JP3454258B2 - Ink jet recording device - 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.

[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 portion of the head is formed at the same time as the flow path by photoetching. This is to obtain an inkjet head having a built-in filter capable of stably ejecting ink.

[0004]

However, 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 section communicates with a plurality of flow paths to distribute and supply the ink to the ink flow paths, and at the same time alleviates the pressure due to the ink backflow from the ink supply paths when the ink is ejected from the nozzles. There is.

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) Further, even when the ink capacity of the ink supply portion 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 inertance of the filter is large. Similarly, there is a problem in that pressure interference occurs between the ink flow paths via the ink supply section, and ink is ejected from the nozzles of the flow path in which the pressure generation section of the flow path is not operating.

In any of these cases, the reliability of printing is deteriorated due to missing pixels of printed matter of a printer equipped with an ink jet head, stains on the printed matter, erroneous reading, etc., or the printed result is not clear. It causes troubles such as lowering the rank.

The present invention has been made in order to solve such problems, and an ink jet head and an ink jet which can stably eject ink without pressure interference between ink flow paths and obtain good print quality. It is an object to provide a recording device.

[0009]

An ink jet recording apparatus according to the present invention has an ink supply port, a common ink chamber, a plurality of grooves, one end of which communicates with the ink supply port and the other end of which communicates with the common ink chamber. An ink jet recording apparatus comprising: a filter; a plurality of nozzle holes that respectively communicate with a common ink chamber through independent discharge chambers; and a pressure generation unit that generates a pressure in each of the discharge chambers,
A pressure buffer chamber is provided under the common ink chamber,
The wall defining the boundary between the chamber and the common ink chamber is flexible .

According to the present invention, since at least one wall forming the common ink chamber is flexible, the pressure rise in the common ink chamber caused by the pressure generated in the ejection chamber of the driven nozzle (driving nozzle). Becomes smaller.

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.

[0012]

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 cross 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 stacked 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 with 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 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 this embodiment, the distance between the vibrating plate 5 and the electrodes 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 to 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 second lower 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, which is bonded to the upper surface of the first substrate 1, uses the same borosilicate glass as 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. Further, the reservoir 8 is provided with a convex portion 19 so as to have strength so that the concave portion is not crushed when the first substrate and the third substrate are bonded to each other. In this embodiment, the filter 51 simultaneously 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 subjected to anodic bonding by applying a temperature of 300 to 500 ° C. and a voltage of 500 to 1000 V, and the first substrate 1 and the third substrate 3 under the same conditions. 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 fills the reservoir 8, the discharge chamber 6, and the like. Then, as shown in FIG. 3, the ink in the ejection chamber 6 is ejected as ink droplets 104 from the nozzle holes 4 when the inkjet head 10 is driven, and is printed on the recording paper 105.

FIG. 4 is a partially detailed plan enlarged 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.
Each of the inner nozzle groove 11, the narrow groove 13 and the filter groove 52 is a V-shaped groove composed of a (111) surface with a low 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 54 recesses 14 communicate with 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) plane 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 the 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 that of 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 matters 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 defective printing such as dot omission does not easily 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. 5 (a) to 5 (c) 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. 5 (a) is a side sectional view of the ink jet head in the standby state, and FIG. 6 (a) 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, an electrostatic attraction force acts on the diaphragm 5 and the individual electrode 21. Then, the diaphragm 5 is attracted to the individual electrode 21. At this time, as shown in FIG.
The pressure in the ejection chamber 6 is reduced by the vibrating plate 5 sucked in, and ink is supplied from the reservoir 8 to the ejection chamber 6 in the arrow B direction. 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, when the timing at which the ink is sufficiently supplied is selected, the application of the voltage is stopped, and the electric charges stored in the diaphragm 5 and the individual electrode 21 are discharged.
As shown in (c), 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 and converged by the flow path resistance, and the standby state shown in FIG.
The next ink can be ejected.

In the driving method described above, the diaphragm is not deformed in the standby state, and the diaphragm is deformed at the time of driving, so that the pressure in the discharge chamber is once reduced, 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 represented by the following formula, where 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.

[0029]

[Equation 1] The inertance M is resistance to ink volume acceleration, and the larger the inertance M is, the greater resistance to force such as generated pressure and acceleration.

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

[0031]

[Equation 2] Indicated 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

[0033]

[Equation 3] Indicated 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 path constants of the ink flow paths that are formed are balanced and set while adjusting them 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, crosstalk (pressure interference between ink flow paths) in which ink droplets are ejected from non-driving nozzles by the driving method described with reference to FIGS. 5 and 6.
In addition, the flow channel constants such as the inertance of the reservoir 8 and the filter 51, the flow channel resistance, and the ink volume are set with respect to the flow channel constants of the ink flow channels so that insufficient supply of ink does not occur.

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. In addition, let the inertance of the entire flow path of the discharge section from the nozzles 4 to the orifices 7 configured in parallel of n be Ma and the flow path resistance be Ra, and the inertance of the flow path of the supply section configured by the reservoir 8 and the filter 51. And channel resistance are Mf,
Rf can be expressed as follows.

[0040]

[Equation 4] Here, Lf represents the length of the filter 51, Sf represents the cross-sectional area of the opening of the filter, and Tf represents the cross-sectional perimeter of the opening of the filter.

[0041]

[Equation 5] Here, 1 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 cross-sectional area of one flow path at any position x from the nozzle 4 to the orifice 7. , 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

[0043]

[Equation 6] Becomes t indicates time. At this time, the ejection amount of ink from one nozzle that is not driven (non-driving nozzle), that is, the amount wc of crosstalk resulting from mutual interference between ink flow paths.
Is the value obtained by dividing the pressure increase δPfk in the reservoir 8 by nMa twice, and

[0044]

[Equation 7] 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,

[0045]

[Equation 8] 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, so the crosstalk amount wc
Is

[0046]

[Equation 9] 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 when driven by, the flow channel constants of the reservoir 8 and the filter 51 are set so that the supply does not become insufficient.

When 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, (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,

[0050]

[Equation 10] It is necessary that the relationship be established. Where 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 applied to the inkjet head from the outside due to the deformation of the ink tank, and
A predetermined pressure is applied from the outside due to the positional relationship (water head value) between the inkjet head and the ink tank in the height direction. From this, it can be seen that if the flow path resistance Rf of the reservoir 8 and the filter 51 is negligibly smaller than the flow path resistance Ra of the entire ink flow path, the problem that the supply of ink is insufficient due to the attachment of the filter 51 does not occur. Further, from the experimental results in Table 1, Rf / Ra was set to 0.
25 or less, Rf / Ra of Sample 4 is 0.173
It is configured to be

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

[0052]

[Table 1]

In Sample 2 in Table 1, instability of ink ejection due to insufficient supply was observed 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 generated due to 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 driving nozzle and spilled over to 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 embodiments described above, the electrostatic attraction force was 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 the piezoelectric element is appropriately used. 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 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.

In the ink jet recording apparatus of the present invention, since the above-mentioned filter is built in the ink jet head 10, the filter is provided in the ink tank 301 and the ink supply tube 306 in order to prevent foreign matter from entering the ink jet head 10. 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 view 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.

In FIG. 11A, after the resist 61 is applied to the surface of the substrate 1 after thermal oxidation and dried, ultraviolet light is radiated and exposed using a positive mask in which a pattern is drawn only on a 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 this 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 channel 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 the substrates 2 and 3 are joined, the cut margin ta of adjacent patterns is removed to separate the individual inkjet heads.
The pattern of the filter portion 51 overlaps with the cutting margin ta by tb, and the pattern of the nozzle 4 portion overlaps with the cutting margin ta by tc.

For example, by dicing processing, 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 forming the filter 52 by etching after joining the grooves formed by etching.

[0075]

As described above, according to the present invention, it is possible to provide an ink jet head and an ink jet recording apparatus capable of stably ejecting ink without pressure interference between ink flow paths and obtaining good print quality. Is possible.

[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 3-3.5 Yamato, Suwa City, Nagano Prefecture In Seiko Epson Corporation (56) Reference JP 5-208503 (JP, A) JP 5-50601 (JP, A) JP 59-42964 (JP, A) JP 60-147346 (JP, A) JP-A-61-233545 (JP, A) JP-A-7-137262 (JP, A) Actual development 4-52050 (JP, U) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) B41J 2/045 B41J 2/05 B41J 2/055

Claims (7)

(57) [Claims] 1. An ink supply port, a common ink chamber, a filter having a plurality of grooves, one end of which communicates with the ink supply port and the other end of which communicates with the common ink chamber, and an independent ejection chamber, In an inkjet recording apparatus including a plurality of nozzle holes that communicate with a common ink chamber and a pressure generating unit that generates pressure in each of the ejection chambers, a pressure buffer chamber is provided below the common ink chamber,
The wall that defines the boundary between the buffer chamber and the common ink chamber is flexible.
An ink jet recording apparatus characterized by that. 2. The ink jet recording apparatus according to claim 1 , wherein an oxidized transparent conductive film is formed on the bottom surface of the pressure buffer chamber. 3. The claim 1 or 2, wherein the discharge chamber, said common ink chamber, an ink jet recording apparatus wherein the filter is characterized in that it is formed in the anisotropic crystal substrate. 4. The ink jet recording apparatus according to claim 3 , wherein the anisotropic crystal material of the substrate is single crystal silicon. 5. The one of claims 1 to 4, wherein the pressure generating means, wherein the discharge chamber diaphragm provided in a part of the wall of, with a predetermined gap with respect to the diaphragm An ink jet recording apparatus comprising an electrostatic actuator having opposing electrodes. 6. In any one of claims 1 to 4, wherein the pressure generating means comprises a diaphragm provided in a part of the wall of the discharge chamber, a piezoelectric element fixed to the vibrating plate An ink jet recording apparatus characterized by the above. 7. In any of claims 1 to 4, and wherein said pressure generating means, provided inside of the discharge chamber, and a heating element generating a vaporized pressure in the discharge chamber Inkjet recording device.