESCRIPTION OF SYMBOLS 7 ... Fluid resistance part 8 ... Common liquid chamber 12 ... Diaphragm 13 ... Air gap 14A ... Fixed electrode 41, 51, 61 ... Convex part 42, 52, 62 ... Groove 90 ... Liquid discharge head 101 ... Recording head (liquid Discharge head)
234... Recording head (liquid ejection head)

Claims (7)

A diaphragm that forms a wall surface of a flow path that communicates with a nozzle that discharges droplets, and an electrode that is opposed to the diaphragm via a gap formed by sacrificial layer etching. The diaphragm is deformed by electrostatic force. In the liquid discharge head that discharges the droplets by mechanical restoring force,
A liquid discharge head, wherein a convex portion serving as a beam of the diaphragm is formed on a surface of the diaphragm with respect to the electrode, and a groove for escaping the convex portion of the diaphragm is formed on the electrode side. .   2. The liquid ejection head according to claim 1, wherein the groove formed on the electrode side penetrates a layer forming the electrode and does not enter an underlayer on which the electrode is stacked. Liquid discharge head.   2. The liquid ejection head according to claim 1, wherein the groove formed on the electrode side penetrates the layer forming the electrode, and further enters the base layer on which the electrode is stacked. A liquid discharge head.   4. The liquid discharge head according to claim 1, wherein the layer forming the electrode remains over substantially the entire area of the base layer on which the electrode is laminated. .   5. The liquid discharge head according to claim 1, wherein a liquid storage unit that supplies liquid to the liquid discharge head is integrated. 6.   6. A liquid discharge apparatus for discharging liquid droplets from a liquid discharge head, wherein the liquid discharge head is the liquid discharge head according to claim 1. 6. An image forming apparatus for forming an image by mounting a liquid discharge head for discharging droplets, wherein the liquid discharge head is the liquid discharge head according to claim 1. .