JPH10146976A - Ink jet printing head, and ink jet printing device on which the head is mounted - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a stable ink liquid drop discharging, and improve the reliability under a state wherein remaining air bubbles do not unfavorably affect the ink liquid discharging by a method wherein for an ink passage for which a protuberance is provided on a discharging port plate, a joint part is provided on adjacent energy generating elements, between an ink feeding port and the ink discharging energy generating elements. SOLUTION: On a substrate 4, an electric thermal converting element 1 which is a discharging energy generating element, and an ink feeding port are provided, and on both sides in the longitudinal direction of the ink feeding port, one line each of electric thermal converting elements 1 is arranged under a zig-zag state. Also, on the substrate 4, a coating resin layer 6 which becomes an ink passage wall to form an ink passage, is provided, and on the coating resin layer 6, a discharging port plate 5 equipped with a discharging port 2, is provided. Then, in order to suppress the growth of remaining air bubbles 9 to a degree wherein the remaining air bubbles 9 unfavorably affect the ink feeding characteristics, a protuberance 7 is provided directly above the ink feeding port on the internal surface of the discharging port plate, and in addition, a joint part which is co-owned by adjacent elements 1, is provided between the ink feeding port and the electric thermal converting element 1 for the ink passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet print head used in an ink jet recording system for ejecting small ink droplets and recording on a recording medium, and an ink jet printing system using the head.

[0002]

2. Description of the Related Art An ink jet recording system is one of so-called non-impact recording systems. As a feature of this recording method, the generation of noise during recording is small enough to be ignored, high-speed recording and recording on various recording media are possible, and no special processing is required for so-called plain paper. And high-definition images can be obtained at low cost. Due to these advantages, not only printers as peripheral devices of computers but also printing systems such as copying machines, facsimile machines, word processors and the like have been rapidly spreading in recent years.

[0003] Ink jet ink jetting methods widely used today include a method using an electrothermal transducer (heater) as an ejection energy generating element used to eject ink droplets, and a piezoelectric element (piezoelectric element). ), And the discharge of ink droplets can be controlled by an electrical signal. For example, the principle of an ink droplet ejection method using an electrothermal conversion element is that, by giving an electric signal to the electrothermal conversion element, the ink near the electrothermal conversion element is instantaneously boiled and is caused by a phase change of the ink at that time. Ink droplets are ejected at high speed by rapid growth of bubbles. On the other hand, the principle of a method of discharging ink droplets using a piezoelectric element is that an electric signal is applied to the piezoelectric element to displace the piezoelectric element, and the ink droplet is discharged by the pressure at the time of the displacement. Here, the former method does not require much space for the ejection energy generating element, has advantages such as a simple structure of the ink jet print head and easy integration of nozzles. On the other hand, the disadvantages inherent in this method are that the volume of flying ink droplets fluctuates due to heat storage in the inkjet print head, such as heat generated by the electrothermal transducer, the effect of cavitation due to defoaming on the electrothermal transducer, There is an effect on ink drop ejection characteristics and images due to bubbles remaining in the inkjet print head due to the dissolved air.

[0004] As a method of solving these drawbacks, Japanese Patent Application Laid-Open No. 54-161935, Japanese Patent Application Laid-Open No. 61-185455,
There are ink jet recording methods and ink jet print heads described in JP-A-61-249768 and JP-A-4-10941. That is, the ink jet recording method described in the above-mentioned publication is characterized in that bubbles generated by driving the electrothermal conversion element by a recording signal are communicated with the outside air. By using this recording method, it is possible to improve the volume stability of flying ink droplets, discharge small droplets at high speed, and improve the durability of the heater by eliminating cavitation generated when bubbles are bubbled out. Can be easily obtained. In the above-mentioned publication, as a configuration for communicating air bubbles with the outside air, a configuration in which the distance between the electrothermal conversion element and the discharge port is significantly shorter than in the related art is cited. An inkjet print head having this configuration has an ejection port plate provided with ejection ports corresponding to the electrothermal transducers, and an ink supply port opened in the substrate to supply ink from the back of the substrate. It is configured such that the ink droplet flies almost perpendicularly to the substrate on which the electrothermal conversion elements are arranged. (See Figures 1 and 8). Here, it is desirable that the (shortest) distance between the electrothermal conversion element and the discharge port be 30 μm or less.

[0005]

The structure described in the above-mentioned publication is one of the drawbacks mentioned above, in that the ink droplet discharge characteristics and image due to bubbles remaining in the ink jet print head due to air dissolved in the ink are reduced. The impact is still not fully resolved,
It has been found that this problem is more likely to appear remarkably because the height of the flow path is low. In the following, the effect of air dissolved in the ink on the ink droplet ejection characteristics and image due to bubbles remaining in the ink jet print head will be described in detail. In the ink in the ink jet print head, air is usually dissolved in a saturated state. When the electrothermal transducer is driven in this state, the air dissolved in the ink is reduced by one due to the repetition of bubbling due to the phase change of the ink and rapid adiabatic shrinkage of the bubbles.
It may suddenly appear in the ink as undissolved bubbles having a diameter of about μm or less. Further, it is known that such bubbles are re-dissolved in the ink in a time determined by the diameter of the bubble, the surface tension of the ink, the saturated vapor pressure of the air, and the like. For example, when the bubble diameter is 1 μm or less, the time required for dissolution is on the order of 1 μs or less. However, when a plurality of electrothermal transducers are continuously driven at a high frequency, a plurality of such bubbles appear in the ink and grow together before being re-dissolved. It is known that as the bubble diameter increases, the time required for re-dissolution increases significantly, but as a result, a plurality of residual bubbles of several tens μm to several hundreds μm are stored in the inkjet print head. In such a case, these residual bubbles hardly redissolve in the ink, and adversely affect the ejection characteristics of the ink droplets. That is,
If the residual air bubbles block the ink flow path, the nozzles will not be filled with sufficient ink, causing ejection failure. In addition, huge residual air bubbles (approximately several hundred μm) are generated inside the ink jet print head, and if the residual air bubbles happen to communicate with the outside air, the outside air enters into the nozzle and the meniscus is destroyed. Therefore, the negative pressure for sucking up the ink in the ink tank may cause the ink inside the ink jet print head to be sucked up by the ink tank, causing all the nozzles to become non-ejection. The most effective solution to avoid the adverse effects of such residual air bubbles is to discharge the residual air bubbles together with the ink by suction, pressurization, etc. from the ejection port before the residual air bubbles grow so badly that There is a method of performing a so-called suction (pressure) recovery process. However, in this case, the amount of ink consumption increases remarkably, and if this is performed during printing, the throughput naturally decreases. As another method, there is a method in which air dissolved in the ink is discharged from the ink by some method (degassing), and such ink is used for an ink jet print head. The time when this solution works best is
Since it takes about several tens of minutes after deaeration of the ink and the device for deaeration of the ink is relatively large, this method can be used only for a large-scale printing system or the like.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and alleviates the adverse effect of bubbles remaining in an ink jet print head on ink liquid discharge, thereby stably discharging ink droplets. And a highly reliable ink jet print head.

It is another object of the present invention to provide an ink jet printing device which has excellent throughput by controlling the residual bubbles and reduces the number of times of the recovery processing, and consumes a small amount of ink.

In order to achieve the above object, a plurality of ejection energy generating elements for generating energy used for ejecting ink droplets, an ink ejection port for ejecting the ink droplets, and the plurality of ejection energy generating elements are provided. A substrate having an ink supply port consisting of a through-hole that is arranged in a row and extends along the arrangement direction of the ejection energy generating elements, and an ejection port plate including the ink ejection port,
An ink jet print head, wherein the substrate and the discharge port plate are joined and an ink flow path communicating the ink discharge port and the ink supply port is formed between the substrate and the discharge port plate. The plate has a plurality of protrusions at positions corresponding to the ink supply ports, and the ink flow path has a common portion shared by adjacent discharge energy generation elements between the ink supply ports of the substrate and the ink discharge energy generation elements. It is characterized by having.

According to the ink jet print head having the configuration according to the present invention as described above, it is possible to mitigate the adverse effect of the bubbles remaining inside the ink jet print head on ink droplet ejection. In addition, the inkjet printing device equipped with the inkjet print head having the configuration according to the present invention hardly affects the ejection characteristics even when the bubbles grow to a size of several hundred μm. The means for discharging bubbles together with the ink to the outside is minimized, so that the throughput can be improved and the ink consumption can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the operation of the present configuration will be described in detail with reference to the drawings and the like in comparison with a conventional example.

FIG. 4 is a typical ink jet print head having a structure according to the present invention, FIG. 8 is an ink jet print head having a conventional structure, and FIG. 9 is a diagram showing the structure of the present invention. An ink jet print head having a configuration similar to the above configuration, specifically, a configuration in which an isolation wall for forming an individual ink flow path for each electrothermal conversion element reaches the ink supply port. . These print heads have an ink droplet ejection means characterized by the ink jet recording method described in JP-A-4-10940 and JP-A-4-10941, that is, have a feature of communicating foaming during ejection with outside air. . Each drawing shows an enlarged view as viewed from the front of the substrate on which the electrothermal conversion elements are arranged, and a vertical cross-sectional view in the AA ′ and BB ′ directions.

First, how the residual air bubbles remaining without being dissolved in the ink jet print head affect the ejection will be described. It has been found by observation and the like that in a conventional ink jet print head, residual bubbles attached to the inner surface of the ejection port plate near the supply port at some point grow as shown in FIG. The residual air bubbles 9 are locally generated by the ink flow in the ink jet print head due to the discharge of the ink droplets, specifically, the ink flow toward the discharge port 2 generated to refill the ink flow path with the ink. It has a shape that is easily drawn into the road. Actually, when a residual bubble 9 of about 150 μm is present at a position as shown in FIG. 8, the residual bubble 9 is drawn into the ink flow path, whereby the ink in the ink flow path is divided by the bubble, and the ink flow path Insufficient ink supply to the printer. According to observations by the present inventors, if ink droplet ejection is further continued as it is, the residual bubbles 9 gradually move toward the ejection port 2 side, and the ink jet printing is performed at the moment when the residual bubbles 9 communicate with the outside air. It has been found that the ink in the head becomes empty.

This phenomenon will be described with reference to a simple model shown in FIG. In FIG. 3, the thin tube is now filled with ink and one end (A) is kept at atmospheric pressure and the other end (B) is kept at atmospheric pressure-P (kPa). It is assumed that ink can freely enter and exit the tube. Here, P is a negative pressure at which the ink tank of the ink jet print head is sucking up the ink. In A, the forces are balanced by the capillary force of the ink, and a meniscus is formed. Here, assuming that bubbles 9 having a diameter r (μm) exist in the ink and the surface tension of the ink is γ (dyn / cm), the internal pressure of the bubbles 9 is atmospheric pressure−P + 2γ / r (Equation 1) Can be represented by In this state, the bubble 9 is brought closer to the side A, and at a certain time, the bubble 9 is communicated with the atmosphere. Here, when the atmospheric pressure−P + 2γ / r> atmospheric pressure (Equation 2), that is, when P <2γ / r (Equation 3) is satisfied (see (i)), the internal pressure in the bubble 9 is higher than the atmospheric pressure. Due to the high air bubbles 9 are discharged to the atmosphere just like a balloon collapses, forming a meniscus as shown by the dotted line. Conversely, if the atmospheric pressure−P + 2γ / r <atmospheric pressure (Equation 4), that is, if P> 2γ / r (Equation 5) holds (see (ii)), the internal pressure in the bubble 9 becomes lower than the atmospheric pressure. Due to the low temperature, there is a rapid inflow of air from the atmosphere into the bubbles 9 and the inside of the tube is instantly filled with air as indicated by the dotted line.

As can be seen from the above description, when there is a residual bubble having a size such that P> 2γ / r, ie, r> 2γ / P, near the ink flow path, the residual bubble communicates with the outside air. The phenomenon that the ink in the ink jet print head becomes empty at the moment of the occurrence may occur. In the experiments of the present inventors, while using γ = 47.8 dyn / cm ink, the negative pressure P in the tank was checked at 1 kPa,
The calculated critical diameter of the residual bubbles is 95.6μm, and the predictions and experimental results are almost the same.

Therefore, the present inventors have found a configuration in which a projection is provided immediately above the ink supply port on the inner surface of the ejection port plate in order to suppress the residual bubbles from growing so as to adversely affect the ink supply characteristics. With the provision of the projections, it is observed that the diameter of the residual bubbles that adhere to and grow on the inner surface of the discharge port plate does not grow beyond the gap between the projections. For this reason, even if the residual bubbles communicate with the atmosphere, the worst case in which the ink in the ink jet print head becomes empty can be prevented if the gap between the protrusions is shorter than 2γ / P. However, the smaller the gap between the projections, the better. Conversely, if it is too narrow, not only the effect of the present invention will not be achieved, but also residual air bubbles adhering to the ejection port plate will enter between the projections and cannot be removed even by a recovery process such as ink suction. According to the empirical viewpoint of the present inventors, it is desirable that the projection gap is at least 10 μm or more. Usually, in an ink jet print head that ejects an ink whose main component is water, the ink is γ = 40 to 50 dyn / cm
It is desirable to be. Further, it is said that the tank is preferably used at a negative pressure P of 0.5 to 2 kPa. From these, it can be seen that a = 2γ / P is usually in the range of 40 μm ≦ a ≦ 200 μm. Therefore, the gap between protrusions is 10μ.
m or more and 40 μm or less, inks having various kinds of γ which are generally suitable for an ink jet print head, various kinds of inks
Also works well in tanks with P.

Investigations have been further conducted. The ink flow path has a common portion shared by the adjacent discharge energy generating elements between the ink supply port of the substrate and the ink discharge energy generating element. It was found that air bubbles entering the road can be significantly reduced. That is, as shown in FIG. 9, if the configuration is such that the individual bubbles are separated from the vicinity of the ink supply port where the residual air bubbles are likely to accumulate to the respective electrothermal conversion elements, the ink supply in the ink flow path The mouth end is covered with the residual air bubbles, and the residual air bubbles are taken into the ink flow path. In the present invention, the ink flow path has a common portion shared by the adjacent discharge energy generating elements between the ink supply port of the substrate and the ink discharge energy generating element, so that the individual ink for each electrothermal conversion element is provided. Since the ink supply to the flow path has at least two or more paths on the substrate, even if some of the ink supply paths are covered with residual bubbles, ink is supplied from the remaining ink supply paths and It is possible to remarkably reduce the possibility that residual air bubbles may enter the air.

FIG. 4 shows a configuration according to the present invention, that is, a plurality of projections at positions corresponding to the ink supply ports of the discharge port plate, and an ink flow path between the ink supply port of the substrate and the ink discharge energy generating element. FIG. 3 is a schematic diagram showing a typical inkjet print head having a configuration having a common part shared by adjacent ejection energy generating elements.

It has been confirmed that a typical ink-jet printhead having the structure according to the present invention has two bubble growth points. One is the residual air bubbles that adhere to and grow on the inner surface of the discharge port plate, and the other is the residual air bubbles that adhere to and grow at the tip of the projection. As described above, it is possible to control the growth of the residual air bubbles that adhere to and grow on the inner surface of the discharge port plate by using the projections and control the ink to be supplied stably. On the other hand, it is known from observations and the like that the remaining air bubbles that adhere to and grow at the tip of the projection are grown as shown in FIG. These residual bubbles are slightly deformed locally due to the flow of ink toward the discharge port, which is caused by refilling the ink flow path after the ink droplet is discharged. I couldn't.
This is because the protrusion provided on the inner surface of the ejection port plate is configured to just prevent the entry of the residual air bubbles into the ink flow path, and the ink flow path is connected to the ink ejection energy generating element from the ink supply port of the substrate. This is because there is a common portion shared by the adjacent ejection energy generating elements between them, so that it is possible to receive the ink supply from a wide range indicated by the arrow in the figure, and thus it is possible to prevent the shortage of the ink supply from occurring. That is, in the configuration according to the present invention, the ink in the ink flow path is not divided by the residual air bubbles being drawn into the ink flow path, and the ink supply to the ink flow path is insufficient and the communication with the atmosphere is prevented. This makes it very unlikely that the ink in the ink jet print head becomes empty, thereby providing a stable ink droplet ejection and highly reliable ink jet print head.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic view of an ink-jet printhead showing a basic embodiment of the present invention, which is cut on an appropriate surface for explanation. In addition, in this figure and below, electric wiring etc. for driving the electrothermal transducer is not shown. FIG. 2 is a cross-sectional view of the inkjet printed circuit board of FIG. 1 taken along the line AA 'in each step. FIG. 2 briefly shows a method of manufacturing the ink jet print head of the present invention.

In FIG. 1, reference numeral 4 denotes an ejection energy generating element 1
And an ink supply port 3.Electrothermal conversion elements 1, which are ejection energy generating elements, are arranged in a staggered pattern on both sides in the longitudinal direction of the ink supply port 3, which is a long groove-shaped through-hole. Elements are arranged at a pitch of 300 dpi on one side row. A coating resin layer 6 serving as an ink flow path wall for forming an ink flow path is provided on the substrate 4, and a discharge port plate 5 further including the discharge port 2 is provided on the coating resin layer 6. ing. Here, in FIG. 1, the coating resin layer 6 and the discharge port plate 5 are shown as separate members, but the coating resin layer 6 is formed on the substrate 4 by a method such as spin coating to form the coating resin layer 6. And the discharge port plate 5 can be formed simultaneously as the same member. Reference numeral 7 denotes a projection provided directly above the ink supply port 3 on the inner surface of the ejection port plate. In the present invention, by providing the projections 7 as described above, the adverse effect of the bubbles remaining inside the ink jet print head on the ejection of the ink liquid can be reduced. Further, the ink jet print head of the present invention has a configuration in which the ink flow path has a common portion shared by the adjacent discharge energy generating elements between the ink supply port of the substrate and the ink discharge energy generating elements. Specifically, the configuration is such that an isolation wall for forming an individual ink flow path for each electrothermal conversion element does not reach the ink supply port. Here, the shape of the protrusion is preferably formed by a rib along the ink flow direction from the ink supply port 3 toward the discharge port 2 from the viewpoint of minimizing the flow resistance of the ink flow path. As long as the range satisfies the range, the shape may be, for example, composed of a plurality of columns. Also,
From the viewpoint of ink supply, it is desirable that the projection is separated from the substrate, and the separation distance of the projection at this time is the shortest distance from the end of the projection to the substrate as in the above-described gap of 10 to 40 μm.
It is desirable to be within the range of m. In the case where the protrusion 7 is formed of a rib extending in the above-described ink flow direction, the strength of the ejection port plate can be improved by bringing the rib into contact with the substrate. Further, at this time, the flow resistance of the ink in the ink flow path can be reduced by making the end of the rib tapered. Further, in FIG. 1, the height of the protrusion 7 and the height of the ink flow path wall 6 are the same, but the height of the protrusion 7 does not necessarily need to be the same as the height of the ink flow path wall. Also, the shortest distance from the end of the projection to the substrate is the same as above.
What is necessary is just to form so that it may fall in the range of 10-40 micrometers.

In addition, the shortest distance from the end to the substrate of the above-mentioned isolation wall is 10 to 40 μm, like the projection.
It is desirable to be within the range.

An example of a method for manufacturing an ink jet print head according to the present invention will be described below.

First, a substrate 4 on which a plurality of electrothermal transducers 1 and necessary wiring (not shown) for driving them are provided on a Si chip by patterning or the like is prepared (see FIG. 1).
2-A) A dissolvable resin layer 12 is formed on the substrate 4 (FIG. 2-B). In the resin layer 12, an ink flow path pattern is left using a photoresist method or the like, and a portion corresponding to an appropriate protrusion above a position where a nozzle wall and a supply port, which is a feature of the present invention, is formed is removed. (Fig. 2-
C). Further, a coating resin layer 6 is formed on the dissolvable resin layer 12 'on which the ink flow path pattern is formed as described above.
2-D) The portion corresponding to the discharge port 2 in the coating resin layer 6 is removed (FIG. 2-E). Next, the supply port 3 is formed by, for example, chemically etching the substrate 4 from the back.
F). More specifically, a strong alkaline solution (KOH, NaOH, TM
The supply port 3 is formed by anisotropic etching using AH). Finally, the soluble resin layer 12 'is eluted (Fig. 2-
G) As a result, it is possible to obtain an ink jet print head chip having the ejection port 2, the supply port 3, the flow path communicating with them, and the projection 7 formed on the side of the ejection port plate immediately above the supply port. The ink jet print head of the present invention can be obtained by electrically connecting the chip to a wiring board for driving the electrothermal transducer.

The above-described method of manufacturing an ink jet print head is disclosed in, for example, Japanese Patent Application Laid-Open No.
It is preferable for manufacturing an ink jet print head using the ink jet recording method described in JP-A-0941 as an ink droplet discharging means. Each of these publications is an ink droplet ejection method characterized in that bubbles on an electrothermal transducer generated by a recording signal are communicated with the outside air.
The following is an inkjet printhead that enables ejection. In the inkjet print head, since the bubbles communicate with the outside air, the volume of the ejected ink droplet depends almost on the volume of the ink between the electrothermal transducer and the ejection port. In other words, it has a feature that it is almost determined by the structure of the nozzle portion of the ink jet print head. Therefore, the inkjet print head can output a high-quality image without unevenness. The structure of the present invention is applied to the above-described ink jet print head, that is, an ink jet print head in which the (shortest) distance between the electrothermal transducer and the discharge port is 30 μm or less in order to communicate air bubbles with the outside air. Although the maximum effect is exhibited, any ink jet print head which makes ink droplets fly perpendicular to the surface of the substrate on which the electrothermal conversion elements are arranged can be effectively used.

Further, in the ink jet print head of the present invention, by driving each electrothermal conversion element by distributed driving so that adjacent electrothermal conversion elements are not simultaneously driven, the adverse effects due to residual bubbles can be more effectively prevented. It can be relaxed.

The structure of the ink jet print head of the present invention will be specifically described below. In each of the embodiments, the ink jet print head prepared according to the procedure shown in FIGS. Nozzle spacing is 300dpi pitch on one side row, discharge port plate thickness 8μm,
The height of the protrusion and the nozzle wall, which is a feature of the present invention, is 12 μm.
It is. The ink used for evaluation was a Canon dye-based black ink (surface tension 47.8 dyn / cm, viscosity 1.8 cp, pH
9.8) was used.

Embodiment 1 FIG. 4 shows an enlarged view of the ink jet print head of this embodiment as viewed from the front of a substrate on which electrothermal transducers are arranged, and a cross-sectional view taken along the lines AA 'and BB'.

The dimensions of the projections of the present embodiment projected onto the discharge port plate surface are 20 × 150 μm, and the distance between the projections is 600 d.
They are arranged at a pi pitch (42.3 μm). That is, the gap between adjacent protrusions is at least 22.3 μm.

The ink jet print head of this embodiment was driven at an ejection frequency of 10 kHz, black solid was continuously recorded, the duration was measured, and comparative evaluation was performed. As a result, in the present embodiment, solid black could be printed for almost four times as long as that of the conventional inkjet print head.

(Embodiment 2) FIG. 5 is an enlarged view of the ink jet print head of this embodiment as viewed from the front of a substrate on which electrothermal transducers are arranged, and FIG. 5 is a cross-sectional view along AA 'and BB'.

The dimensions of the projections of the present embodiment when projected onto the discharge port plate surface are 40 × 40 μm, and the interval between the projections is 80 μm.
(The gap is 40 μm).

The ink jet print head of this embodiment was driven at an ejection frequency of 10 kHz, black solid was continuously recorded, the duration was measured, and comparative evaluation was performed. As a result, in the present embodiment, solid black can be printed for almost four times as long as that of the conventional ink jet print head, and the present invention works well even with such a configuration.

It is clear that an ink jet print head having such a thin film-shaped discharge port plate has low reliability in terms of strength of the discharge port plate itself. In particular, when the ejection port plate is made of resin, the ejection port plate may be swelled and deformed by ink or the like.
This can adversely affect the ink droplet ejection characteristics of the inkjet print head. For this reason, the following Examples 3 and 4 have also proposed the protrusion according to the present invention as a measure for ensuring the strength. By bringing the protrusion into contact with both the substrate and the discharge port plate, it is possible to secure a higher strength than when there is no protrusion on the discharge port plate, and it is possible to further increase the reliability.

(Embodiment 3) FIG. 6 is an enlarged view of the ink jet print head of this embodiment as viewed from the front of a substrate on which electrothermal transducers are arranged, and FIG. 6 is a cross-sectional view along AA 'and BB'.

The feature of the projection of this embodiment is that the projection comes into contact with both the substrate and the ejection port plate to increase the strength of the ejection port plate, secure ink supply to the nozzles, and suppress the flow resistance. Is characterized in that the width in a plane parallel to the discharge port plate is continuously narrowed toward the electrothermal transducer. The width of the projections of the present embodiment projected onto the discharge port plate surface is 20 μm at a large position and 12 μm at a small position. 600dpi spacing between projections
(42.3μm). That is, the gap between the projections is at least 22.3 μm.

The ink jet print head of the present embodiment was also driven at an ejection frequency of 10 kHz, black solids were continuously recorded, the duration was measured, and comparative evaluation was performed. As a result, in the present embodiment, solid black can be printed for almost four times as long as that of the conventional ink jet print head, and the present invention works well even with such a configuration.

(Embodiment 4) FIG. 7 shows an enlarged view of the ink jet print head of this embodiment as viewed from the front of a substrate on which electrothermal transducers are arranged, and a cross-sectional view taken along the lines AA 'and BB'.

The feature of the protrusion of the present embodiment is that the same protrusion is in contact with both the substrate and the discharge port plate across the supply port, thereby improving the strength of the discharge port plate as compared with the third embodiment. This is also characterized by the fact that the width of the protrusion in the plane parallel to the ejection port plate is continuously narrowed toward the electrothermal transducer in order to secure the ink supply to the nozzles and suppress the flow resistance. I have. The width of the projections of the present embodiment projected onto the discharge port plate surface is 20 μm at a large position and 12 μm at a small position. 600dpi spacing between projections
(42.3μm). That is, the gap between the projections is at least 22.3 μm.

The ink jet print head of this embodiment was also driven at an ejection frequency of 10 kHz, and the solid black was continuously recorded, the duration was measured, and a comparative evaluation was performed. As a result, in the present embodiment, solid black can be printed for almost three times as long as that of the conventional ink jet print head, and the present invention works well in such a configuration.

[0041]

As described above, according to the present invention,
It is possible to provide a highly reliable ink jet print head in which stable discharge of ink droplets and high reliability can be provided by alleviating the adverse effect of bubbles remaining inside the ink jet print head on ink droplet discharge. Further, by controlling the residual bubbles, the recovery process does not need to be performed frequently, so that the effects of improving the throughput and reducing the ink consumption can be achieved. Further, as an effect of the present invention, in an ink jet print head having a thin film-shaped discharge port plate, the reliability of the discharge port plate itself in terms of strength can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of an ink jet print head showing a basic mode of the present invention.

FIG. 2 is an explanatory diagram for explaining a method for manufacturing an ink jet print head of the present invention.

FIG. 3 is an explanatory diagram for explaining a state of a residual bubble in an inkjet print head.

FIG. 4 is a schematic diagram illustrating an inkjet print head according to the first embodiment.

FIG. 5 is a schematic diagram illustrating an inkjet print head according to a second embodiment.

FIG. 6 is a schematic diagram illustrating an inkjet print head according to a third embodiment.

FIG. 7 is a schematic diagram illustrating an inkjet print head according to a fourth embodiment.

FIG. 8 is a schematic view showing a conventional ink jet print head.

FIG. 9 is a schematic view of an ink jet print head in which a nozzle wall reaches directly above a supply port.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge energy generation element 2 Discharge port 3 Supply port 4 Substrate 5 Discharge port plate 6 Coating resin layer (nozzle wall) 7 Projection 8 Ink 9 Residual bubble 10 Direction of ink flow toward nozzle 11 Residual bubble generated by ink flow Deformation 12 Soluble resin layer 13 Ink flow path pattern

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Michiya Mizutani 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Yasuyuki Tamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside (72) Inventor Ikumo Watanabe 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tamaki Sato 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masayoshi Tachihara 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (14)

[Claims] A plurality of ejection energy generating elements for generating energy used for ejecting ink droplets;
A substrate having an ink discharge port for discharging the ink droplets, an ink supply port having a plurality of discharge energy generating elements arranged in a row, and a through-hole extending along an arrangement direction of the discharge energy generating elements; A discharge port plate having the ink discharge ports, and an ink flow path communicating the ink discharge ports and the ink supply ports between the substrate and the discharge port plate, wherein the substrate and the discharge port plate are joined. In the formed inkjet print head, the discharge port plate has a plurality of protrusions at positions corresponding to the ink supply ports, and the ink flow path is provided between the ink supply ports of the substrate and the ink discharge energy generating elements. An ink-jet printhead having a common portion shared by adjacent ejection energy generating elements. 2. The ink jet print head according to claim 1, wherein the plurality of ejection energy generating elements are arranged on both sides in the extending direction of the through-hole. 3. The ink suctioning force when the ink tank supplies ink to the ink supply port is represented by P (kP).
3. The ink jet print head according to claim 1, wherein a), when the surface tension of the ink is γ (dyn / cm), a gap between the adjacent protrusions of the plurality of protrusions is 10 μm or more and 2γ / P μm or less. 4. A gap between adjacent ones of the plurality of protrusions is not less than 10 μm and not more than 40 μm.
Or the inkjet printhead of 2. 5. The ink-jet print according to claim 1, wherein the plurality of projections are a plurality of ribs provided in a direction along an ink flow direction from the ink supply port toward the ejection port. head. 6. The ink jet print head according to claim 5, wherein an end of the rib is separated from a substrate. 7. The ink-jet printhead according to claim 6, wherein a shortest distance from an end of the rib separated from the substrate to the substrate is from 10 μm to 40 μm. 8. The ink-jet printhead according to claim 1, wherein a part of the projection is in contact with the substrate. 9. The ink jet print head according to claim 5, wherein an end of the rib has a tapered shape. 10. The ink jet print head according to claim 1, wherein the ejection energy generating element is an electrothermal conversion element. 11. The ink-jet printhead according to claim 10, wherein the electrothermal transducer is driven in a distributed manner. 12. The ink-jet printhead further has a separating wall for forming an individual ink flow path for each of the electrothermal transducers, and a shortest distance from a tip of the separating wall to the substrate is 10 to 40 μm. The inkjet printhead according to any one of claims 1 to 11, wherein: 13. The ink jet print head according to claim 10, wherein a distance from the ink ejection port of the ink jet print head to the corresponding electrothermal transducer is 30 μm or less. 14. An ink jet printing device comprising the ink jet print head according to claim 1 and a recovery unit for performing a recovery process of the ink jet print head.