JPH0920008A - INKJET HEAD, METHOD FOR MANUFACTURING THE SAME, AND PRINTING DEVICE HAVING THE SAME - Google Patents

Abstract

(57) [Abstract] [Purpose] Efficient driving, stable ejection can be obtained, reliability of printing result is high, variation in ejected ink amount among nozzles is small, and printing quality is good and easy. An inkjet head and a method for manufacturing the same are provided. A nozzle 4, an ink flow path communicating with the nozzle 4, a vibrating plate 5 provided in a part of the flow path, an individual electrode 21 facing the vibrating plate 5, and a vibrating plate 5. The gas layer 9 and the insulating layer 19 are provided between the individual electrodes 21, and the common electrode 17
In an inkjet head that applies a drive voltage between the individual electrodes 21 and the vibrating plate 5 by electrostatic force to eject ink droplets from the nozzles 4, the vibrating plate 5 has an area of
An ink jet head which is formed so as to have a smaller area than the individual electrode 21, and is arranged so that the contour of the diaphragm 5 vertically projected onto the individual electrode 21 is included in the contour of the individual electrode 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head for printing by ejecting ink droplets from nozzles, and more particularly to the construction of a drive section thereof.

[0002]

2. Description of the Related Art Ink jet printers have many advantages such as extremely low noise during recording, high-speed printing, and the use of inexpensive plain paper with a high degree of freedom of ink. Among them, the so-called ink-on-demand method, which discharges ink droplets only when recording is necessary, is currently the mainstream because it does not require collection of ink droplets unnecessary for recording.

A conventional ink-on-demand type ink jet head is, for example, JP-A-2-289351. This is to insert a viscoelastic ferroelectric between the first electrode and the second electrode and apply a voltage to the first electrode and the second electrode to drive them to eject ink droplets. there were.

[0004]

However, in the prior art, when the relative position of the second electrode facing the first electrode is displaced for manufacturing reasons, the electric field leaks when the inkjet head is driven. However, there is a problem that the charge cannot be sufficiently accumulated, the force for electrostatically attracting the diaphragm is insufficient, and the power for ejecting ink cannot be obtained. That is, there is a problem that the ejection efficiency of the inkjet head is reduced.

Further, when the flow passages and the vibrating plate are arranged at a high density, the deterioration of the ejection efficiency due to the relative displacement of the first electrode and the second electrode in the above-mentioned manufacturing is a serious problem. .

Further, if the ejection efficiency of ink from the nozzles varies among the nozzles in the same head and varies, the amount of ink ejected from each nozzle is different, and good printing quality cannot be obtained. It was

In addition, if the processing and assembling accuracy in manufacturing is improved in order to solve the above problems, there are problems that the apparatus for manufacturing the head becomes large and the yield of non-defective products is reduced.

The object of the present invention is to solve the problems of the prior art as described above, to obtain an efficient and stable ejection at the time of driving an ink jet head, and to obtain a reliable print result.
It is an object of the present invention to provide an inkjet head and a method for manufacturing the inkjet head, which has a small variation in the amount of ejected ink among the nozzles, has good printing quality, and can be easily manufactured.

[0009]

An ink jet head according to the present invention includes a nozzle, an ink flow path communicating with the nozzle, a vibration plate provided in a part of the flow path, and a vibration plate facing the vibration plate. In the ink jet head, which has an individual electrode provided as described above, applies a drive voltage between the individual electrode and the vibrating plate, deforms the vibrating plate by electrostatic force, and ejects ink droplets from the nozzle. The area of the plate is smaller than the area of the individual electrode, and the contour of the diaphragm vertically projected on the individual electrode is arranged to be included in the contour of the individual electrode. Is characterized by.

Further, in a preferred mode of the present invention, it is composed of at least three laminated substrates including a first substrate on which the diaphragm is formed and a second substrate on which the individual electrodes are formed.

When the shape of the diaphragm and the individual electrode is substantially rectangular, the ratio (b−b) of one side a of the outline of the diaphragm to one side b of the corresponding contour of the individual electrode.
The preferable range of a) / b is 4% or more and 15% or less.

Further, in the method for manufacturing an ink jet according to the present invention, at least the step of forming the ink flow path or a part thereof and the vibration plate on the first substrate, and the step of forming the vibration plate on the second substrate. The step of forming the individual electrodes, and the outline of the diaphragm vertically projected on the individual electrodes being included in the outline of the individual electrodes,
It is characterized in that it has three steps of bonding the substrate and the second substrate.

Further, the printing apparatus of the present invention comprises the above-mentioned ink jet head and a driving means for applying a driving voltage between the individual electrode of the ink jet head and the vibration plate to deform the vibration plate by electrostatic force. And

[0014]

When a driving voltage for driving the head is applied to the common electrode and the individual electrodes of the ink jet head of the present invention, electric charges are instantaneously accumulated in the common electrode and the individual electrodes, and the vibrating plate is placed on the individual electrode side due to electrostatic pressure. It flexes while eliminating the gas in the gas layer. At the same time, the ink in the pressure chamber of the ink flow path is sucked from the orifice.

When the application of the drive voltage is stopped and the respective electrodes are made to have the same potential, the accumulated charges disappear through the respective electrodes, and the restoring force of the diaphragm causes the diaphragm to remove the ink in the ink flow path. While restoring. A part of the removed ink is ejected as an ink droplet from a nozzle, adheres to a surface of a print medium such as paper, permeates, solidifies, or reacts with the print medium to form a pixel, and printing is performed by repeating this control.

As described above, the positional relationship between the diaphragm and the individual electrodes is such that the outline of the diaphragm vertically projected onto the individual electrodes is
Since it is arranged so as to be included in the contour of the individual electrode, even if the relative position between the individual electrode and the diaphragm is deviated in the manufacturing process of the inkjet, the electric field working between the diaphragm and the individual electrode is unlikely to leak. . Therefore, when a drive voltage is applied between the diaphragm and the individual electrodes, a desired electric field always acts on the diaphragm, and stable ink ejection can be expected.

[0017]

EXAMPLES The present invention will be described below based on examples.
FIG. 1 is an enlarged cross-sectional view of an ink flow path and a drive unit of an inkjet head according to an embodiment of the present invention.

As shown in the drawing, the structure of the ink jet head of one embodiment of the present invention has a structure in which a cover glass 3, a first substrate 1 and a second substrate 2 are laminated and joined.

The first substrate 1 is made of a conductive material and has a flow path including a nozzle 4, a pressure chamber 6, an orifice 7 and a reservoir 8 connected to each other. Further, the first substrate 1 is provided with a diaphragm 5, an insulator layer 19, and a common electrode 17 made of a thin film layer formed by sputtering an electrode material such as Pt. The second substrate 2 is made of an insulating material, has a void 9 (gas layer) formed therein, and is provided with an individual electrode 21 made of a conductive thin film.

The nozzle 4, the pressure chamber 6, the orifice 7 and the reservoir 8 communicate with each other to form an ink flow path.

The diaphragm 5, the common electrode 17, the air layer 9, the insulator layer 19, and the individual electrode 21 constitute an actuator section.

The ink flow path is formed by joining the cover glass 3 and the first substrate 1, and the actuator portion is formed by joining the first substrate 1 and the second substrate 2, respectively.

The individual electrode 21 and the vibrating plate 5 are opposed to each other in parallel with the air layer 9 and the insulating layer 19 interposed therebetween. The area of the diaphragm 5 is formed smaller than the area of the individual electrode 21, and one side a of the diaphragm 5 is also smaller than one side b of the corresponding individual electrode 21. That is, by projecting the contour of the diaphragm 5 in the deformation direction of the diaphragm (vertical direction in the drawing), the shadow (projection surface) formed on the individual electrode is included in the contour of the individual electrode 21. In addition, the size relationship and the positional relationship between the diaphragm 5 and the individual electrode 21 are determined.

The ink jet head is composed of a plurality of ink flow paths and an actuator section. Other ink flow paths and actuators in the same head have the same configuration.

A tube 33 is connected to the opening of the reservoir 8 of the ink jet head and is connected to an ink tank (not shown). Ink is supplied from the ink tank to the reservoir 8 through the tube 33, and the ink flow path is filled with ink.

In the actuator section, the individual electrode 21
A positive (+) potential is applied to the diaphragm 5. That is, the drive voltage is applied. At this time, positive charges are accumulated in the diaphragm 5, and conversely, negative charges are accumulated in the individual electrode 21. As a result, an electrostatic attraction force acts between the diaphragm 5 and the individual electrode 21, the diaphragm 5 is attracted to the individual electrode 21, the diaphragm 5 is bent and deformed, and the individual electrode 21 is interposed via the insulating layer 19. Abut. Since the insulating layer 19 is interposed, the diaphragm 5 and the individual electrode 21 are not short-circuited and insulation is maintained. As a result, the diaphragm 5 is held in contact with the individual electrode 21.

The electrostatic attraction force acting on the diaphragm 5 at this time is proportional to the projected area of the diaphragm 5 on the individual electrode 21 and the electric field strength. If the distance between the diaphragm 5 and the individual electrode 21 is constant, that is, if the diaphragm 5 and the individual electrode 21 are arranged in parallel, the electric field strength at the initial stage of attraction is constant on the diaphragm 5. Therefore, in this case, the electrostatic attraction force acting on the diaphragm 5 is proportional only to the projected area of the diaphragm 5 with respect to the individual area 21.

From the state where there is a potential difference between the individual electrode 21 and the diaphragm 5, the individual electrode 21 and the diaphragm 5 are brought to the same potential. That is,
The application of the voltage is stopped and the diaphragm 5 and the individual electrode 21 are set to the same potential. At this time, the electric charges accumulated in the vibration plate 5 and the individual electrodes 21 are rapidly lost, the vibration plate 5 is released from the force of the electric field, and is restored to the ink flow path side by its own restoring force.

By constructing the actuator portion of the ink jet head as in the example shown in FIG. 1, the vibrating plate 5 can vibrate in the gas layer 9 at high speed. Also, since no ferroelectric is used in this configuration,
No electric charge remains in the electrode portion and the actuator. Accumulation and discharge of charges are easily and quickly performed.

Further, since the individual electrode 21 is arranged so as to include the projection surface of the diaphragm 5 onto the individual electrode 21, even if the relative position deviation between the individual electrode 21 and the diaphragm 5 occurs slightly. There is no electric field leakage, and a constant electric field always acts on the diaphragm.

Details regarding the positional and dimensional relationships between the diaphragm 5 and the individual electrodes of the ink jet head in the embodiment of the present invention shown in FIG. 1 will be described below with reference to FIGS. 2 and 3.

FIG. 2 is a schematic plan view of one flow path of the ink jet head of the embodiment of the present invention shown in FIG. 3 is a schematic cross-sectional view of the actuator section taken along the line AA in FIG.

The individual electrodes 21 are the dimensions a and a'of the diaphragm 5 and the dimensions b of the individual electrodes 21 shown in FIG.
It is provided so that the relationship of b'is a <b and a '<b'.

Since the individual electrode 21 and the diaphragm 5 are arranged in the above-described position and dimensional relationship, the individual electrode 2
1 and the vibration plate 5 are displaced from each other by (b−a) / 2 to the left or right of that shown in FIG. 2 or FIG. There is no difference in the electrostatic attraction force between the diaphragm 5 and the individual electrode 21 with the actuator having no deviation. This is because the projected area of the diaphragm 5 with respect to the individual area 21 is the same in both cases.

In other words, with respect to the mutual alignment of the first substrate 1 and the second substrate 2, in manufacturing (b-
a) / 2 has an allowable range. Therefore,
It is necessary to set the odd shapes and dimensions of the diaphragm 5 and the individual electrode 21 while paying attention so that the dimensional relationship (ba) does not have a negative value. At the same time, it means that the larger (ba) is set, the easier the manufacturing of the actuator portion of the inkjet head of the present invention will be. (B-
If the value of a) is too large, the adjacent individual electrodes 21
The actual value of this is
Of the substrate 1 and the second substrate 2 and the nozzle pitch (the distance between the adjacent nozzles determined based on the resolution of the pixels to be printed). Similarly, the dimensional relationships a ′ and b ′ are determined based on the above-mentioned viewpoints.

In the preferred embodiment, the nozzle pitch is 7
0.6 μm, each shape dimension is a = 4 mm, b = 4.
184 mm, a ′ = 102 μm, b ′ = 106.2 μm
Set to. At this time, (b−a) /b=4.3%,
(B'-a ') / b' = 4.1%. That is, if the shape and size of the individual electrode 21 are larger than the diaphragm 5 by about 4% or more, the current manufacturing capacity can be sufficiently covered.

In another embodiment, the nozzle pitch is 8
0 μm, a ′ = 364.8 μm, b ′ = 420 μm
m. At this time, (b'-a ') / b' = 13.1
%. That is, the shape and size of the individual electrode 21 is equal to
An ink jet head capable of printing an image with a sufficiently practical resolution can be manufactured up to about 15% larger than the above.

Next, the operation of the ink jet head of the present invention according to the driving example will be described below. FIG. 4, FIG. 5 and FIG. 6 are side sectional views of the ink jet head in the embodiment of the present invention. An example of the operation of the inkjet head of the present invention will be described below with reference to these drawings.

In FIG. 4, the ink jet head is
The ink flow path is filled with ink and is in a standby state when ejecting ink. From the standby state, the diaphragm 5
When a voltage is applied to the individual electrode 21 to generate a potential difference, an electrostatic attraction force acts on the diaphragm 5 and the individual electrode 21,
The diaphragm 5 is attracted to the individual electrode 21.

FIG. 5 shows a state in which ink is supplied from the reservoir 8 to the pressure chamber 6 in the direction of arrow B by the vibrating plate 5 attracted to the individual electrodes 21 by applying a voltage.

As shown in FIG. 6, when the timing at which the ink is sufficiently supplied is selected, the application of the voltage is stopped, and the vibration plate 5 and the individual electrode 21 are made to have the same potential, the charge disappears promptly and the vibration plate 5 is discharged. Is released from the force of the electric field and restores to the pressure chamber 6 side by its own restoring force. At this time, the ink droplet 104 is ejected from the nozzle hole 4 by the pressure generated in the pressure chamber 6. At the same time, the ink in the pressure chamber 6 passes through the orifice 7 in the direction of arrow C and is discharged to the reservoir 8.

After that, the vibration of the ink in the ink flow path is attenuated and converged by the flow path resistance, and the standby state shown in FIG. 4 is again established so that the next ink can be ejected.

The ejected ink droplet 104 adheres to and penetrates the surface of the print medium such as a paper surface to form a pixel. A matrix of pixels is printed on a print medium by selectively repeatedly controlling and driving a plurality of actuators, and information is printed.

Next, the structure and manufacturing method of the ink jet head of the present invention will be described in detail according to the embodiments.

FIG. 7 is an exploded perspective view of an ink jet head in one embodiment of the present invention, which is a partial sectional view. FIG. 8 is a perspective view of an assembled inkjet head of an inkjet head according to an embodiment of the present invention.

The ink jet head 10 of this embodiment has a laminated structure in which three substrates 1, 2, 3 having the structure described in detail below are laminated and joined.

The intermediate first substrate 1 is a silicon substrate, and a plurality of nozzle grooves 1 are formed on the surface of the substrate 1 in parallel from one end at equal intervals so as to form a plurality of nozzle holes 4.
1, a concave portion 12 communicating with each nozzle groove 11 and constituting a pressure chamber 6 which is a pressure generating portion having a diaphragm 5 as a bottom wall, and an orifice 7 provided at the rear portion of the concave portion 12. A narrow groove 13 for the ink inlet, which is to be
Each of the pressure chambers 6 has a concave portion 14 that constitutes a reservoir 8 that is an ink supply portion for supplying ink.

The substrate 1 of the ink jet head shown in the embodiment of the present invention is formed by anisotropically etching single crystal silicon. Anisotropic etching is etching performed by utilizing the fact that the etching rate differs depending on the etching direction. In this embodiment, single crystal silicon (10
The etching rate of the (0) plane is about 4 compared to the (111) plane.
The nozzle groove 11, the recess 12, the narrow groove 13, and the recess 14 are formed by utilizing the fact that they are 0 times faster. Each of the inner nozzle groove 11 and the narrow groove 13 is a V-shaped groove composed of a (111) surface with a slow etching rate. That is,
The nozzle groove 11 and the narrow groove 13 are formed in a triangular sectional shape. The nozzle groove 11 has a width of 60 μm, and the thin groove 13 has three flow passages arranged in parallel and has a width of 55 μm. Further, the recesses 12 and 14 are trapezoidal grooves having a bottom surface of (100) plane and side surfaces of (111) plane. Recess 1
The groove depths of 2 and 14 are determined by adjusting the etching time. On the other hand, since the nozzle groove 11 and the thin groove 13, which are V-shaped grooves, are composed of only the (111) surface having a slow etching rate, the depth thereof is determined only by the groove width regardless of the etching time.

The nozzle groove 11 and the thin groove 13 are regions in the ink flow passage that are sensitive to characteristics such as the amount and speed of ejected ink, and the highest processing accuracy is required. In the embodiment of the present invention, these high processing precision required parts are formed by using the surface having a slow etching rate, and by anisotropic etching, flow paths of different dimensions can be processed with high accuracy. Makes it possible to get. Therefore, it is possible to easily obtain the substrate 1 having high dimensional accuracy by applying the single crystal material, particularly the single crystal Si, as the material of the substrate 1.

After forming the flow path in the substrate 1, an oxide film having a thickness of 0.07 to 0.15 μm is formed on the surface by thermal oxidation. As a result, the insulating layer 19 is attached to the surface of the diaphragm 5. By forming the insulating layer 19 by thermal oxidation of Si, which is the material of the substrate 1, it is possible to form and apply an insulating layer that is dense and has high quality with few defects.

Borosilicate glass is used for the second substrate 2, and a gas layer 9 is formed below the vibrating plate 5 of the first substrate 1 to mount the individual electrodes facing the vibrating plate 5. Is provided. The gas layer 9 is formed by the bonding of the second substrate 2, and an ITO conductive film is sputtered by 0.1 μm at each position corresponding to the vibration plate 5 on the second substrate 2, so that the vibration layer 5 is almost formed. IT in the same shape
An O pattern is formed to serve as the individual electrode 21. The individual electrode 21 has a lead portion 22 and a terminal portion 23.

The upper third substrate 3 bonded to the upper surface of the first substrate 1 is made of borosilicate glass, like the second substrate 2. By joining the third substrate 3, the nozzle hole 4, the pressure chamber 6, the orifice 7, the reservoir 8 and the filter 51 are formed.

The material of the substrate 1 may be any material such as glass or ceramics as long as the dimensions of the flow path formed on the substrate 1 and the flatness and surface roughness of the substrate 1 can be secured. When glass is used as the material of the substrate 1, it is convenient to form the channel by isotropic etch etching, and it is relatively easy to secure dimensional accuracy.

Assembly by bonding the first substrate 1, the second substrate 2 and the third substrate (cover glass) 3 will be described below.

Positioning marks (not shown) provided on the respective substrates so that the positions of the vibrating plate 5 of the first substrate 1 and the positions of the individual electrodes 21 of the second substrate 2 correspond and correspond to each other. ) Is used to align and fix the positions of the substrate 1 and the substrate 2. Since the performance of the inkjet head cannot be ensured unless the mutual positions of the first substrate 1 and the second substrate 2 are accurately aligned within an allowable range, precision of the alignment of the marks is required. To align these positions with each other,
Use a special precision alignment device such as an aligner.

Next, the first substrate 1 and the second substrate 2 are anodically bonded at a temperature of 340 ° C. and a voltage of 800 to 900 V is applied, and the first substrate 1 and the third substrate 3 are bonded under the same conditions. Join and assemble the inkjet head. After the anodic bonding, the thickness of the gas layer 9 formed between the vibration plate 5 and the individual electrode 21 on the second substrate 2 is 0.2 μm in this embodiment.
There is. The insulating layer 19 is configured so that the individual electrode 21 and the diaphragm 5 do not come into contact with each other even if the gas layer 9 is eliminated and disappears during driving. If the oxide film as the insulating layer is too thick, it causes a weak electric field, while if it is too thin, dielectric breakdown tends to occur due to repeated electric field stress. In this embodiment, the thickness of this oxide film is 0.09 to 0.13 μm.

Next, the actuator section is hermetically sealed.
The airtight sealing of the actuator portion is performed to prevent foreign matter from entering the actuator from the outside.
The airtight sealing is performed by filling and hardening an appropriate resin between the individual electrode wiring portion 22 and the substrate 1. In manufacturing, the gas in the gas layer 9 is determined by the environment and atmosphere in which this hermetic sealing is performed. By carrying out the hermetic sealing in an arbitrary gas atmosphere or environment, the gas inside the gas layer 9 can be controlled in production.

Dry air is hermetically sealed in the gas layer 9 to form an air layer. The gas layer 9 is constituted by enclosing a relatively stable gas such as nitrogen or argon gas in addition to air. Nitrogen or the like is preferably used as a gas that is relatively easily available, and inert gas such as argon gas is preferably used as a gas for keeping the inside of the actuator stable without causing chemical reaction such as oxidation.

After the ink jet head is assembled as shown in FIG. 8, the drive circuit 40 is connected between the common electrode 17 and the terminal portion 23 of the individual electrode 21 by the FPC 49 to form the ink jet printer. Ink 103
Goes through the filter from the ink tank (not shown)
Is supplied to the inside of the substrate 1 and is filled in the reservoir 8, the pressure chamber 6 and the like. Then, the ink in the pressure chamber 6 is ejected as ink droplets 104 from the nozzle holes 4 when the inkjet head 10 is driven, and is printed on a recording medium such as recording paper.

This embodiment shows an example of the edge eject type in which ink droplets are ejected from the nozzle holes provided in the end portion of the substrate, but ink droplets are ejected from the nozzle holes provided in the upper surface portion of the substrate. It may be a face eject type.

Next, the features of the present invention will be described in more detail below. 9 and 10 are schematic plan views showing the shapes and positions of the diaphragm 5 and the individual electrodes 21. In the present invention,
The individual electrode 21 is arranged so as to include the projection surface of the diaphragm 5 onto the individual electrode 21. Assuming that the area of the projection surface of the diaphragm 5 on the individual electrode 21 is the effective area of the diaphragm 5, in the present invention, the effective area is always the area of the diaphragm 5 and the electric field that generates the attractive force is The working area is always maximum and constant.

In FIG. 9, each of the individual electrodes 21 and the diaphragm 5 has a rectangular shape, and the vertical and horizontal lengths of the individual electrodes 21 are larger than the corresponding vertical and horizontal lengths of the opposed diaphragms 5, respectively. Is also long (large), and the diaphragm 5 is configured to be located at the center position 51 of the individual electrode 21. In this case, even if the relative position of the diaphragm 5 with respect to the individual electrode 21 is slightly deviated, the above-mentioned effective area is constant regardless of the positional deviation.

Next, the structure, operation and effect of the present invention when the shapes of the individual electrode 21 and the diaphragm 5 are different from those of the above-described embodiments will be described. In FIG. 10, reference numeral 221 indicates the outer shape of the individual electrode. 222 is a wiring part of the individual electrode. Reference numeral 52 indicates the outer shape of the diaphragm. Since the other configurations of the ink flow path and the actuator section of the inkjet head are the same as those described above, they are omitted.

(A) shows an example in which the diaphragm 52 and the individual electrode 221 are circular in shape. In this case, the outer dimension, that is, the diameter of the individual electrode 221 is equal to
Is set larger than the outer dimension of the diaphragm 52, that is, the diameter of the diaphragm 52. As a result, even when the shapes of the diaphragm 52 and the individual electrode 221 are circular, according to the configuration of the present invention, the individual electrode 2 of the diaphragm 52 is
Even if the relative position to 21 is slightly deviated, the above-mentioned effective area is constant irrespective of the positional deviation, and the action and effect of always keeping the electrostatic attraction force acting on the vibration plate 52 at the maximum at the time of driving are constant. It turns out that they are the same.

By forming the diaphragm 52 into a circular shape,
It is possible to make the stress generated at the time of suction and contact with the vibration plate 52 most uniform, suppress the generation of high-order vibration, and most efficiently increase the generated pressure in the pressure chamber 6. This makes it possible to manufacture an inkjet head with high efficiency.

In (b), the shape of the diaphragm 52 is square,
This is an example when the shape of the individual electrode 221 is circular. In this case, the outer dimension or diameter of the individual electrode 221 is set to be larger (longer) than the outer dimension of the diaphragm 52 corresponding to the opposing diaphragm 52, that is, the diagonal length of the diaphragm 52. Accordingly, even when the shapes of the diaphragm 52 and the individual electrode 221 are different from each other, according to the configuration of the present invention, even if the relative position of the diaphragm 52 to the individual electrode 221 is slightly deviated, the above-mentioned effective area is It can be seen that the action is the same regardless of the positional deviation, and the action and effect that the electrostatic attraction force acting on the diaphragm 52 during driving is always kept at the maximum.

Thus, the first substrate 1 and the second substrate 2
The shape is determined by the processing method of
Even when it is difficult to make the outer shapes of the individual electrode 221 and the individual electrode 221 the same, it is possible to obtain the effect by applying the configuration of the present invention while the shapes of the diaphragm 52 and the individual electrode 221 are different. is there. As such an example, the flow path of the first substrate 1 and the diaphragm 52 are formed by anisotropic etching of an anisotropic material, and the second substrate 2 is formed by isotropic etching. To be

(C) shows an example in which the diaphragm 52 and the individual electrode 221 have a rectangular shape. In this case, the external dimensions, that is, the vertical and horizontal lengths of the individual electrodes 221 are set to be larger than the external dimensions of the diaphragm 52 corresponding to the opposing diaphragm 52, that is, the vertical and horizontal lengths of the diaphragm 52, respectively. Similar to the cases shown in (a) and (b), even when the diaphragm 52 and the individual electrode 221 have a rectangular shape, the same operation and effect can be obtained according to the configuration of the present invention. I understand.

In this way, the diaphragm 52 and the individual electrode 221
By configuring both of the shapes to be rectangular, it is possible to dispose highly efficient and high-density ink flow paths and actuators on the substrate, and it is ideal for the production of inkjet heads with high pixel density. Have

FIG. 11 shows the ink jet head 10 described above.
FIG. 3 is a schematic view showing an embodiment of an inkjet recording apparatus of the present invention equipped with the. A platen 300 conveys the recording paper 105, and an ink tank 301 stores ink therein, and supplies ink to the inkjet head 10 via an ink supply tube 306. Reference numeral 302 denotes a carriage, which connects the inkjet head 10 to the recording paper 105.
Move in the direction perpendicular to the transport direction of. Carriage 3
It is possible to print arbitrary characters or images on the recording paper 105 by ejecting the ink 104 from the inkjet head 10 at appropriate times by moving the driving circuit 40 while moving 02.

Reference numeral 303 denotes a pump that sucks ink through the cap 304 and the waste ink collection tube 308 and discharges it when performing a recovery operation when the ink jet head 10 is defectively ejected or refilling the ink. It has a function of collecting in the ink reservoir 305.

An example of application of the above-described ink jet head of the present invention to a recording apparatus is a permanent type recording apparatus which does not require replacement of the ink jet head. The permanent type recording apparatus is very convenient because the user only needs to replenish the consumed ink, and the printing cost is relatively low.

In this embodiment, only the ink jet head 10 is arranged on the carriage 302, but the present invention is not limited to this, and the ink tank may be arranged on the carriage.

FIG. 12 shows the ink jet head 10 described above.
FIG. 8 is a schematic view showing another embodiment of the ink jet recording apparatus of the present invention in which is mounted. A head unit 401 integrally includes the inkjet head 10, an ink tank, and an ink supply member that connects the inkjet head 10 and the ink tank. The head unit 401 is mounted on the carriage 302 and moved in a direction orthogonal to the conveyance direction of the recording paper 105. By arbitrarily ejecting the ink 104 from the inkjet head 10 while moving the carriage 302, it is possible to print arbitrary characters or images on the recording paper 105. The head unit 401 is a so-called disposable type in which the ink tank is integrated with the head (a type in which the inkjet head is replaced when the ink in the ink tank becomes empty).

The disposable type head does not require a suction pump or a mechanism or member for storing the recovered ink, and the entire recording apparatus can be easily and small-sized.

[0076]

As described above, according to the present invention, even when the relative positions of the individual electrodes facing the diaphragm are displaced due to manufacturing reasons, the electric field leaks when the inkjet head is driven. Since it does not occur, the force for electrostatically attracting the vibrating plate can always be made constant at the maximum, and the power for ink ejection can also be made always constant at the maximum. . That is, there is an effect that it is possible to provide an inkjet head in which the ejection efficiency of ink is good and constant.

Further, it is possible to arrange the flow passages and the vibrating plate at a high density without lowering the ejection efficiency due to the relative displacement between the first substrate and the second substrate, and to increase the pixel density for printing. This has the effect of providing an inkjet head capable of high-quality printing.

Further, there is an effect that the ejection efficiency of ink from the nozzles does not differ between the nozzles in the same head, the amount of ink ejected from each nozzle is uniform, and good print quality is obtained.

In addition, since a high degree of processing and assembling accuracy in manufacturing the ink jet head is not required, the apparatus for manufacturing the head does not become large and the mass yield is not lowered, and the manufacturing is easy. It also has the effect that there is.

As described above, according to the present invention, the problems of the prior art are solved, the efficiency is high when the ink jet head is driven, stable ejection is obtained, the reliability of the printing result is high, and the ejected ink amount is high. It is possible to provide an inkjet head which has little variation among nozzles, has good printing quality, and can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional side view of an inkjet head according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of an inkjet head according to an embodiment of the present invention.

FIG. 3 is a sectional view of an actuator portion of an inkjet head according to an embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view of the inkjet head according to the embodiment of the present invention during standby.

FIG. 5 is an enlarged cross-sectional view of the inkjet head according to the embodiment of the present invention during operation.

FIG. 6 is a sectional side view of the inkjet head according to the embodiment of the present invention during operation.

FIG. 7 is an exploded perspective view of the inkjet head according to the embodiment of the present invention.

FIG. 8 is a perspective view of an inkjet head according to an embodiment of the present invention.

FIG. 9 is a schematic plan view of an actuator portion of an inkjet head according to an embodiment of the present invention.

FIG. 10 is a schematic plan view of an actuator unit of an inkjet head according to an embodiment of the present invention.

FIG. 11 is a schematic diagram of a printer equipped with an inkjet head according to an embodiment of the present invention.

FIG. 12 is a schematic diagram of a printer equipped with an inkjet head according to an embodiment of the present invention.

[Explanation of symbols]

 1 ... 1st board 2 ... 2nd board 5 ... diaphragm 6 ... pressure chamber (pressure generation part) 19 ... insulating layer 21 ... individual electrode 22 ... individual Electrode wiring section

Claims (6)

[Claims] 1. A nozzle, an ink flow path communicating with the nozzle, a vibration plate provided in a part of the flow path, and an individual electrode facing the vibration plate with a predetermined gap, In an inkjet head that ejects ink droplets from the nozzles by applying a driving voltage between an individual electrode and the diaphragm and deforming the diaphragm by an electrostatic force, the area of the diaphragm is the area of the individual electrode. An ink jet head, which is formed so as to be smaller, and is arranged such that a contour of the diaphragm vertically projected on the individual electrode is included in a contour of the individual electrode. 2. The ink jet head according to claim 1, comprising at least three stacked substrates including a first substrate on which the diaphragm is formed and a second substrate on which the individual electrodes are formed. An inkjet head characterized in that. 3. The ink jet head according to claim 1, wherein the diaphragm and the individual electrode have a substantially rectangular shape, and a side a of the contour of the diaphragm and a side b of the contour of the individual electrode corresponding to the side a. An ink jet head having a ratio (ba) / b of 4% or more. 4. The inkjet head according to claim 1, wherein the shape of the diaphragm and the individual electrode is substantially rectangular, and one side b of the contour of the individual electrode corresponding to one side a of the contour of the diaphragm. Ratio (ba) / b is 15%
An inkjet head characterized by the following. 5. The method of manufacturing an inkjet according to claim 2, wherein at least the ink flow path or a part thereof and the vibration plate are formed in the first substrate, and the second substrate. First, the step of forming the individual electrode and the outline of the diaphragm vertically projected on the individual electrode are included in the outline of the individual electrode.
A method for manufacturing an inkjet head, comprising the step of joining the substrate of 1) and the second substrate. 6. A printing apparatus comprising: the inkjet head according to claim 1; and a drive unit that applies a drive voltage between an individual electrode of the inkjet head and a diaphragm to deform the diaphragm by electrostatic force. .