JP3389732B2 - INK JET RECORDING APPARATUS AND INK JET HEAD MANUFACTURING METHOD - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-on-demand type ink jet recording apparatus and an ink jet head manufacturing method.

[0002]

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

A conventional ink-on-demand type ink jet head is, for example, the ink jet head disclosed in Japanese Patent Publication No. 62-8316. In this head, a filter provided in the ink supply section of the head is formed at the same time as the flow path by photoetching. This was to obtain an inkjet head having a built-in filter capable of stably ejecting ink.

[0004]

The filter for preventing foreign matter from entering the flow channel needs to have a cross-sectional size of the opening smaller than that of the nozzle or the supply port of the flow channel. In the conventional inkjet head, the filter is formed at the same time as the nozzle of the flow path and the supply port by isotropic etching, so that the depth is also formed to be the same. For this reason, the size of foreign matter that has passed through the filter may be the same as that of the nozzle or supply port of the flow path.
There is a high probability that the nozzles of the flow path and the supply port are clogged, and there is a problem that it is not possible to completely prevent the nozzles and the supply port of the flow path from being clogged.

Further, if the filter is simply formed inside the head as in the conventional ink jet head, it has the following problems and is difficult to put into practical use.

The ink supply unit communicates with a plurality of flow paths to distribute and supply the ink to the ink flow paths. At the same time, the pressure due to the ink backflow from the ink supply path when the ink is ejected from the nozzle is relaxed.

When the inertance of the filter is large, the pressure due to the ink backflow from the ink supply passage when the ink is ejected from the nozzle cannot be sufficiently absorbed and alleviated, which causes the pressure rise in the ink supply portion, and the ink flow passage. There is a problem in that pressure interference occurs between them and ink is ejected from the nozzles (hereinafter, non-driving nozzles) of the flow passages in which the pressure generating portion of the ink flow passage is not operated. (Generation of crosstalk) When the flow path resistance of the filter becomes large, it becomes impossible to sufficiently supply the ink from the ink supply section to the ink flow path, and the ink ejection amount decreases or air is taken in from the nozzle. Therefore, there is a problem that stable ink ejection cannot be performed.

Further, even when the ink capacity of the ink supply section from the ink supply path of the ink flow path to the filter is small, the pressure is not sufficiently absorbed and buffered, and the ink is the same as when the filter has a large inertance. There is a problem in that pressure interference occurs between the ink flow paths via the supply section, and ink is ejected from the nozzles of the flow path in which the pressure generating section of the flow path is not operating.

In any of these cases, the printed matter of a printer equipped with an ink jet head may be missing pixels, may cause stains on the printed matter, or may lead to erroneous reading, leading to a decrease in printing reliability, or a printed result such that the printed result is not clear. It causes troubles such as lowering the rank.

Further, when forming a filter using an isotropic material such as glass, the etching ratio during etching is not stable, and it is difficult to easily and accurately form a filter to manufacture an ink jet head. There was a problem that was.

The present invention has been made in order to solve the above problems, and it is possible to prevent clogging of a flow path due to the inflow of foreign matter, and to manufacture a highly reliable ink jet recording apparatus and ink jet head without missing dots. The purpose is to provide a method.

It is another object of the present invention to provide an ink jet head and an ink jet recording apparatus which are capable of stable ink ejection without pressure interference between ink flow paths and insufficient supply of ink and which can obtain good print quality.

Another object of the present invention is to obtain an ink jet head and an ink jet recording apparatus which can be easily manufactured, are inexpensive, and have high dimensional accuracy and quality.

[0014]

An ink jet recording apparatus of the present invention comprises a plurality of nozzle holes, an ejection chamber communicating with each of the nozzle holes, an independent ejection chamber, and a common ink chamber communicating with the ejection chamber. An orifice that connects the common ink chamber and the ejection chamber, a filter including a plurality of grooves formed on the supply port side for supplying ink to the common ink chamber, and a pressure generating unit that generates pressure in each of the ejection chambers. In an ink jet recording apparatus having an ink jet head including: and a driving unit that selectively drives the pressure generating unit to eject an ink droplet from the nozzle, each of a plurality of grooves forming the filter is The filter has a cross-sectional area smaller than the cross-sectional area of the nozzle hole, and the inertance of the filter is 1/5 or less of the inertance from the nozzle hole to the orifice. Characterized in that there.

[0015]

Further, it is preferable that the flow path resistance of the filter is one fourth or less of the flow path resistance from the nozzle to the orifice. Further, each groove forming part of the discharge chamber, part of the common ink chamber, part of the orifice, and a plurality of grooves forming the filter are anisotropically formed on the first surface. A crystalline substrate and a lid substrate that is joined to the first surface of the anisotropic crystalline substrate and that forms the discharge chamber, the common ink chamber, and the filter together with the grooves may be provided.

A preferred form of the common ink chamber is characterized in that at least one wall surface is made flexible.

The method of manufacturing an inkjet according to the present invention is the same as the method of manufacturing an inkjet head described above,
A part of the ejection chamber, a part of the common ink chamber, and each groove forming a part of the orifice are provided in the first anisotropic crystal substrate.
A step of anisotropically etching the surface, a step of attaching the pressure generating means to the discharge chamber, and a step of bonding the lid substrate to the first surface of the anisotropic crystal substrate to thereby remove the edge of each groove. Sealing, and forming the discharge chamber, the common ink chamber, and the orifice, the anisotropic etching step, further, the inertance of the filter is the inertance from the nozzle hole to the orifice. Of 5
A plurality of grooves constituting the filter are formed by anisotropic etching on the first surface of the anisotropic crystal substrate so as to be one-tenth or less.

In order to form an actuator for driving the vibration plate provided on a part of the wall surface of the discharge chamber, an electrode is further formed on the insulator substrate, and the electrode is
Bonding the insulating substrate to a second surface of the anisotropic material substrate opposite to the first surface so as to face the diaphragm with a predetermined gap, or the discharge chamber of the anisotropic material substrate. A step of attaching a piezoelectric element that deforms the vibration plate to the back side of the.

[0020]

According to the present invention, the ink supplied to the ink jet head is supplied through the filter provided at the ink supply port and is stored in the common ink chamber. The ink stored in the common ink chamber is distributed and supplied to each ejection chamber via each ink supply passage. The pressure generating means is driven based on the recording data to apply pressure to the ink in the ejection chamber, and ink droplets are ejected from the nozzle holes communicating with the ejection chamber.

Since the ink or the cleaning liquid for the ink flow path at the time of manufacture is supplied through the filter provided at the ink supply port, foreign matters larger than the open area of the filter contained in these liquids are filtered. Are prevented by the above, so that they do not enter the ink flow path downstream of the ink supply port. Since the filter opening area is provided smaller than the cross-sectional area of the nozzle hole, each ink supply passage, etc., the foreign matter that has passed through the filter is discharged from the nozzle, and the narrow nozzle and the like are not clogged with the foreign matter. Since the ink flow path does not become clogged, it is possible to obtain a highly reliable head without causing printing defects.

Further, since the inertance of the filter is set to 1/5 or less of the inertance of the ink flow path from the nozzle hole to the supply passage, the pressure generated in the ejection chamber of the driven nozzle (driving nozzle) The resulting pressure rise in the common ink chamber is reduced.

As a result, the pressure generated in the driving nozzle is transmitted to the non-driving nozzle, and the undesirable phenomenon of ejecting ink from the non-driving nozzle (pressure interference between ejection chambers, crosstalk) does not occur.

Further, since the flow path resistance of the filter is set to 1/4 or less of the flow path resistance of the ink flow path from the nozzle hole of the head to the supply path, it is sufficient from the ink supply port to the downstream ink flow path. It is possible to supply various types of ink, and supply shortage does not occur. Even if the head is driven at high speed, print density does not drop, and dot missing printing defects due to unstable ejection do not occur.

Further, if at least one wall surface of the common ink chamber is made flexible, the pressure generated in the ejection chamber of the drive nozzle is sufficiently absorbed and buffered, and crosstalk due to pressure interference between the ejection chambers is also caused. Lost.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an exploded perspective view of an ink jet head in one embodiment of the present invention, which is a partial sectional view. Although this embodiment shows an example of an edge eject type in which ink droplets are ejected from a nozzle hole provided at the end of the substrate, a face eject ejecting ink droplets from the nozzle hole provided in the upper surface of the substrate. You can type. 2 is a perspective view of the entire assembled inkjet head, and FIG. 3 is a cross-sectional side view of an ink flow path portion of the inkjet head. Embodiments of the present invention will be described below with reference to the drawings.

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 at equal intervals from one end so as to form a plurality of nozzle holes 4.
1, a concave portion 12 communicating with each nozzle groove 11 and constituting a discharge 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
It has a concave portion 14 which constitutes a reservoir 8 which is an ink supply portion for supplying ink to each ejection chamber 6, and a filter groove 52 which constitutes a filter 51 provided at the rear portion of the concave portion 14.

In the present embodiment, the gap between the diaphragm 5 and the electrode arranged opposite thereto, that is, the gap portion 1
A length G of 6 (see FIG. 3, hereinafter referred to as “gap length”).
So that there is a difference between the depth of the recess 15 and the thickness of the electrode,
The space holding means is composed of the vibration chamber recess 15 formed in the second substrate 2. Further, as another example, the recess may be formed on the lower surface of the first substrate 1. Here, the recess 15
The depth is set to 0.3 μm by etching. The pitch of the nozzle grooves 11 is 0.509 mm and the width thereof is 60 μm.

Regarding the provision of the common electrode 17 on the first substrate 1, it is important that the work function of the metal material of the semiconductor and the electrode is large or small. In this embodiment, titanium is used as the common electrode material. Although platinum or chromium is used as an undercoat and gold is used as the undercoat, the invention is not limited to this embodiment, and when the substrate 1 is a P-type semiconductor, the work function of the common electrode material is larger than that of the common electrode material. Any material can be used as long as it is an N-type semiconductor, and any material can be used as long as the work function of the common electrode material is smaller than that of the common electrode material.

Borosilicate glass is used for the lower second substrate which is bonded to the lower surface of the first substrate 1.
In the lower part of the vibrating plate 5, there is provided a recess 15 which constitutes the vibrating chamber 9 for mounting the electrode. The vibration chamber 9 is formed by bonding the second substrate 2, and the IT is provided at each position corresponding to the vibration plate 5 on the second substrate 2.
An O conductive film is sputtered by 0.1 μm, and an ITO pattern is formed in the same shape as the vibration plate 5 to form 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 as with the second substrate 2. By joining the third substrate 3, the nozzle hole 4, the discharge chamber 6, the orifice 7, the reservoir 8 and the filter 51 are formed. And in this reservoir 8,
A convex portion 19 is provided to have strength so that the concave portion is not crushed when the first substrate and the third substrate are joined. In the present embodiment, the filter 51 also serves as an ink supply port, is connected to the connection pipe 32, and is connected to an ink tank (not shown) via the tube 33.

Next, the first substrate 1 and the second substrate 2 are anodically bonded by applying a temperature of 300 to 500 ° C. and a voltage of 500 to 1000 V, and under the same conditions, the first substrate 1 and the third substrate 3 And the ink jet head is assembled as shown in FIG. After joining the anode, the gap length G formed between the diaphragm 5 and the individual electrode 21 on the second substrate 2 is equal to the recess 1
5 and the thickness of the individual electrode 21, which is 0.2 μm in this embodiment. Further, a silicon oxide film is formed on the surface of the diaphragm 5 of the substrate 1 by thermal oxidation,
Even if the individual electrode 21 and the diaphragm 5 come into contact with each other, the short circuit does not occur. If the thermal oxide film as the insulating film is too thick, it causes a weak electric field. On the other hand, if it is too thin, dielectric breakdown is likely to occur due to repeated electric field stress. In this embodiment, the thickness of this thermal oxide film is 0.13 μm.

After the ink jet head is assembled as shown in FIG. 2, 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
Is supplied to the inside of the first substrate 1 from an ink tank (not shown) through the filter 51, and the reservoir 8 and the discharge chamber 6
And so on. The ink in the ejection chamber 6 is
As shown in FIG. 2, when the inkjet head 10 is driven, the ink droplets 104 are ejected from the nozzle holes 4 as
It is printed on the recording paper 105.

FIG. 4 is a partially detailed enlarged plan view of the substrate 1. The substrate 1 of the inkjet 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, the fact that the etching rate of the single crystal silicon (100) plane is about 40 times or more higher than that of the (111) plane is utilized, and the nozzle groove 11, the concave portion 12, the narrow groove 13, the concave portion 14 and The filter groove 52 is formed. The inner nozzle groove 11, the narrow groove 13 and the filter groove 5
Reference numeral 2 is a V-shaped groove composed of a (111) plane with a slow etching rate. That is, the nozzle groove 11, the narrow groove 13, and the filter groove 52 are formed in a triangular cross-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.
The width of the filter groove 52 is 50 μm, and the recess 1
54 are connected to each other in parallel. Further, the recesses 12 and 14 are trapezoidal grooves having a bottom surface of (100) plane and side surfaces of (111) plane. The groove depth of the recesses 12 and 14 is determined by adjusting the etching time. On the other hand, since the nozzle groove 11, the thin groove 13, and the filter groove 51, which are V-shaped grooves, are formed only by 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, the thin groove 13 and the filter groove 52 are parts sensitive to the characteristics such as the amount and speed of ejected ink in the ink flow path, 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.

As in the above-described dimensional configuration example of the present embodiment, by configuring the width of the filter groove 52 to be narrower than the nozzle groove 11 and the narrow groove 13, the ink flow path formed by the third substrate bonding. The opening cross-sectional area of the inner filter 51 is configured to have the smallest cross-sectional area in the flow path cross-sectional area. All the foreign substances that block the nozzle holes 4 and the orifices 7 are blocked by the filter holes 51 and do not enter the ink flow path, so that printing defects such as dot dropouts are less likely to occur, and the reliability of the inkjet head can be secured. Furthermore, since it is possible to prevent clogging of nozzle holes and clogging of orifices during manufacturing, it is possible to improve the yield rate and obtain a head that is easy to manufacture in large quantities.

FIGS. 5A to 5C are side sectional views of the ink jet head in the embodiment of the present invention.
In particular, the state in which the diaphragm is deformed from the standby state until ink is ejected will be described. In addition, FIGS. 6A to 6C respectively show FIGS.
It is a schematic diagram showing the state of the voltage applied between the diaphragm and the electrode in the state of (c). An example of the operation of the inkjet head of the present invention will be described below with reference to these drawings.

FIG. 5A is a side sectional view of the ink jet head in the standby state, and FIG. 6A is a schematic view showing the potential between the diaphragm 5 and the individual electrode 21 at that time. .

At this time, the ink jet head is in a standby state when ink is ejected because the ink flow path is filled with ink. Next, as shown in FIG. 6B, when a voltage is applied to the diaphragm 5 and the individual electrode 21 from the standby state to generate a potential difference, the diaphragm 5 and the individual electrode 21 are
The electrostatic attraction force acts on the diaphragm 5, and the diaphragm 5 is attracted to the individual electrode 21. At this time, as shown in FIG. 5B, the pressure inside the ejection chamber 6 is reduced by the diaphragm 5 sucked by the individual electrode 21, and ink is supplied from the reservoir 8 to the ejection chamber 6 in the direction of arrow B. . At the same time, the meniscus 102 formed on the nozzle 4 is also sucked toward the discharge chamber 6. Next, as shown in FIG. 6C, the timing at which the ink is sufficiently supplied is selected, the voltage application is stopped, and the electric charges stored in the diaphragm 5 and the individual electrode 21 are discharged.
As shown in FIG. 5C, the diaphragm 5 is released from the force of the electric field and is restored to the discharge 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 ejection chamber 6. At the same time, the ink in the ejection 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 by the flow path resistance and converges, and the standby state again shown in FIG. 5A is reached, and the next ink can be ejected.

In the driving method described above, the diaphragm is not deformed in the standby state, and the pressure inside the discharge chamber is once reduced by deforming the diaphragm during driving, and immediately after that, the force applied to the diaphragm is applied. It is a method of releasing and increasing the pressure to eject ink droplets (so-called pulling ejection), but in the standby state the diaphragm is always deformed and the diaphragm is opened only when ink is ejected. A method (so-called pushing) may be used. According to the method by the hitting ejection shown in the example, it is possible to increase the amount of ejected ink and drive with excellent frequency characteristics of the ejected ink amount. In any case, the operation and effect of the present invention are the same even if the driving force and the driving method are different.

Next, the flow path constant of the ink jet head in this embodiment will be described. The ink flow path of the inkjet head has various properties due to the viscosity and density of the ink, depending on the cross-sectional area perpendicular to the streamline of the ink, the circumferential length thereof, and the length of the flow path.

The inertance M is defined as follows: ρ is the density of ink, L is the length of the flow path, and S is the cross-sectional area perpendicular to the flow line of the flow path.
It is shown by the following formula.

[0044]

[Equation 1]

The inertance M is the resistance to the ink volume acceleration, and the larger the inertance M, the greater the resistance to the force such as generated pressure and the acceleration.

When the viscosity of the ink is η and the cross-sectional circumference of the flow path is T, the flow path resistance R is

[0047]

[Equation 2]

It is shown by. This represents the resistance to ink volume velocity. The greater the flow path resistance R, the greater the resistance to the ink flow.

Further, when the speed of sound in the ink is c and the volume of the ink flow path is W, the capacity C of the ink is

[0050]

[Equation 3]

It is shown by. The ink volume C indicates the deformation resistance of the ink, and the larger the ink volume C, the easier the ink is to deform. That is, the ability to buffer pressure is large.

In the ink jet head, the flow channel constants of the ink flow channels that are formed are balanced and set while adjusting these to ensure stable ink ejection.

The reservoir 8 and the filter 51 also have the inertance, the flow path resistance, and the ink capacity described above, like the ink flow path. In the embodiment of the present invention, the driving method described with reference to FIGS. 5 and 6 does not cause crosstalk (pressure interference between ink flow paths) in which ink droplets are ejected from non-driving nozzles or insufficient supply of ink. In addition, the flow path constants such as the inertance of the reservoir 8 and the filter 51, the flow path resistance, and the ink capacity are set with respect to the flow path constant of the ink flow path.

Hereinafter, an example of setting the flow channel constants of the reservoir 8 and the filter 51 will be described in detail.

FIG. 7 is a plan view of an embodiment of the present invention.
The flow channel constants of the reservoir 8 and the filter 51 will be described based on this figure.

First, the ink droplets 104 are ejected by driving the actuators attached to the ejection chamber 6 from the nozzles of nk out of the nozzles of the ink jet head having n nozzles. The following description will be made on the assumption that the state is set. (K is the number of non-driving nozzles) In this embodiment, the flow channel constants of the reservoir 8 and the filter 51 are set so that ink droplets are not ejected from the non-driving nozzles due to crosstalk in this state.

At the same time when the ink droplet 104 is ejected from the nozzle hole 4, a part of the ink flows back from the orifice 7 to the reservoir 8. At this time, w is the amount of ink ejected once per drive nozzle, and Ua is the volume velocity of ink flowing back from the orifice 7 of one drive nozzle to the reservoir 8. Further, let the inertance of the entire flow path of the discharge section from the nozzle 4 to the orifice 7 configured in parallel with n be Ma and the flow path resistance be Ra, and the inertance of the flow path of the supply section composed of the reservoir 8 and the filter 51. And the flow path resistance are M
If f and Rf are given, these can be expressed as follows.

[0058]

[Equation 4]

Here, Lf is the length of the filter 51, Sf
Indicates the cross-sectional area of the opening of the filter, and Tf indicates the cross-sectional perimeter of the opening of the filter.

[0060]

[Equation 5]

Here, l is the length of the entire flow path of the discharge portion from the nozzle 4 to the orifice 7, and S (x) is the length of one flow path at any position x from the nozzle 4 to the orifice 7. In the cross-sectional area, T (x) is the cross-sectional perimeter of one flow path at any position x from the nozzle 4 to the orifice 7.

Further, the ratio of the inertance Ma of the entire discharge section and the inertance Mf of the supply section is set to α = Mf / Ma. In the state of FIG. 8, the pressure increase δPfk of the reservoir 8 when the ink droplet 104 is ejected is

[0063]

[Equation 6]

It becomes t indicates time. At this time, the amount of ink ejected from one nozzle that is not driven (non-driven nozzle), that is, the amount wc of crosstalk that occurs as a result of mutual interference between the ink flow paths, is determined by the pressure increase δPfk in the reservoir 8 being nM.
Since the value divided by a is integrated twice,

[0065]

[Equation 7]

It becomes Where β is a constant determined by the balance between the nozzle side inertance and flow path resistance of the ink flow path and the orifice side inertance and flow path resistance, and the ratio of the amount w of ink ejected from the nozzle to the amount of ink flowing back from the orifice to the reservoir. Shows. That is,

[0067]

[Equation 8]

It is In the case where the total number of nozzles is 12 and the number of non-driving nozzles is 1, n >> k and α <1. Therefore, the crosstalk amount wc is

[0069]

[Equation 9]

It is

Therefore, in the embodiment of the present invention, in order to prevent crosstalk, the value of α, that is, Mf /
The relationship between Ma and crosstalk was obtained from the experimental results shown in Table 1, and Mf / Ma was set to 0.2 or less, and Sample 4 was configured to have Mf / Ma of 0.121.

Next, the maximum frequency fd is set for all n nozzles.
Even if it is driven by, the flow channel constants of the reservoir 8 and the filter 51 are set so that the supply does not become insufficient.

If the surface tension of the ink is γ, the peripheral length of the nozzle hole 4 is Ta, the area of the nozzle hole 4 is Sa, and the contact angle between the ink and the head material (for example, single crystal Si) is θ, then (θ≈
0) At this time, in order to prevent the problem that the supply of ink is insufficient and bubbles are taken in from the nozzle holes 4 and to perform stable driving,

[0074]

[Equation 10]

It is necessary that the following relationship be established. Here, Ph is a pressure applied by an ink supply system that supplies ink to the inkjet head from the outside. For example, when the ink tank holding the ink to be supplied to the head is an elastic body, a negative pressure is externally applied to the inkjet head due to the deformation of the ink tank, and the high pressure of the inkjet head and the ink tank. A predetermined pressure is applied from the outside by the arrangement relationship (water head value) in the depth direction. Therefore, the flow path resistance Rf of the reservoir 8 and the filter 51 is the flow path resistance Ra of the entire ink flow path.
It can be seen that the problem of insufficient ink supply due to the attachment of the filter 51 does not occur if it is small enough to be ignored as compared with. Further, from the experimental results in Table 1, Rf / Ra was set to 0.25 or less in this example, and Rf / Ra in sample 4 was set.
Ra was set to 0.173.

Table 1 below shows the results of an experimental investigation on crosstalk and insufficient supply of ink jet heads according to the present invention. The inkjet head used in the experiment has 12 nozzles.

[0077]

[Table 1]

In Sample 2 in Table 1, unstable ink ejection was observed due to insufficient supply during high frequency driving. In Sample 3, when 11 nozzles were driven and one nozzle was not driven, ejection of ink droplets was observed from the nozzle holes of the non-driven nozzles. Crosstalk and insufficient supply were not observed in Sample 1 and Sample 4, and the ink discharge amount w per one time was large in Sample 4, and the best result was obtained in the ink discharge characteristics. The number of openings of the filter of Sample 4 is 58, the width of the filter is 45 μm, and the length is 50 μm.

FIG. 8 is a plan view showing another embodiment of the present invention. Further, FIG. 9 is a cross-sectional view taken along the line DD in FIG. FIG. 8 shows an example in which a plurality of ink channels are configured in parallel, but some of the ink channels are omitted in the figure.

In FIG. 8 and FIG. 9, 53 is a void formed in the lower part of the ink supply section, which is a pressure buffer chamber. 54
Is an oxide transparent conductive film formed inside the pressure buffer chamber 53, and is made of the same ITO as the individual electrode 21. Reference numeral 55 is a buffer wall corresponding to the bottom wall of the ink supply unit and having the same thickness as the vibration plate 5. The pressure increase in the reservoir 8 portion that occurs when the ejection chamber 6 of the ink flow path is driven is absorbed and buffered by the buffer wall 55 and disappears, and the pressure mutual interference between the ink flow paths and the ink caused by the attachment of the filter 51. It prevents supply shortages. The main reason for providing the oxidized transparent conductive film 54 is to prevent the malfunction that the buffer wall 55 is stuck to the substrate 2 and does not function when the substrate 1 and the substrate 2 are anodically bonded.

When the ink capacity (compliance) of the reservoir portion 8 is sufficiently large, it is possible to buffer the pressure generated in the drive nozzle and spilled over the reservoir 8 only by the ink capacity. By positively providing the buffer wall 55 as in this embodiment, sufficient compliance can be obtained even if the volume of the reservoir 8 is small, and the pressure generated in the reservoir 8 during operation of the inkjet head is sufficiently buffered. can do. Further, the buffer wall 55 expands the range of selection of the flow channel constant of the filter 51. That is, by providing the buffer wall 55, even if the inertance of the filter 51 becomes a large value compared to the inertance of the entire ink flow path, the pressure is buffered, so that crosstalk does not occur.

In the above-mentioned embodiments, the electrostatic attraction force is used as the pressure generating means, but a piezoelectric element is adhered to the surface of the vibrating plate 5 on the opposite side of the discharge chamber 6 as the pressure generating means, and is appropriately applied to the piezoelectric element. The diaphragm may be deformed by applying an electric pulse. Further, a method of providing a heating resistor element as the pressure generating means in the ejection chamber 6 and obtaining a pressure for ejecting ink by thermal expansion of ink by the heating resistor element,
The same effects and advantages of the present invention can be obtained. As described above, the present invention is not limited to the one that uses the electrostatic attraction force as the pressure generating means, but by using the electrostatic attraction force as the pressure generating means, it is possible to reduce the gap amount. It is possible to obtain a large pressure, and it is possible to simplify the configuration of the head. If the electrostatic attraction force is used, the features of the present invention can be applied to the maximum extent.

FIG. 10 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 which sucks the ink through the cap 304 and the waste ink recovery 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.

In the ink jet recording apparatus of the present invention, the above-mentioned filter is built in the ink jet head 10. Therefore, in order to prevent foreign matter from entering the ink jet head 10, the filter is provided in the ink tank 301 and the ink supply tube 306. Since it is not necessary to provide the ink supply system, the ink supply system can be simply configured. Further, in the present embodiment, only the inkjet head 10 is replaced by the carriage 30.
However, the present invention is not limited to this, and the ink tank may be provided on the carriage, or a so-called disposable type (ink tank) in which the ink tank is integrated with the head. It goes without saying that the desired effect can be obtained even if the present invention is applied to a type in which the entire ink jet head is replaced when the ink becomes empty.

The method of manufacturing the ink jet head of the present invention will be described in detail below with reference to FIGS. 11 to 14.

FIG. 11 is a diagram for explaining the groove forming process of the substrate 1 in the method of manufacturing an ink jet head of the present invention. Each of the figures shows a cross section of a portion of the substrate 1 where the filter groove 52 is formed. Reference numeral 61 is a thickness 6 formed by thermal oxidation at 1100 ° C. on the surface of the substrate 1 which is single crystal Si.
It is a SiO2 thermal oxide film of 000Å. Reference numeral 62 is a resist which is a photosensitive resin applied on the surface of the substrate 1.

FIG. 11A shows that after the resist 61 is applied and dried on the surface of the substrate 1 after thermal oxidation, ultraviolet light is irradiated and exposed by using a positive mask in which a pattern is drawn only on the portion where the filter groove 52 is formed. Then, it is in a state of being developed, rinsed and dried. Referring to the width of the pattern, the width of the pattern for forming the filter groove 52 is narrower than the width of the pattern for forming the nozzle groove 11 and the narrow groove 13 shown in FIG.

Next, the oxide film was mixed with hydrofluoric acid and ammonium fluoride in a ratio of 1: 6 (volume ratio) to form an etching solution (BH
Etching according to F). Thereby, the filter groove 52
The oxide film in the pattern portion to be formed is removed.
Then, when the resist 61 is peeled off, the state shown in FIG. At this time, at the same time, the oxide film of the pattern portion, which is to form the groove to be the ink flow path and the ink supply portion, is also removed.

Further, the single crystal Si which is the substrate 1 is etched with an aqueous solution of potassium hydroxide (KOH) and ethanol. At this time, the (100) plane of the single crystal Si is (11
Since the etching is performed at 40 times the etching speed of the 1) plane, the (111) plane is exposed as a result. FIG. 11C shows a state after etching the single crystal silicon. At this time, the filter groove 52 is made of single crystal Si (11
1) Formed only on the surface. Since the filter groove 52 is composed of the (111) plane with a low etching rate, etching hardly progresses and the width and depth of the mask are stable with respect to the pattern width of the mask. Similarly, it is possible to form the groove shape with high accuracy in other ink flow paths and ink supply portions.

At the end of the groove formation, after cleaning with hot sulfuric acid, steam cleaning with isopropyl alcohol is performed, and the thermal oxide film on the surface is peeled off with BHF. FIG. 11D shows a state after the groove formation is completed after the thermal oxide film is peeled off. After that, a thermal oxide film serving as a protective film is formed again to complete the substrate 1.

FIG. 12 is an enlarged view of the filter 51 in FIG. 4 in the direction of arrow A. Further, FIG. 13 shows the reservoir groove 14
It is a perspective enlarged view after the etching of the filter groove 52 seen from the side. The filter 51 is etched to form a filter groove 52.
Is formed, and the substrate 1, the substrate 2, and the substrate 3 are joined, and then opened by cutting. Therefore, the shape of the opening is a triangle composed of two (111) planes of the Si single crystal and a (100) plane which is a bonding surface. In this way, it is easy to form a filter by using crystal planes having a relatively low filter formation rate, that is, an etching rate, and the same orthogonal crystal planes, that is, by configuring a filter in a triangular shape. It is possible to obtain a filter with high accuracy.

In the present embodiment, single crystal silicon is used for the substrate 1, but any material such as germanium or single crystal silicon oxide (quartz) that can be anisotropically etched may be used. Single-crystal silicon is a material that can be easily obtained as a semiconductor material in the industry, and quartz, germanium, and the like can obtain crystals of high purity and can be processed with higher precision.

In the following, a plurality of sets of ink flow path patterns are collectively formed on one wafer-shaped silicon substrate 1, and a large number of members to be the substrates 2 and 3 are also grouped together with the corresponding positions. A method for manufacturing an inkjet head will be described in which the inkjet head is manufactured, laminated and bonded, and then cut and separated into individual inkjet heads.

FIG. 14 is a pattern diagram showing a portion of a plurality of sets of ink flow path patterns anisotropically etched on a silicon substrate, which are cut and separated into individual ink jet heads in a later step. . The inkjet heads 10 and 10 ′ to be separated are arranged so that the nozzle 4 and the filter unit 51 face each other on the pattern. After joining the substrates 2 and 3, the cutting margin t of adjacent patterns
After removing a, the individual inkjet heads are separated. The pattern of the filter portion 51 overlaps with the cutting margin ta by tb, and the pattern of the nozzle 4 portion by tc, the cutting margin ta.
Overlaps with.

For example, by dicing, cutting / cutting
At the time of separation, a grindstone slightly narrower than the cutting allowance ta is used to separate the individual inkjet heads based on the filter section 51 side, and then the nozzle 4 section is polished and post-treatment such as water repellent treatment is performed. .

According to such a method, many ink jet heads can be produced at one time, so that it becomes possible to easily and inexpensively produce ink jet heads.
In this case, since the area of the opening of the filter 51 is the smallest with respect to the outside of the head, the filter groove is cut to manufacture the head, so that foreign matter may enter the head during handling during manufacturing. Can be prevented. As a result, manufacturing defects of the inkjet head can be reduced and more inkjet heads can be obtained. That is, the manufacturing yield can be improved.

The cutting process in the above cutting step may be grinding cutting by dicing, a cutting method of breaking after scribing (groove formation), scribing cutting by laser, or cutting process by water jet. Grinding cutting by dicing enables relatively accurate cutting. Particularly in dicing, the length of the filter 51 can be accurately ensured. Further, the method of breaking after scribing is the easiest cutting method capable of cutting in a short time and is suitable for mass production. Laser processing has the advantages that no chips are generated during cutting, the probability of clogging during manufacturing is low, and that cutting processing using a water jet is less susceptible to heat.

Whichever cutting method is used, there is no difference in the effect obtained by finally forming the filter 52 by cutting after joining the grooves formed by etching.

[0100]

As described above, according to the present invention, it is possible to obtain a highly reliable ink jet head which prevents clogging of the flow path due to inflow of foreign matter and is free from missing dots.

Further, it is possible to provide an ink jet head and an ink jet recording apparatus which can stably eject ink without pressure interference between ink flow paths and insufficient supply of ink and which can obtain good print quality.

Further, there is an effect that an ink jet head which can be easily manufactured, is inexpensive, and has high dimensional accuracy and high quality can be obtained.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an inkjet head according to an embodiment of the present invention.

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

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

FIG. 4 is a partially enlarged plan view of a substrate of an inkjet head according to an embodiment of the present invention.

FIG. 5 is a sectional side view showing an ink discharge operation of the inkjet head according to the embodiment of the present invention.

6 is an explanatory diagram showing a state of voltage applied to a diaphragm and individual electrodes of the inkjet head shown in FIG.

FIG. 7 is an explanatory diagram illustrating flow channel constants of respective ink flow channels in the inkjet head according to the embodiment of the present invention.

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

9 is a sectional view of the inkjet head of FIG.

FIG. 10 is a schematic diagram of a printer equipped with an inkjet head according to an embodiment of the present invention.

FIG. 11 is a cross-sectional view showing the process of manufacturing the substrate of the inkjet head according to the embodiment of the present invention.

FIG. 12 is an enlarged view of the opening portion of the filter of the inkjet head according to the embodiment of the present invention.

FIG. 13 is a partial perspective view of the substrate filter portion of the inkjet head according to the embodiment of the present invention.

FIG. 14 is anisotropically etched on a silicon substrate,
It is a pattern diagram which shows a plurality of sets of ink flow path patterns.

[Explanation of symbols]

1 ... Substrate 4 ... Nozzle hole 5: Vibration plate 6 ... Discharge chamber (pressure generator) 7 ... Orifice (ink supply path) 8 ... Reservoir (ink supply unit) 52 ... Filter

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadaaki Hakata 3-3-5 Yamato, Suwa City, Nagano Seiko Epson Corporation (72) Inventor Ikuhiro Miyashita 3-5 Yamato, Suwa City, Nagano Prefecture In Seiko Epson Corporation (56) Reference JP 5-193134 (JP, A) JP 2-89648 (JP, A) JP 5-50601 (JP, A) JP 6-47917 (JP, A) JP-A-2-277646 (JP, A) JP-A 62-8316 (JP, A) JP-A 60-147346 (JP, A) JP-A 57-116656 (JP, A) (JP 58) Fields investigated (Int.Cl. ⁷ , DB name) B41J 2/16 B41J 2/045 B41J 2/055 B41J 2/175

Claims (18)

(57) [Claims] 1. A plurality of nozzle holes, and each of the nozzle holes
Communication, each independent discharge chamber, and
An ink passage chamber and an orientation connecting the common ink chamber and the ejection chamber
Fice and a supply port for supplying ink to the common ink chamber
A filter including a plurality of grooves formed on the side, and the discharge
Pressure generating means for generating pressure in each of the chambers
Inkjet head, The pressure generating means is selectively driven to drive the pressure from the nozzle.
Inkjet recording device having a driving unit for discharging droplets
In the recording device, Each of the plurality of grooves forming the filter is the nozzle.
It has a smaller cross-sectional area than the cross-sectional area of the holes and
Nartance from the nozzle hole to the orifice
Less than one-fifth of inertance
Recording device. 2. The ink jet recording apparatus according to claim 1.
In, the flow path resistance of the filter from the nozzle
It should be 1/4 or less of the flow resistance to the orifice.
An ink jet recording apparatus according to claim 1, wherein
Place 3. The inkjet recording according to claim 1 or 2.
In the recording device, Part of the discharge chamber, part of the common ink chamber,
Constituting the grooves with each groove forming a part of the fiss
An anisotropic crystal substrate having a plurality of grooves formed on the first surface
When, Is bonded to the first surface of the anisotropic crystal substrate,
Both the discharge chamber, the common ink chamber, and the filter are
And a lid substrate formed respectively.
Cudget recording device. 4. The ink jet recording apparatus according to claim 1, wherein at least one wall surface of the common ink chamber is made flexible. 5. The ink jet head according to claim 3, wherein the anisotropic crystal material of the substrate is single crystal silicon. 6. The ink jet recording apparatus according to claim 1, wherein the pressure generating unit has a vibration plate provided on a part of a wall surface of the discharge chamber and a predetermined gap with respect to the vibration plate. And an electrostatic actuator having electrodes facing each other, wherein the driving unit is a driving unit that deforms the diaphragm by an electrostatic force obtained by applying a pulse voltage to the electrostatic actuator. Inkjet recording device. 7. The ink jet recording apparatus according to claim 1, wherein the pressure generating means includes a vibration plate provided on a part of a wall surface of the discharge chamber, and a piezoelectric element fixed to the vibration plate. The ink jet recording apparatus, wherein the driving means includes driving means for deforming the diaphragm by applying an electric pulse to the piezoelectric element. 8. The ink jet recording apparatus according to claim 1, wherein the pressure generating means is a heating element provided inside the discharge chamber, and the driving means applies an electric pulse to the heating element. By doing so, the ink jet recording apparatus is a driving unit that ejects ink droplets from the nozzle holes by vaporizing pressure generated in the ejection chamber. 9. A plurality of nozzle holes, and each of the nozzle holes
Communication, each independent discharge chamber, and
An ink passage chamber and an orientation connecting the common ink chamber and the ejection chamber
Fice and a supply port for supplying ink to the common ink chamber
Side filter and pressure in each of the discharge chamber
Inkjet comprising pressure generating means for generating
In the method of manufacturing the head, Part of the discharge chamber, part of the common ink chamber,
The first and second grooves of the anisotropic crystal substrate are formed with the grooves forming a part of the fiss.
A step of anisotropically etching the surface, Attaching the pressure generating means to the discharge chamber, Bonding the lid substrate to the first surface of the anisotropic crystal substrate
The edge of each groove is sealed with the discharge chamber,
Common ink chamber, the step of forming the orifice
Then The anisotropic etching step further comprises the steps of:
Nartance from the nozzle hole to the orifice
The fill should be less than one fifth of inertance
The plurality of grooves forming the first surface of the anisotropic crystal substrate.
A. Characterized by being formed by anisotropic etching on top
Method for manufacturing a jet jet head. 10. The etching according to claim 9, wherein an etching prevention film for preventing corrosion by an etching solution is uniformly formed on the first surface of the substrate made of the anisotropic material, and then etching is performed within the contours of the grooves. There is a step of forming a mask pattern by removing the prevention film, and the filter is constructed.
A method of manufacturing an inkjet head, wherein a width of a contour that forms a plurality of formed grooves is narrower than a width of a contour that forms another groove. 11. The anisotropic crystal substrate is a silicon substrate, and the mask pattern is (1) of the silicon substrate.
The ink-jet head manufacturing method according to claim 10, wherein the ink-jet head is formed on the (00) surface. 12. The method of manufacturing an ink jet head according to claim 10, wherein the etching prevention film is a thermal oxide film of silicon. 13. The filter according to claim 9, wherein a plurality of sets of grooves are anisotropically etched in one anisotropic crystal substrate, and another substrate is bonded, and then at least the filter is formed.
A method for manufacturing an inkjet head, characterized in that the inkjet head is cut and separated into individual inkjet heads by cutting a portion corresponding to a part of a plurality of grooves . 14. The method of manufacturing an ink jet head according to claim 13, wherein the method of cutting a portion corresponding to a part of the plurality of grooves forming the filter is grinding cutting by dicing. 15. The method of manufacturing an ink jet head according to claim 13, wherein the method of cutting a portion corresponding to a part of the plurality of grooves forming the filter is a method of breaking after scribing. 16. The method of manufacturing an ink jet head according to claim 13, wherein the method of cutting a part of the plurality of grooves forming the filter is scribe cutting with a laser. 17. The method of manufacturing an ink jet head according to claim 9, wherein the step of providing the pressure generating means in the discharge chamber includes a step of forming an electrode on an insulating substrate, and a bottom portion of a wall surface of the discharge chamber. For the diaphragm provided in
It is characterized by comprising a step of bonding the insulator substrate to a second surface of the anisotropic material substrate opposite to the first surface so that the electrodes face each other with a predetermined gap. Inkjet head manufacturing method. 18. The method of manufacturing an inkjet head according to claim 9, wherein the step of attaching the pressure generating means to the discharge chamber includes attaching a piezoelectric element to a vibration plate provided on a part of a wall surface of the discharge chamber. A method for manufacturing an inkjet head, which is a step of wearing.