JPH11314369A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an ink drop from flowing into an ejection opening and having effect on ink ejection by providing a water repellent region around each ejection opening on the surface where a plurality of ejection opening arrays are formed and providing a hydrophilic region around an adjacent ejection opening. SOLUTION: A plurality of ejection opening arrays are juxtaposed on the ejection opening forming plane of an ink jet recording head and a water repellent region 3 is arranged around each ejection opening while a hydrophilic region 8 is arranged around each adjacent ejection opening. Adjacent ejection openings 2 with regard to the ejection opening array are arranged while shifting the position in the direction normal to the extending direction of array. A large number of ejection openings 2 are divided into a plurality of groups and driven simultaneously for each group. When a large quantity of ink drop adheres to the hydrophilic region 8 on one side of the array, the ink drop is caused to overflow effectively to the hydrophilic region 8 on the other side thus preventing the ink drop from passing over the ejection opening 2 surely.

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 an improved discharge port forming surface enabling stable discharge and a recording apparatus using the ink jet recording head.

[0002]

2. Description of the Related Art The ink jet recording method is a non-impact recording method that hardly generates noise during recording among various recording methods known at present, and is noteworthy in that high-speed recording is possible. It has been evaluated as an effective recording method, and is widely and generally used.

In such an ink jet recording apparatus, the film boiling recording method by heat generation is practically useful because the ink discharge direction from the discharge port communicating with the liquid path is extremely stable. With the expansion of the application range of the ink jet recording method and higher performance, the demand for the stability of the ink ejection direction has been further enhanced. One of the problems in further improving the ejection stability is that when the ink droplets are ejected from the ejection openings, fine ink particles called ink mist are generated, and the ink droplets are gathered. In this case, a predetermined amount of ejection stability may be impaired by the formation of a liquid pool around the nozzle and blocking the ejection opening.

In the prior art, in order to solve this problem, a water-repellent treatment has been performed on a discharge port forming surface having ink discharge ports. 4 and 5 show an example of a discharge port forming surface of an ink jet (recording) head having such a configuration. In each figure, 1 is a discharge port forming surface, 3 is a water repellent film,
4 is an ink supply port, 5 is a grooved top plate formed integrally with a liquid chamber (not shown), a flow path (not shown), and a discharge port forming surface 1, 2 is a discharge port, and 6 is an ink discharge port. 2 is a substrate having an element for discharging from the substrate. In the configuration of FIG.
A water-repellent film 3 is formed on almost the entire surface of the discharge port forming surface 1, and a sufficient effect is obtained in an ink jet (recording) head having a relatively small discharge ink amount. Furthermore, when printing is performed continuously, for a long time, with high-frequency driving, high printing speed, and high duty, the amount of generated ink mist is large, and ink droplets may gradually stagnate on the ejection port forming surface. Was.

In this case, ink droplets adhere to the discharge port forming surface and move to the discharge port side, and if the discharge port 2 is closed, discharge may not be performed accurately. Means of providing a partially hydrophilic portion to temporarily hold ink droplets and stabilize ejection have been put to practical use. FIG. 5 shows an example of the conventional example, in which a water-repellent film 3 is provided on the surface of the discharge port forming surface 1 excluding the hydrophilic region 7, and is adjacent to the water-repellent region in a direction away from the discharge port 2, In addition, a strip-shaped hydrophilic region 7 is provided on both sides along the arrangement region of the row including the discharge ports 2.
Is arranged.

[0006]

However, in the conventional example described above, for example, in a head having two rows of discharge ports as shown in FIG. 3A, a large amount of ink droplets adhere between the rows of discharge ports. Then, there is a problem that the ink overflows from the hydrophilic region 7 provided partially around the ejection port 1 (see FIGS. 3B to 3D). This is apparent from comparison with a head having one row of discharge ports on the same plane as shown in FIG. That is, two discharge port arrays are on the same plane.
The ink droplets generated by the tearing of the ink droplets ejected at the time of ejection on the ejection opening array A side are discharged from the ejection opening array B
This is because the ink mist moves to the side to affect each other and the ink mist is more easily collected between the ejection port arrays. In addition, the mist adhering to the head surface tends to collect in the hydrophilic region 7 due to the movement of the mist due to the coalescence of the mist and the air current caused by the movement of the carriage on which the head is mounted. Due to the overflow caused by such factors, ink droplets may adhere to the ejection port portion, causing the ejection and ejection failure.

The present invention has been made in view of such problems in the prior art, and is suitable for printing under a condition of discharging a larger amount of ink per unit time or a condition of performing high-speed driving at a higher speed. It is an object of the present invention to provide an ink jet recording head and a recording apparatus using the same, which are sufficiently applicable.

[0008]

According to the present invention, there is provided an ink jet recording head provided with a liquid path, a discharge port communicating with the liquid path, and a liquid path, wherein the ink in the liquid path is discharged. An ink jet recording head having a large number of units having discharge energy generating elements for discharging from an outlet, and a row of discharge ports of each unit being arranged on a discharge port forming surface; It is characterized in that the area around each of the outlets forming the outlet row is a water-repellent area, and a hydrophilic area is provided between the water-repellent areas around the adjacent outlets.

The improved structure of the discharge port forming surface in the present invention is more effective when a plurality of discharge port arrays are arranged in parallel. The inkjet recording head having this configuration can be mounted on a carriage for a recording head to constitute an inkjet recording apparatus. A known configuration can be used as the configuration of the recording apparatus other than the recording head.

According to the structure of the present invention, even if ink droplets adhere to the hydrophilic regions provided in parallel on both sides of the discharge port array on the discharge port forming surface and overflow, the area around the discharge ports is water repellent. By dividing the water-repellent area of the adjacent ejection port into a hydrophilic area as an area, ink droplets flow into the ejection port,
Influence of ink ejection therefrom is effectively prevented.

Further, even when a plurality of ejection opening arrays are arranged in parallel, even when the amount of ink droplets adhering to the ejection opening forming surface increases, the ink droplets attached to the hydrophilic region can be effectively discharged. Can be. In other words, even when a plurality of ejection ports are arranged in parallel on the same plane, the ejection of an adjacent ejection port array via ink droplets adhering to the ejection port forming surface during ejection operation in one ejection port array. Interaction that affects the performance can be cut off, and it is possible to prevent the ejection direction from being distorted at the ejection port due to the overflow of the ink droplet and the ejection failure.

[0012]

FIG. 1 is a plan view showing an example of a discharge port forming surface in an ink jet recording head of the present invention. Two rows of discharge ports are provided in parallel on the discharge port forming surface 1, and a water-repellent region 3 is provided around each discharge port 2 by performing a water-repellent process by applying a water-repellent film or the like. ing. Further, the surface of the discharge port forming surface 1 other than the water repellent region 3 is formed so as to have hydrophilicity. As a result, the discharge port row is sandwiched between the adjacent discharge ports in each discharge port row. A structure in which a hydrophilic region is formed is obtained.

Further, in the discharge port array in the illustrated example, the discharge ports are not arranged linearly in the direction in which the rows extend, and the positions of the discharge ports adjacent in the direction perpendicular to the direction in which the rows extend are determined. It has been shifted. The ink jet recording head having such an arrangement of the ejection ports is particularly suitable for a case where a large number of ejection ports are dividedly driven. That is,
A large number of discharge ports are divided into a plurality of groups, and each group is driven simultaneously. This split drive has the advantage that the current flowing simultaneously can be reduced. When performing this division drive, since the ejection timing between the ejection ports belonging to different groups is different, when the inkjet recording head is mounted on a carriage that moves at a constant speed on the inkjet recording apparatus, a large number of If the ejection openings form an ejection opening array in which the ejection openings are arranged in a straight line, it is difficult to obtain linearity in a vertical line to be printed. Therefore, by adopting a configuration in which the discharge port position is shifted by the amount of the shift, linearity can be easily obtained. For this reason, in the example of FIG. 1, the ejection ports are shifted in a direction (x direction) perpendicular to the direction in which the ejection port array extends.

FIG. 2 is an enlarged view of the vicinity of the discharge port. By dividing the size of the water-repellent region 3 and the space between adjacent water-repellent regions 3,
The width and the like of the strip-shaped hydrophilic region 8 provided so as to bridge the hydrophilic regions A and B on both sides of the ejection port array can be selected according to desired recording conditions and the like in the arrangement of the ejection ports. .

The water-repellent region and the hydrophilic region in the present invention can be formed by a known method. Also,
A known configuration can be used for each part of the inkjet recording head of the present invention.

As shown in FIGS. 1 and 2, a strip-shaped hydrophilic region 8 is provided between adjacent discharge ports constituting a discharge port array, so that one side of the discharge port row (for example, FIG. Even when a large amount of ink droplets are attached to the hydrophilic area (area A) and are likely to overflow, the hydrophilicity on the other side (for example, the area B in FIG. The ink droplets are effectively overflowed to the area and discharged. At this time, since the periphery of the ejection port 1 is a water-repellent area, the ink droplet does not pass over the ejection port 1. As a result, it is possible to prevent the ejection openings from being closed due to overflow of the attached ink droplets when the conventional band-shaped hydrophilic region is provided in parallel with the ejection opening array. Further, when a plurality of ejection opening arrays are arranged in parallel, the amount of ink droplets adhering to the hydrophilic region increases, so that the configuration of the present invention in which the band-like hydrophilic region 8 is provided is more effective. .

[0017]

Example 1 An ink jet recording head was manufactured using the structure shown in FIGS. The resolution of the ejection ports is 300 dpi per row, and the pitch between the two ejection ports is shifted by 600 dpi. Discharge port size is 21.5 × 22μm
Is a rectangle. The distance from the discharge port to the end of the water-repellent region 3 was 40 μm for X and 15 μm for Y shown in FIG. The distances X and Y can be selected according to the type of ink, the diameter of the ejection port, and the like. In the present embodiment, a strip-shaped hydrophilic region 8 is provided between the water-repellent regions 3 between adjacent discharge ports in one row. The width (Z) of the band-shaped hydrophilic region 8 is 84.7 μm−55.
5 μm = 29.2.

The water-repellent film 3 on the hydrophilic discharge port surface 1
Was formed by applying a water-repellent material onto a polyester film, drying the film, and then pressing the film together with the discharge port surface to transfer the water-repellent material. In addition, other configurations were manufactured by known materials and methods.

This ink jet recording head was mounted on a carriage of an ink jet recording apparatus so that a row of ejection ports intersects the scanning direction of the head, and printing was performed at a high duty using ink jet ink.
Ink droplets accumulate in the hydrophilic region between the ejection openings in the row, but are discharged through the hydrophilic region between the ejection openings, so that the ejection direction is distorted when ink is ejected from the ejection openings due to overflow of the ink droplets. And the occurrence of defective ink ejection from the ejection port did not occur.

The width (Z) of the hydrophilic region 8 between the discharge ports
Investigations to determine the dimensions of
When the width is as small as μm, the ink overflows before the ink droplets in the gaps are discharged, and the ink droplets accumulate in the water-repellent area around the discharge port, causing displacement in the discharge direction and defective discharge. Also 40 μm
When the ink droplets reach the water-repellent area around the ejection port and are repelled and move to the hydrophilic area, the ink droplets remaining in the hydrophilic area are combined with the ink droplets in the water-repellent area and ejected. It was trapped near the exit and twisted. Therefore, in this embodiment, the distance from the ejection port to the end of the water-repellent region is set to 15 μm. However, the distances Y and Z can be changed depending on factors such as the type of ink, the ejection aperture, the ejection volume, and the like.

[0021]

According to the present invention, even if an ink droplet adheres to and overflows a hydrophilic region provided in parallel on both sides of a discharge port array on a discharge port forming surface, the area around the discharge port is water repellent. By dividing the water repellent region of the adjacent ejection port into a hydrophilic area as an area, it is possible to effectively prevent ink droplets from flowing into the ejection port and affecting ink ejection therefrom.

Furthermore, even when a plurality of ejection port arrays are arranged in parallel, even if the amount of ink drops adhering to the ejection port forming surface increases, the ink drops adhering to the hydrophilic region can be effectively discharged. Can be.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a structure of a discharge port forming surface of an ink jet recording head of the present invention.

FIG. 2 is a partially enlarged view of an arrangement portion of a discharge port on a discharge port forming surface shown in FIG. 1;

FIG. 3 is a diagram illustrating a conventional example.

FIG. 4 is a diagram illustrating a conventional example.

FIG. 5 is a diagram illustrating a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge port forming surface 2 Discharge port 3 Water repellent area (water repellent film) 4 Ink supply port 5 Slotted top 6 Substrate 7 Hydrophilic area 8 Strip hydrophilic area

Claims (3)

[Claims] 1. A liquid path, a discharge port communicating with the liquid path, and a discharge energy generating element provided corresponding to the liquid path for discharging ink in the liquid path from the discharge port. In an ink jet recording head having a large number of units having a plurality of units, and a row of discharge ports of each unit arranged on a discharge port forming surface, at least the periphery of each discharge port forming the discharge port row on the discharge port forming surface is repelled. An ink jet recording head comprising a water region and a hydrophilic region provided between water-repellent regions around an adjacent discharge port. 2. The ink jet recording head according to claim 1, wherein a plurality of the ejection port arrays are arranged in parallel. 3. An ink jet recording apparatus comprising the ink jet recording head according to claim 1.