JPH11188876A - Ink jet recording head, and ink jet recording apparatus equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the stability of emission even if ink is emitted by high frequency driving by making the peripheral edge region of an emitting orifice containing the opening edge part thereof water-repellent and the outside of the peripheral edge region of the emitting orifice hydrophobic and setting the relation between the opening longest width of the emitting orifice and the width of the peripheral edge region thereof so as to satisfy a specific formula. SOLUTION: An ink jet recording head has a structure formed by bonding a wall member 3 for forming at least liquid chambers 9, liquid passages 5 and an emitting orifice forming surface 1 to a substrate 4 having emitting energy generating elements 2 and the peripheral edge region 7 containing the opening edge part of each emitting orifice 1 of the emitting orifice forming surface 6 is set to a hydrophilic region and the outside thereof is set to a water-repellent region. The width (W) of this peripheral edge region 7 is 1/2 or less, pref., 1/4 or less the opening width (L) of the emitting orifice 1. When the caliber of the emitting orifice is different in respective direction of an opening surface, for example, the emitting orifice is rectangular, the longest width of the opening of the emitting orifice 1 is set to (LM) so as to satisfy the formula W<(LM/2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet recording head having a discharge port surface on which an ink discharge port is opened and having a structure suitable for high-frequency driving, and an ink jet recording apparatus equipped with the head.

[0002]

2. Description of the Related Art An ink jet recording system is one of so-called non-impact recording systems. The features of this recording method are that noise is hardly generated at the time of recording, high-speed recording is possible, recording and recording can be performed on various recording media, colorization is easy, and high recording is possible. It can be mentioned that a fine image can be obtained at low cost. Due to these various attractive features, which are notable, the inkjet recording method has been adopted in almost all fields of recording, such as copying machines, printers, facsimiles, and word processors, and has been widely and widely used today. .

As a typical method of the ink jet recording method, there is a method using an electrothermal transducer for discharging ink droplets. This is achieved by giving an electric pulse as a recording signal to the electrothermal transducer, causing the ink liquid near the electrothermal transducer to instantaneously boil, and by the rapid growth of bubbles generated by the phase change of the ink liquid at that time. This is a method in which ink droplets are ejected at a high speed from an ejection port. Advantages of this method include practical advantages such as simple structure, good electric responsiveness, easy microfabrication, and easy integration of nozzles for ejecting ink droplets. The feature is that there are many.

By the way, in the current ink jet recording system, when ink droplets are ejected, minute ink particles are necessarily generated along with main ink droplets. This is called an ink mist. The ink mist adheres to the periphery of the ejection port on the ejection port forming surface, and when the ink mist is combined with each other, a liquid pool of ink is formed. In a state in which the ink mist is formed by the ink mist at a part of the opening edge of the ejection port, when the ink droplet ejected from the ejection port and the ink pool at the ejection opening edge come into contact with each other, they are mutually connected. In some cases, the trajectory of the ink droplet ejected from the ejection port is deviated from a normal trajectory due to being attracted by surface tension. In addition, when the ink droplets accumulated around the discharge port are left undisturbed, the solvent evaporates therefrom and the viscosity of the ink droplets increases. When the thickened ink droplet flows back into the ejection port, the ejection port may be blocked by the thickened ink droplet, or the effective diameter of the ejection port may be narrowed, and ejection failure or ejection failure may occur. .

Various methods have been attempted to solve the problems related to the behavior of the ink near the discharge port, stabilize the discharge trajectory of the ink droplets at all times, and obtain a high-definition recorded image. .

As such a method, for example, a method of performing a water-repellent treatment on at least a region including an opening edge of a discharge port on an ink discharge port forming surface is known. FIG. 11 shows an example. This figure is a perspective view of a part of the ink jet recording head from the ejection port forming surface side, together with a partial cross section along a liquid path. In the figure, 1 is a discharge port, 2 is an electrothermal conversion element, 4 is a substrate on which the electrothermal conversion element is arranged, 5 is a liquid path, and 6 is a water-repellent film that forms a water-repellent surface on the entire surface. The discharge port forming surface 8 is a grooved top plate formed integrally with the liquid chamber, the liquid path, and the discharge port forming surface. The ink is ejected from the ejection port 1 along the axial extension of the liquid path 5 (the direction of the arrow).

As described above, by forming a water-repellent film on the surface on which the discharge port is formed by, for example, applying a water-repellent film, the ink mist attached to the surface on which the discharge port is formed grows together. It is possible to prevent the formation of ink droplets on the ejection port forming surface. This is because the contact angle of the ink becomes large on the water-repellent surface, and even if the ink mist is united, it slides down from the discharge port forming surface at the stage of minute droplets, and it is large enough to affect the discharge accuracy. This is considered to be because the droplets do not stay around the discharge port. That is,
Small ink droplets adhere on the ejection port forming surface,
There is almost no stagnation of ink droplets around the ejection port that affects ejection, and a good effect of ejecting ink droplets can be obtained.

[0008]

As one means for achieving high-speed printing or printing in an ink jet printing apparatus, there is a means for increasing the number of times ink is ejected from an ejection port per unit time. For example, when a pulse signal is applied to an electrothermal transducer and driven to obtain ink ejection energy, high-speed recording can be achieved by using a high-frequency pulse having a higher wavelength.

However, when the electrothermal transducer is driven at a higher frequency with a higher wavelength, even if the above-described ejection port forming surface is subjected to the water repellent treatment, the ejection failure due to the adhesion of the ink droplets on the ejection port forming surface occurs. The case that occurred again became remarkable.

As a cause of this, it can be pointed out that an ink jet recording head which can be driven at a high frequency has a large meniscus overflow of ink. Meniscus overflow means that immediately after an ink droplet is ejected from the ejection port, a gap is formed in the ejection port for the ejected ink drop, and ink is resupplied from the liquid chamber side to fill this gap. This is a phenomenon in which when (refilling) is performed, the liquid surface (meniscus) of the ink in the ejection port protrudes outside the ejection port. To briefly explain this phenomenon, after the ink droplet is ejected, the ink is refilled in the liquid path by a capillary phenomenon, but the ink momentarily protrudes from the ejection port forming surface due to the inertia of the fluid motion at this time. . The ejected ink is returned to the nozzle again due to the difference between the atmospheric pressure and the internal pressure of the nozzle, and finally forms an ink meniscus in the discharge port. This phenomenon is called overflow.

In the case of an ink jet recording head capable of printing with a high-frequency pulse, such an overflow is likely to occur because the refill time is short and the inertia is easily affected. As a result, when the ejection port forming surface is subjected to the water repellent treatment, the ink overflowing from the ejection port to the ejection port forming surface is divided into fine droplets on the water repellent treatment surface around the ejection port, As a result, fine ink droplets remain around the ejection openings. It is considered that a phenomenon that ejection failure occurs due to the remaining ink droplets and good printing cannot be obtained occurs.

As described above, the technique of performing the water-repellent treatment on at least the area including the edge of the opening of the discharge port on the discharge port forming surface is required to increase the frequency of the print signal in the high-frequency driving to further increase the printing speed. Not always enough.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an ink jet recording head having a structure capable of ensuring the stability of ejection even when ink is driven at a high frequency, and an ink jet recording head using the same. To provide a recording device.

[0014]

According to the present invention, there is provided an ink jet recording head comprising a liquid path, a discharge port communicating with the liquid path, and a discharge energy generating element for discharging ink in the liquid path from the discharge port. And, in an ink jet recording head having an ejection port forming surface on which the ejection port opens, surrounding the ejection port on the ejection port forming surface, and making the inside of the ejection port peripheral region including the opening edge of the ejection port hydrophilic. The outside of the peripheral area of the discharge port is made water-repellent, and the longest opening width of the discharge port is L.
_M , when the width of the peripheral area of the discharge port is W, W <(L _M
/ 2).

In the present invention, the peripheral area (peripheral area of the discharge port) around the edge of the discharge port opening on the discharge port forming surface is made hydrophilic,
By making the area outside the area water-repellent, it is possible to prevent the formation of ink droplets that affect the ejection accuracy around the ejection port even when high-frequency driving is performed, and to stabilize ink ejection.

The structure of the present invention is suitable for an element for generating thermal energy as an ejection energy generating element, and particularly for an ink jet recording head which performs high-frequency driving using an electrothermal converter. An ink jet having a structure in which bubbles are generated by heat given to ink filled in a liquid path from a generating element to discharge ink from a discharge port, and bubbles generated at the time of discharging ink communicate with the atmosphere outside the discharge port. It can be particularly suitably applied to a recording head.

The ink jet recording head having the above configuration can be mounted on a recording head carriage to constitute an ink jet recording apparatus. A known configuration can be used as the configuration of the recording apparatus other than the recording head.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of an ink jet recording head of the present invention as a partial perspective view from a discharge port forming surface side including a cross section along a liquid path. This ink jet recording head includes at least a liquid chamber 9, a liquid path 5, and a discharge port forming surface 6 on a substrate 4 on which a discharge energy generating element 2 is disposed.
The outer peripheral region 7 including the opening edge of the discharge port 1 on the discharge port forming surface 6 is a hydrophilic region, and the outside thereof is a water-repellent region. It has become. Known structures and constituent materials of each part of the ink jet recording head can be used. The wall member 3 in the illustrated example is configured such that the structure of the liquid chamber 9, the liquid path 5, and the discharge port forming surface 6 can be formed integrally, but these parts are formed by independent members. It may be something.

In the present invention, as shown in FIG. 1, the peripheral area 7 including the opening edge of the discharge port 1 is formed as a hydrophilic surface area. Width (W) of this peripheral area 7
Is 以下 or less, preferably 好 ま し く or less of the opening width (L) of the discharge port 1.

The outlet 1 may have a rectangular or circular cross section perpendicular to the axial direction. FIG. 2 shows an example where the cross section of the discharge port 1 is circular. The ink jet recording head shown in FIG. 2 has a structure in which at least a liquid chamber (not shown), a liquid path 5 and a top plate 8 for forming a discharge port forming surface 6 are joined to a substrate 4 on which the discharge energy generating elements 2 are arranged. The peripheral region 7 including the opening edge of the discharge port 1 on the discharge port forming surface 6 is formed as a hydrophilic region, and the outside thereof is formed as a water-repellent region.
Known structures and constituent materials can be used for each part of the ink jet recording head. In the example shown in FIG. 2, the width (W) of the peripheral region 7 is １ ／ of the inner diameter (diameter: R) of the discharge port 1.
Or less, preferably 1/4 or less.

When the diameter of the discharge port varies depending on the direction of the opening surface, for example, when the diameter is rectangular as shown in FIG. 3, the width of the peripheral region 7 (W: the opening edge 1a of the discharge port 1) (The distance from the periphery of the peripheral region 7 to the outer periphery) may be set to be equal to or less than １ ／ of the longest width (L _M ) of the opening of the discharge port 1.

The formation of the peripheral region of the hydrophilic discharge port on the discharge port forming surface can be performed by laser irradiation processing, UV / O ₃ processing, plasma processing, or the like. The water-repellent region provided outside the peripheral region can be formed by applying a water-repellent by a spin coating method, a transfer method, or the like.

As described above, by maintaining the hydrophilicity of the peripheral area including the opening edge of the discharge port, the ink overflowing from the discharge port to the peripheral area due to the overflow of the ink when the ink jet recording head is driven at a high frequency. Is
Since this peripheral region is hydrophilic, it is returned to the discharge port very efficiently by the surface tension without being divided into small droplets. That is, when the peripheral area is water-repellent, it is possible to prevent the ink overflowing from the ejection port from being divided and made into small droplets and remaining there. Even if the ink overflows to the outside of the peripheral region and ink droplets are generated there, since the ink droplets are formed as a water-repellent surface, the droplets do not easily flow out and remain. Even if a small droplet remains, it does not remain at a position in contact with the opening of the discharge port, and discharge stability can be ensured.

As described above, according to the configuration of the present invention, when the meniscus is stable, that is, before the next ink droplet is ejected, a state in which minute ink droplets hardly stay around the ejection port is always maintained. Can be. Further, by performing a water-repellent treatment on the ejection port forming surface adjacent to the above-described region, it is possible to avoid the influence of ejection failure due to ink mist.

The effect of the configuration of the present invention described above will be described in detail below, following the process at the time of discharging ink droplets. 4 shows a case where the configuration according to the present invention is applied, FIG. 5 shows a case where the periphery of the discharge port including the end of the discharge port has water repellency, and FIG. 6 shows a case where the discharge port forming surface is hydrophilic and has been subjected to a water repellent treatment. FIG. 4 is a diagram schematically illustrating a cross section when the nozzle portion of the ink jet recording head is cut along a plane perpendicular to a discharge port forming surface when no nozzle is provided. Each drawing represents a state in which the discharge state from before discharge to the completion of refilling is observed at appropriate intervals, and the progress of the time is shown in each figure as (a) → (b) → (c) → (d). →
The order is (e) → (f) → (g). In these figures, 1 is a discharge port, 2 is an electrothermal conversion element (thermal energy generating element), 3 is a wall portion forming a liquid chamber, 5 is ink,
Numeral 6 denotes a water-repellent film, numeral 7 denotes a hydrophilic region, and numeral 9 denotes an ink droplet stagnating on the ejection port forming surface.

The ink jet recording head in the case where the ejection forming surface is hydrophilic and has not been subjected to the water repellent treatment, as shown in FIG. The ink mist resulting from the ejection of the ink adheres to the ejection formation surface, and stagnates the ink droplet 9 on the ejection formation surface. If the ink is ejected in this state, the ink droplets fly in a direction deviated from the normal trajectory as shown in FIG. 4D, thereby deteriorating the print quality. Even if the refill is completed as it is, the overflowing ink (FIG. 4F) comes into contact with the ink droplet 9 remaining around the ejection port and is drawn in the direction of the ink droplet 9, and becomes larger. There is a risk of forming ink droplets and ink pools.

On the other hand, as shown in FIG. 5, the ink jet recording head that maintains the area around the ejection port on the ejection port forming surface including the ejection port end to be water repellent before ejection (FIG. 5A).
It can be seen that the ink droplets 9 adhered to the ejection port forming surface by the ink mist are present in the form of fine particles due to the water-repellent film, but are at positions where they do not directly affect the ejection. However, when the ink overflows from the ejection port due to an overflow at the time of refilling (FIG. 5F), the contact angle of the ink on the water-repellent film is large, so that the ink is likely to be partially cut around the ejection port. At the end of refill (Fig. 5 (g))
This causes minute ink droplets to be left around the discharge port. For this reason, the influence is exerted at the time of the next ink droplet ejection, and the print quality is deteriorated. In the case of the present invention, as shown in FIG.
Before the ejection (FIG. 4A), the ink droplets 9 adhered to the ejection port forming surface by the ink mist are present in the form of fine particles due to the water-repellent film, but are located at a position that does not directly affect the ejection. . In addition, the ink overflowing from the ejection port due to the overflow during refilling (FIG. 4 (f)) does not enter the water-repellent region due to the boundary between water-repellent and hydrophilic, and the contact angle in the hydrophilic region is small. The ink is not divided and scattered around the discharge port, does not contact or coalesce with the ink droplet 9 attached to the discharge port forming surface due to the ink mistake, and is extremely efficient only by the surface tension of the ink. Again returns to the inside of the nozzle. Therefore, according to the configuration of the present invention, it is possible to provide an ink jet recording head capable of always performing a stable discharge while maintaining a good condition around the discharge port.

In an ink jet recording head to which the structure of the present invention can be more suitably applied, the liquid path is formed by generating bubbles in the ink supplied from the thermal energy generating element to the ink filled in the liquid path. And a structure having a structure in which bubbles generated at the time of discharging ink are communicated with the atmosphere outside the discharge port.
The characteristics of the ink jet recording head having such a liquid path configuration include good thermal efficiency, stability of the volume of flying droplets, and high-frequency driving. As a configuration of the inkjet recording head, for example,
JP-A-54-161935, JP-A-61-185
455, JP-A-61-249768, JP-A-4-10940, and JP-A-4-10941 can be used. As one example, there is a configuration in which an electrothermal conversion element is arranged close to a discharge port so that bubbles generated at the time of heat generation communicate with the atmosphere outside the discharge port. The effect when the configuration of the present invention is applied to the ink jet recording head having such a configuration will be described below.

FIGS. 7, 8 and 9 show the discharge state of the method in which the bubbles are communicated with the outside air. Each figure is a view to which the present invention is applied, a view in which a discharge port forming surface is subjected to a water-repellent treatment,
The ejection port forming surface is subjected to a hydrophilic treatment.
Is a discharge port, 2 is an electrothermal conversion element (thermal energy generating element), 3 is a wall portion forming a liquid path and a liquid chamber, 5 is ink, 6 is a water-repellent film, 7 is a hydrophilic film, and 9 is a discharge film. Ink droplets stagnating on the outlet forming surface. Regardless of the ejection method, at the time of ejection (for example, each (b) of FIGS. 4 to 9), ink overflows from the ejection port formation surface. In the case of a discharge method in which bubbles are not communicated with the outside air, as shown in (c) and (d) of FIGS. 4 to 6, the main droplet is formed while the trailing end of the discharged droplet continuously narrows at the position of the discharge port. To go. Even at the time of this ejection, the ink overflowing from the ejection opening forming surface causes the ink to overflow from the ejection opening end, but the excess ink is absorbed by the rear end portion of the ejection droplet described above. It is hardly left around the discharge port before refilling.

However, in the case of the discharge method in which the bubbles are communicated with the outside air, the bubbles are forcibly divided before the discharged droplets absorb the ink that has protruded around the discharge ports (see FIG. (D) 7 to 9) It is easy to leave ink around the discharge port. When the discharge port forming surface is subjected to the water repellent treatment, the ink is immediately made into a spherical shape by the water repellent film and can be moved (FIG. 8D). May affect subsequent ejection.

In contrast to the above-described problem of the method of communicating air bubbles with the atmosphere, in the ink jet recording head of the present invention, immediately after ejection, droplets separated by air bubbles stay around the ejection port (FIG. 7 (d)). )), Does not move due to hydrophilicity. In other words, it stays as a minute droplet,
They do not touch each other. At the time of refilling after the ejection, the fine droplets around these ejection ports come into contact with the ink overflowing from the ejection port forming surface due to overflow (FIGS. 7E and 7F), and the meniscus moves to the ejection port forming surface. At the same time as it is formed, it is absorbed into the nozzle by the surface tension (FIG. 7 (g)) and does not affect the subsequent ejection.

Further, in such a system in which the bubbles generated in the liquid path at the time of discharge are communicated with the atmosphere outside the discharge port, the inertial flow path resistance between the electrothermal transducer and the discharge port causes the ink jet recording not to communicate with them. It is smaller than the head. The inertial flow path resistance is a parameter that is very sensitive to the movement of the meniscus.If this value is small, the amount of ink that overflows from the discharge port forming surface during refilling increases,
It is easy to overflow. The inertial flow path resistance R of the fluid between the electrothermal transducer and the ejection port is represented by the following equation: ink density ρ, ejection port area S, and distance between the electrothermal transducer and the ejection port.
Can be roughly expressed by the formula: R to ρl / S. As described above, it can be seen that the inertial flow path resistance and the amount of overflowed ink have a close relationship,
From the viewpoint of finding the conditions for achieving the present invention more effectively, it is important first of all how much the projection of the overflowed ink drawn on the ejection port forming surface has advanced from the ejection port end. The projection of the overflowed ink on the discharge port forming surface is substantially determined by the physical properties of the ink, the driving conditions, the size and shape of the liquid flow path, the position of the electrothermal conversion element, and the like. Relationships can only be obtained by rules of thumb. In the present invention, the dimensions of the discharge port closely related to the inertial flow path resistance,
From the experimental result that the amount of overflowed ink and the projection size of the projection on the discharge port forming surface from the discharge port end are the most sensitive, it was found that the hydrophilic area of the present invention was changed by the discharge port diameter. From this, it was found that the ejection condition of the ink droplets was very good by making the region including the distance up to の of the diameter of the ink ejection opening measured from the end of the ink ejection opening hydrophilic.

[0033]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. Example 1 An ink jet recording head having the configuration shown in FIG. 1 was prepared by a standard method according to the following standard except for the surface treatment of the ejection port forming surface. Size of discharge port 1 (L in FIG. 1): 20 μm × 20 μm
Arrangement density of discharge ports: 360 dpi Width of peripheral area 7 (W in FIG. 1): 5 μm Distance between discharge port forming surface 6 and upper surface of substrate 4: 20 μm Hydrophilic peripheral area 7 on discharge port forming surface 6 The water-repellent region outside the surface was formed by applying a water-repellent to the entire surface of the discharge port forming surface 6 by spin coating, and then irradiating an excimer laser to a portion to be hydrophilized.

This ink jet recording head has a configuration in which a bent ink flow path 5 is provided, and ink droplets are ejected from an ejection port 1 provided in parallel to an ejection energy generating element 2 composed of an electrothermal transducer. Have. The distance between the ejection port forming surface 6 and the surface on which the liquid passage 5 of the substrate 4 is formed is 20 μm as described above, and when the ejection energy generating element 2 is driven by a recording signal, the ejection energy generating element 2
Bubbles are generated in the ink above, and ink droplets are ejected from the ejection port 1, and the bubbles communicate with the atmosphere.

Using this ink jet recording head, an ink droplet is ejected from one ejection port by driving the ink at 10 kHz to a recording medium placed in parallel at a distance of 1.0 mm from the ejection port forming surface. 1.0m / s at the same time
FIG. 10A shows the printing result when the ink jet recording head was moved in parallel with the recording medium. In the figure, the crosses indicate ideal landing positions.

The same operation was performed on an ink jet recording head of the same shape in which the entire surface excluding the ejection ports on the ejection forming surface was water-repellent and an ink jet recording head of the same shape in which the ejection port forming surface was hydrophilic. Are shown in FIGS. 10B and 10C, respectively.

To obtain a higher definition and higher quality image,
It is required that printing be performed so that dot intervals are as constant as possible and each dot is on a straight line. Obviously, this embodiment is closest to the requirement and provides a stable ejection state. When the amount of deviation from the regular landing position in each ink jet recording head was measured, in the present embodiment, it was ± 8.0 μm in the x direction in FIG. X is water-repellent
± 21.2 μm in the direction, 19.8 μm in the direction, and ± 40.2 μmy in the x direction
± 34.6 μm in the direction.

Example 2 An ink jet recording head having the structure shown in FIG. 2 was prepared by the usual method according to the following standard except for the surface treatment of the discharge port forming surface. Discharge port diameter (R: diameter in FIG. 2): 30 μm Arrangement density of discharge ports: 360 dpi Width of peripheral region 7 (W in FIG. 2): 10 μm Discharge port forming surface 6 and discharge energy generating element 2 (electrothermal conversion element) In addition, in the hydrophilicity of the peripheral region 7 and the water-repellent treatment of the region outside the peripheral region 7, a water-repellent agent is applied to the entire surface of the discharge port forming surface 6 by spin coating, and then an excimer laser is irradiated to a portion to be hydrophilicized. By doing that.

When printing was performed on this ink jet recording head using Example 1, good printing could be obtained also in this example.

[0040]

As described above, according to the present invention,
It is possible to provide an ink jet recording head that always keeps a good state with almost no stagnation of ink droplets around the ejection port, and thus can perform stable ejection. Further, the present invention is applied to an ink jet recording head of a system in which air bubbles are communicated with the outside air, and has an effect that even minute ink droplets around an ejection port caused by forcible division of ink by air bubbles at the time of ejection do not remain. is there.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a size relationship between a discharge port and a hydrophilic region provided around the discharge port.

FIG. 4 is a diagram illustrating a process of ejecting ink droplets from ejection ports of an inkjet recording head according to the present invention.

FIG. 5 is a diagram illustrating a process of discharging ink droplets from a discharge port of an inkjet recording head.

FIG. 6 is a diagram illustrating a process of discharging ink droplets from a discharge port of an inkjet recording head.

FIG. 7 is a diagram illustrating a process of ejecting ink droplets from ejection ports of the ink jet recording head of the present invention.

FIG. 8 is a diagram illustrating a process of ejecting ink droplets from ejection ports of an inkjet recording head.

FIG. 9 is a diagram illustrating a process of discharging ink droplets from a discharge port of an inkjet recording head.

FIGS. 10A and 10B are diagrams schematically comparing the landing positions of ink droplets on a recording material, wherein FIG. 10A is a case according to the configuration of the present invention, and FIGS. .

FIG. 11 is a diagram illustrating a configuration of a conventional inkjet recording head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge port 2 Discharge energy generating element 3 Wall constituting liquid path etc. 4 Substrate on which discharge energy generating element is arranged 5 Liquid path 6 Discharge port forming surface 7 Peripheral area including hydrophilic discharge port opening edge 8 Top plate 9 Liquid chamber

Claims (5)

[Claims] 1. A liquid path, a discharge port communicating with the liquid path, a discharge energy generating element for discharging ink in the liquid path from the discharge port, and a discharge port forming surface on which the discharge port opens. In the ink jet recording head having the above, surrounding the discharge port of the discharge port forming surface, the inside of the discharge port peripheral region including the opening edge of the discharge port is made hydrophilic, and the outside of the discharge port peripheral region is made water repellent. the aperture largest width L _M of the discharge port, the width of the discharge port peripheral area when the _{W, W <(L M /} 2) the ink jet recording head characterized by satisfying the relationship. 2. The ink jet recording head according to claim 1, comprising a plurality of units each having the liquid path, the energy generating element, and the discharge port. 3. The ink jet recording head according to claim 1, wherein the discharge energy generating element is a heat energy generating element that generates heat energy for discharging ink. 4. The liquid path discharges ink from the discharge port by generating bubbles by heat given to the ink filled in the liquid path from the thermal energy generating element,
4. The ink jet recording head according to claim 3, wherein a bubble generated at the time of ink ejection has a structure communicating with the atmosphere outside the ejection port. 5. An ink jet recording apparatus comprising the ink jet recording head according to claim 1.