JP3158688B2 - Inkjet head - Google Patents

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 for printing by discharging ink droplets from nozzles.

[0002]

2. Description of the Related Art Conventionally, a plurality of ink flow paths are provided on one flow path substrate, and a nozzle,
A so-called on-demand type multi-layer in which a pressurizing chamber is arranged in a plane and an ink discharge means such as a piezoelectric element is provided in a flow path substrate lid joined to the flow path substrate so as to face the pressurizing chamber. There is a nozzle inkjet head.

In general, since the cross-sectional area of the pressurizing chamber is larger than the cross-sectional area of the nozzle, the two cannot be arranged at the same pitch. To spread out and arrange in a fan shape (for example,
No. 9-3150), and a configuration in which nozzles arranged at high density are perpendicular to the ink flow paths and the ink flow paths are radially arranged (for example, Japanese Patent Publication No. 59-4309). In each case, the lengths of the plurality of ink flow paths are different, and the cross-sectional area of the vicinity of the nozzle is smaller than that of the other ink flow paths and the flow resistance is larger. Due to the difference, the size and the ejection speed of the ink droplet 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 was required. In addition, it takes a long time to fill the ink after the ink is ejected, the response frequency is not sufficiently increased, and it is difficult to achieve a high speed.

In Japanese Patent Publication No. 59-3150, the portion from the outlet of each pressurizing chamber to the nozzle has a long flow path with a large cross-sectional area, and a short flow path with a small cross-sectional area. The problem is to be solved by making the flow path resistance of the entire ink flow path the same.

[0005]

In each of the prior arts described above, the depth of the ink flow path is substantially the same in each portion, and the cross-sectional area is different due to the difference in width. As described above, the cross-sectional areas of the respective portions of the ink flow path are different from each other. Particularly, in the vicinity of the nozzle, the pitch between the nozzles is small, so that the width of the ink flow path is narrow, and therefore, the cross-sectional area is small and the flow path resistance is large. Therefore, there has been a problem that it is difficult for the ink to flow, the ejection performance is not sufficient, and the efficiency of ink supply is low.

Accordingly, it is an object of the present invention to achieve high resolution and high speed by making the cross-sectional areas of the respective portions of the ink flow paths substantially the same, achieve a uniform image to achieve a high quality image, and reduce the cost. To provide

[0007]

According to the present invention, a plurality of nozzles for discharging ink droplets are provided.
A pressure chamber that communicates with a nozzle via an ink flow path is stacked on a flow path substrate formed at a pitch wider than the pitch between adjacent nozzles, and on a side of the flow path substrate that seals the ink flow path and the pressure chamber. In the ink jet head provided with the flow path substrate lid, the ink flow path, the wide portion is shallow in the thickness direction of the flow path substrate so that the cross-sectional area in the longitudinal direction is substantially the same,
The narrow part is formed deep in the thickness direction of the flow path substrate.

[0008]

FIG. 1 shows the overall structure 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 the ink reservoir 2. …Until,
The plurality of ink channels 4 communicate with each other. Channel substrate 1
A flow path substrate lid 5 (FIG. 3) is joined to the upper surface of the piezoelectric element 6. Is stuck.

Next, the structure of the ink flow path 4 will be described with reference to FIGS. Nozzle 3 from ink reservoir 2
A pressure chamber 4a is provided at the center of the ink flow path 4 between the ink chamber 4 and the rear flow path 4b from the ink reservoir chamber 2 to the inlet of the pressure chamber 4a. And the length of each rear flow path 4b is made substantially the same. The rear passage 4b communicates with the ink reservoir 2 via the restriction 4c. The rear flow path 4b has substantially the same width w1 over each part of the flow path, and has a depth h1.
Are also formed almost uniformly.

A front flow path 4d between the nozzle 3 and the outlet of the pressurizing chamber 4a has a flow path 4d1 near the outlet of the pressurizing chamber.
It is a wide part with the same width w1 as the width of the rear channel 4b,
In the flow path 4d2 near the nozzle, it cannot be as large as the width w2 due to the relationship of the nozzle pitch, and is a narrow portion. 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. 5, the narrow channel 4d2 is formed as deep as the depth h2. 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 x
Since it is the depth, it is set so that w1 × h1 = w2 × h2.

When a drive signal is supplied from a drive circuit (not shown) to the electrodes on both sides of the piezoelectric element 6 when ink is ejected, the piezoelectric element 6 curves toward the pressurizing chamber and reduces the volume of the pressurizing chamber 4a. 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 has the same cross-sectional area at all positions, the flow path resistance is the same, and the ink flows uniformly and quickly and is discharged 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 2 is supplied to the pressurizing chamber 4a through the rear flow path 4b due to the capillary phenomenon, but also at this time, the cross-sectional area of each part of the rear flow path 4b is the same and the flow path resistance is reduced. 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 a rectangular shape as shown in the drawings, but may be an inverted trapezoidal shape, a cross-sectional shape with a curved bottom, a triangular shape, or the like, and various other cross-sectional shapes are possible.

[0013]

As described above, according to the present invention, a plurality of nozzles for ejecting ink droplets and a pressurizing chamber communicating with the nozzles via an ink flow path are formed at a pitch wider than the pitch between adjacent nozzles. Head provided with a flow path substrate and a flow path substrate lid laminated on the side of the flow path substrate that seals the ink flow path and the pressurizing chamber, the ink flow path has a longitudinal sectional area. The wide part is formed shallow in the thickness direction of the flow path substrate, and the narrow part is formed deep in the thickness direction of the flow path substrate, so that the resolution of the nozzles that eject ink droplets is increased. Therefore, in an inkjet head in which the arrangement pitch of the nozzles is more integrated than the arrangement pitch of the pressurizing chambers having a desired width necessary for pressurizing the ink, the substantial flow path resistance of each ink flow path is reduced by each cross section. Can be the same Therefore, the ink is uniformly discharged from each nozzle, and the ink flows quickly without any stagnation in the ink flow path, so that the ink filling time is reduced, and the ink discharge characteristics and the response frequency can be improved. . Therefore, there is an effect that a printer capable of high-resolution and high-speed printing can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view of a channel substrate according to an embodiment of the present invention.

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

FIG. 3 is a cross-sectional view taken along a flow channel.

FIG. 4 is an enlarged sectional view taken along the line AA of FIG. 2;

FIG. 5 is an enlarged sectional view taken along the line BB in FIG. 2;

[Explanation of symbols]

 Reference Signs List 1 flow path substrate 3 nozzle 4 ink flow path 4a pressurizing chamber 5 flow path substrate lid 6 pressing means w1, w2 width h1, h2 depth

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-179552 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/045 B41J 2/055

Claims (1)

(57) [Claims] 1. A plurality of nozzles for ejecting ink droplets, before
The pressure chamber communicating with the nozzle through the ink flow path
Flow formed at a pitch wider than the pitch between the nozzles
Path substrate, the ink flow path and the pressure chamber of the flow path substrate
In an ink jet head having a flow path substrate lid laminated on a sealing side, the ink flow path has a wide portion in a thickness direction of the flow path substrate so that a cross-sectional area in a longitudinal direction is substantially the same. Shallow,
An ink jet head, wherein the narrow portion is formed deep in the thickness direction of the flow path substrate.