JPH0647913A - Ink jet head - Google Patents

Abstract

PURPOSE:To accomplish a high resolving power and a high speed and obtain a uniform and high-quality image by forming respective parts of ink flow paths with substantially the same cross sectional area. CONSTITUTION:A plurality of ink flow paths 4 connecting a common ink reservoir chamber 2 to a plurality of nozzles 3 are provided on a top surface of a flow path substrate 1. On the top surface of the flow path substrate 1, a flow path substrate cover is bonded. Pressurizing means are disposed on the flow path substrate cover opposedly to pressurizing chambers 4a, each of which is provided in the center part of the ink flow path 4. A rear flow path 4b formed from the ink reservoir chamber 2 to the pressurizing chamber 4a has a large width w1 and a small depth. The rear flow path 4b is connected to the ink reservoir chamber 2 through a restriction 4c. A front flow path from the nozzle 3 to the pressurizing chamber 4a is composed of a flow path 4d1 having a large width w1 and a flow path 4d2 having a small width w2 in the vicinity of the nozzle 3. The large-width flow path 4d1 is formed small in depth, and the small-width flow path 4d2 is formed large in depth. In this manner, the cross sectional areas of the flow paths are made substantially equal to each other at every part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called on-demand type ink jet head which prints by ejecting ink droplets from nozzles.

[0002]

2. Description of the Related Art Conventionally, a plurality of ink channels are provided on one channel substrate, and each ink channel has a nozzle,
A pressure chamber is arranged in a plane, and a flow path substrate lid joined to this flow path substrate is provided with an ink ejecting means such as a piezoelectric element facing the pressure chamber. There is a nozzle inkjet head.

Since the cross-sectional area of the pressurizing chamber is generally larger than the cross-sectional area of the nozzle, the two cannot be arranged at the same pitch, and the nozzles are arranged at a predetermined pitch and are spaced toward the pressurizing chamber. Configuration that spreads out and arranges in a fan shape (for example,
No. 9-3150), and a configuration in which the nozzles arranged at high density are perpendicular to the ink flow path and the ink flow paths are arranged radially (for example, Japanese Patent Publication No. 59-4309). In each case, the lengths of a plurality of ink flow paths are different from each other, and since the cross-sectional area and the flow path resistance near the nozzle are smaller than those of other ink flow paths, the ink flow path length is Due to the difference, the size and the ejection speed of the ink droplets ejected from the tip of the nozzle are different, and the uniformity of the image is deteriorated. For this reason, an electric circuit for correcting the characteristic difference between the flow paths is required. Further, it takes a long time to fill the ink after ejecting the ink, the response frequency is not sufficiently increased, and it is difficult to achieve high speed.

In Japanese Examined Patent Publication No. 59-3150, from the outlet of each pressurizing chamber to the nozzle, a long flow path has a large cross-sectional area, and a short flow path has a small cross-sectional area. An attempt is made to solve the problem by making the flow resistance of the entire ink flow path the same.

[0005]

In each of the above-mentioned conventional examples, the depth of the ink flow path is substantially the same over each portion, and the cross-sectional areas are different due to the difference in width. As described above, the cross-sectional area is different in each part of the ink flow path, and particularly in the vicinity of the nozzles, the width of the ink flow path is narrow because the pitch between the nozzles is small, and therefore the cross-sectional area is small and the flow path resistance is large. Therefore, there is a problem that the ink becomes difficult to flow, the ejection performance is not sufficient, and the ink supply efficiency is poor.

Therefore, an object of the present invention is to achieve a high resolution and a high speed by making the cross-sectional areas of the respective portions of the ink flow path substantially the same, to make the image uniform, to achieve a high quality image, and at a low cost. To provide.

[0007]

In order to achieve the above object, according to the present invention, an ink flow path for connecting a pressurizing chamber facing a pressurizing means for pressurizing ink inside and a nozzle for ejecting the ink. In an ink jet head including a flow path substrate on which is formed, and a flow path substrate lid that is joined to the ink flow path side of the flow path substrate, the ink flow path has a wide portion that is shallow and a narrow portion. Is deeply formed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the overall construction of an embodiment of the present invention. A common ink reservoir 2 is provided on the upper surface of a flow path substrate 1, and a plurality of nozzles 3 are provided from this ink reservoir 2. …Until,
The plurality of ink flow paths 4 communicate with each other. Flow path substrate 1
The flow path substrate lid 5 (FIG. 3) is joined to the upper surface of the ink jet device, and the piezoelectric element 6 serving as the ink pressurizing means is provided on the upper surface of the flow path substrate lid 5 at a position facing a pressure chamber described later. Is stuck.

The structure of the ink flow path 4 will be described below with reference to FIGS. From the ink reservoir 2 to the nozzle 3
The pressurizing chamber 4a is provided in the central part of the ink flow path 4 between the ink storage chamber 2 and the rear flow path 4b from the ink reservoir chamber 2 to the inlet of the pressurizing chamber 4a. The rear passages 4b are bent so that the lengths of the rear passages 4b are substantially the same. The rear passage 4b communicates with the ink reservoir 2 via the restriction 4c. The rear channel 4b has substantially the same width w1 and the depth h1 over the respective portions of the channel.
Are also formed almost uniformly.

The front passage 4d between the nozzle 3 and the outlet of the pressurizing chamber 4a is
The width w1 is the same as the width of the rear channel 4b and is a wide portion.
In the flow path 4d2 near the nozzle, the width w2 cannot be as large as the width of the nozzle because of the pitch of the nozzle, and the width is narrow. Therefore, as shown in FIG. 4, the wide channel 4d1 is formed to be shallow at the same depth h1 as the depth of the rear channel 4b, and as shown in FIG. Form. In this way, the cross-sectional area of the ink flow path is made substantially the same over each part of the flow path. That is, the cross-sectional area is width ×
Since it is the depth, it is set such that w1 xh1 = w2 xh2.

When a drive signal is supplied to the electrodes on both sides of the piezoelectric element 6 from a drive circuit (not shown) when ejecting ink, the piezoelectric element 6 bends toward the pressurizing chamber and the volume of the pressurizing chamber 4a is reduced. Compress. For this reason, the ink is pressurized, the ink flows toward the nozzle 3, and is ejected from the nozzle 3 to the outside to perform printing. Since the front flow path 4d is formed to have the same cross-sectional area at all positions, the flow path resistance is the same, and ink flows uniformly and quickly and is ejected from the nozzle 3. After the ink is ejected, the voltage applied to the piezoelectric element 6 becomes 0, and the piezoelectric element 6 returns to the initial state. At this time, the ink in the ink reservoir chamber 2 is supplied to the pressurizing chamber 4a through the rear passage 4b due to the capillary phenomenon. At this time, the cross-sectional area of each portion of the rear passage 4b is the same and the passage resistance is Since they are the same, the ink is uniformly and quickly supplied to the pressurizing chamber 4a, and returns the meniscus surface of the nozzle 3 to the initial state through the front passage 4d.

The cross-sectional shape of the ink flow path is shown in FIGS.
The shape is not limited to the rectangular shape shown in the figure, but may be an inverted trapezoidal shape, a curved bottom cross-sectional shape, a triangular shape, or the like, and various other cross-sectional shapes are possible.

[0013]

As described above, according to the present invention, since the cross-sectional area of the ink flow path is substantially the same over the respective parts of the flow path and therefore the flow path resistance is the same, the ink is uniform. In addition, it is possible to provide a high-resolution and high-speed printer because the ink can flow rapidly and quickly, the ink ejection characteristics can be improved, the ink filling time can be shortened, and the response frequency can be improved.

[Brief description of drawings]

FIG. 1 is a plan view of a flow path substrate showing an embodiment of the present invention.

FIG. 2 is an enlarged plan view showing one flow path.

FIG. 3 is a sectional view taken along a flow path.

FIG. 4 is an enlarged cross-sectional view taken along the line AA of FIG.

FIG. 5 is an enlarged cross-sectional view taken along the line BB of FIG.

[Explanation of symbols]

 1 flow path substrate 3 nozzle 4 ink flow path 4a pressurizing chamber 5 flow path substrate cover 6 pressurizing means w1, w2 width h1, h2 depth

Claims (1)

[Claims] 1. A flow path substrate having an ink flow path connecting a pressure chamber facing a pressure means for pressurizing ink inside and a nozzle for ejecting the ink; An ink jet head provided with a flow path substrate lid joined to an ink flow path side, wherein the ink flow path is formed such that a wide portion is shallow and a narrow portion is deep.