JP3289739B2 - 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, as an example of such an ink jet head, a nozzle plate, an intermediate plate and a back plate 13 (FIGS.
0) are sequentially laminated and fixed, and a plurality of ink flow paths are defined between a nozzle plate and an intermediate plate. This is at one end of each ink flow path,
Nozzles penetrating the nozzle plate in the thickness direction communicate with each other, and the other end of each ink flow path communicates with a throttle passage penetrating the intermediate plate in the thickness direction. This backboard 1
9 and 10, an ink inlet 13a for receiving ink supply from the cartridge case is formed in the center of the cartridge 3 and a space between the intermediate plate and the back plate 13 is provided therebetween. A common ink chamber 84 having a circular shape is formed which extends over the entire area of the space. And on the outer surface of the nozzle plate,
The same number of piezoelectric elements as the ink flow paths are fixed at positions corresponding to the respective ink flow paths. In this prior art, when the ink is injected into the head, the ink supplied from the ink inlet 13a accumulates in the common ink chamber 84, and further flows from the ink chamber 84 through each of the throttle passages and each of the ink flow paths. The ink is filled up to each nozzle, thereby filling the entire inside of the head with ink.

[0003]

However, in the above prior art, the common ink chamber 84 formed between the intermediate plate and the back plate 13 has a large-area circular shape extending over the entire space therebetween. When the ink is injected, the ink supplied from the ink inlet 13a is supplied to the common ink chamber 81.
In some cases, air bubbles may not be uniformly spread in the radial direction from the central portion, but bubbles may be formed at locations where the speed of spread is different, and the air bubbles may remain in the common ink chamber 84, the ink flow path, or the like. For example, a bubble is located in the throttle passage,
The flow of the ink from the common ink chamber 81 to the ink flow path is hindered, and the ink is not sufficiently injected into the ink flow path, or the bubbles are located in the ink flow path, and the ink is ejected even when the piezoelectric element is operated. However, there is a problem in that sufficient pressure is not applied to the ink, and the ink is not ejected from some of the plurality of nozzles, thereby deteriorating the printing performance. In addition, if the volume of the bubble expands due to a change in temperature, ink leakage may occur due to noise. Even if the introduction of air bubbles can be prevented, if the common ink chamber 84 has a large area, the area of the joint between the back plate 13 and the intermediate plate becomes small, and there is a possibility that sufficient sealing performance may not be secured.

The present invention has been made in view of such conventional problems, and has as its object to improve the printing performance by preventing bubbles from remaining in the ink passage inside the head.

[0005]

In the present invention SUMMARY OF to the To achieve such a problem, on one surface of the substrate, and an ink inlet for receiving a supply of ink from the outside, one end of the
It has multiple ink chambers communicating with the ink inlet,
The other side of the substrate is squeezed through each of the ink chambers.
Pressure generating means connected to the nozzle and communicating with the nozzle.
Having a plurality of ink channels pressurized by the step
Was.

[0006]

[0007]

[0008]

[Function] Supply ink from outside to both sides of the substrate
Receiving ink inlet, and one end communicates with the ink inlet
The ink chamber communicates with the
The ink flow paths to be pressed are formed in a vertical relationship.
While reducing the area had, at the time of injection of ink, the ink supplied from the ink inlet is due to bubbles Mase flow into the throttle passage, an ink flow path uniformly through the individual ink chambers
It is possible to prevent a decrease in print quality.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In the description of each embodiment, the same portions are denoted by the same reference numerals, and redundant description will be omitted. FIG. 2 shows an ink jet head according to a first embodiment of the present invention. This ink jet head has a nozzle plate 1, an intermediate plate 2, and a back plate 3 which are sequentially laminated and fixed.

As shown in FIG. 4, a nozzle plate 1 and an intermediate plate 2
A plurality of ink flow paths 4 arranged in the radial direction are defined between them. A nozzle 5 that penetrates the nozzle plate 1 in the thickness direction communicates with one end 4a, which is the center end of each ink flow path 4. In addition, each ink flow path 4
The other end portion 4b, which is the outer end portion, communicates with a throttle passage 6 that penetrates the intermediate plate 2 in the thickness direction. On the outer surface of the nozzle plate 1, the same number of piezoelectric elements 7 as the ink flow paths are fixed at positions corresponding to the respective ink flow paths 4.

As shown in FIGS. 1 to 3, an ink inlet 3a for receiving ink from an ink cartridge (not shown) is formed at the center of the back plate 3. As shown in FIGS. Intermediate plate 2
Between the ink inlet 3a and each throttle passage 6
Are formed, and a plurality of groove-shaped ink chambers 8 for guiding ink from the ink inlet port 3a to the respective throttle passages 6 are radially defined. Each groove-shaped ink chamber 8 is provided one for each throttle passage 6 (see FIG. 1).

Next, the operation of the first embodiment having the above configuration will be described. When the ink is injected into the ink jet head, an ink inlet 3
Since the ink supplied through a is guided to each throttle passage 6 by each groove-shaped ink chamber 8, the ink flows uniformly from the ink inlet 3 a toward each throttle passage 6. Further, the ink is injected to each nozzle 5 through each of the throttle passages 6 and each of the ink flow paths 4, whereby the entire inside of the head is filled with the ink.

As described above, according to the first embodiment, at the time of injecting ink, the ink supplied from the ink inlet 3a is guided to each throttle passage 6 by each groove-shaped ink chamber 8, so that the ink is The ink flows uniformly in each groove-shaped ink chamber from the ink inlet 3a toward each of the throttle passages 6. Therefore, air bubbles are prevented from remaining in each groove-shaped ink chamber 8 communicating the ink inlet 3a and each of the throttle passages 6, thereby improving printing performance.

Further, according to the first embodiment, since the wall 3b of the back plate 3 that partitions each groove-shaped ink chamber 8 extends near the ink inlet 3a, the intermediate plate 2 and the back plate 3 are joined. A large area can be ensured, whereby both plates 2 and 3 can be secured.
And the sealing strength between the two plates can be ensured greatly.

FIG. 5 shows a back plate 9 used in an ink jet head according to a second embodiment of the present invention. The back plate 9 of the second embodiment has a groove-shaped ink chamber 80 provided for each of the two throttle passages 6. Other configurations are the same as those of the first embodiment. That is, as shown in FIG. 5, each groove-shaped ink chamber 80 is provided with an ink inlet 9a.
An outer peripheral passage portion 80a having a length communicating with the two throttle passages 6 so as to guide the ink from the two throttle passages 6 to the two adjacent throttle passages 6 is provided. The outer peripheral passage portion 80a extends from one of the two adjacent throttle passages 6 to the other.

According to the second embodiment, a larger joint area between the intermediate plate 2 and the back plate 9 can be ensured by the reduced number of grooved ink chambers than in the first embodiment. As a result, the bonding strength between the two plates 2 and 9 can be further increased, so that a greater seal between the two plates can be ensured.

FIG. 6 shows a back plate 10 used in an ink jet head according to a third embodiment of the present invention. The third embodiment is an application of the second embodiment. Each of the groove-shaped ink chambers 81 has a length communicating with the two throttle passages 6 so as to guide the ink from the ink inlet 10a to two adjacent throttle passages 6, as in the second embodiment. The outer peripheral passage 81a is provided. This outer peripheral side passage portion 81
“a” extends to both sides from an intermediate portion of two adjacent throttle passages 6. According to the third embodiment, as in the second embodiment, the bonding strength between the intermediate plate 2 and the back plate 10 can be further increased, and the sealing performance between the two plates can be further ensured. . Further, it is possible to uniformly supply ink to a pair of throttle passages 6 communicating with one ink chamber 81.

FIG. 7 shows a back plate 11 used in an ink jet head according to a fourth embodiment of the present invention. In the ink jet head of the fourth embodiment, one groove-shaped ink chamber is provided for all the throttle paths. Other configurations are the same as those of the first embodiment. That is, as shown in FIG. 7, one groove-shaped ink chamber 82 has an outer circumferential side having a length communicating with all the throttle paths 6 so as to guide the ink from the ink inlet 11 a to all the throttle paths 6. It has a passage 82a.

According to the fourth embodiment, the joint area between the intermediate plate 2 and the back plate 11 can be further secured as much as the number of grooved ink chambers is smaller than in each of the above embodiments. As a result, the bonding strength between the two plates 2 and 11 can be further increased, and the sealing performance between the two plates can be further ensured.

FIG. 8 shows an ink jet head according to a fifth embodiment of the present invention. The back plate 12 of the fifth embodiment
Are applied examples of the first to third embodiments. That is, in this embodiment, each groove-shaped ink chamber 83 is formed such that the cross-sectional area gradually decreases as approaching the throttle passage 6.

According to the fifth embodiment, since the groove-shaped ink chamber 83 gradually decreases in cross-sectional area as it approaches the throttle passage 6, ink flows from the ink inlet 3a toward each throttle passage 6 toward the throttle passage 6. The flow velocity flowing in the grooved ink chamber 83 gradually increases. Therefore, bubbles are further prevented from remaining in each groove-shaped ink chamber 83, thereby improving printing performance.

[0022]

As described above, according to the present invention, the ink supplied from the ink inlet is guided to the throttle passage via the respective ink chambers, thereby preventing bubbles from remaining in the ink passage. Ink that can improve printing performance
The jet head can be configured with the smallest possible area
it can.

[Brief description of the drawings]

FIG. 1 is a view showing a back plate of an inkjet head according to a first embodiment of the present invention, and is a view taken along the line AA of FIG. 2;

FIG. 2 is a cross-sectional view of the entire inkjet head of the first embodiment, taken along line BB in FIG.

FIG. 3 is a cross-sectional view along the line BC in FIG. 1;

FIG. 4 is a plan view of the inkjet head according to the first embodiment.

FIG. 5 is a view showing a back plate of an inkjet head according to a second embodiment of the present invention.

FIG. 6 is a view showing a back plate of an inkjet head according to a third embodiment of the present invention.

FIG. 7 is a view showing a back plate of an inkjet head according to a fourth embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating an inkjet head according to a fifth embodiment of the present invention.

FIG. 9 is a view showing a conventional example, and is a plan view of a back plate forming a common ink chamber.

FIG. 10 is a sectional view of the back plate shown in FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle board 2 Intermediate board 3, 9, 10, 11, 12 Back board 4 Ink channel 4a One end 4b Other end 8, 80, 81, 82, 83 Groove-shaped ink chamber

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-148936 (JP, A) JP-A-2-266952 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/045

Claims (2)

(57) [Claims] An ink inlet for receiving supply of ink from the outside and a plurality of ink chambers having one end communicating with the ink inlet are provided on one surface side of the substrate, and on the other surface of the substrate, An ink jet head having a plurality of ink flow paths connected to each of the ink chambers via a throttle passage and communicated with a nozzle and pressurized by a pressure generating means. 2. The ink jet head according to claim 1, wherein the ink chamber is formed so that a side of the throttle passage is tapered.