JPH03297651A - Ink jet head - Google Patents

Abstract

PURPOSE:To make deburring operation or the like to be generated in injection moulding of a substrate or the like unnecessary by enabling a bubble to be discharged easily by a method wherein a hole diameter on an ink discharge opening side of a nozzle to be formed to a nozzle plate is formed small, and a hole diameter interconnected to a passage is formed larger than a diameter of the passage. CONSTITUTION:A nozzle 7 is formed so that a hole diameter on its ink discharge opening 7a side becomes small and a hole diameter on a side 7b interconnected to a passage 3 becomes large. Then, in a part interconnected to the passage 3, a diameter on an interconnecting side 7b of the nozzle 7 is so constructed as to become larger than a diameter 3a of the passage 3. For instance, the diameter 3a of the passage 3 is taken as phi0.2mm, a diameter on the interconnecting side 7b of the nozzle 7 is taken as phi0.3mm, and a diameter of the ink discharge opening 7a is taken as phi0.05mm. Such a parabolic nozzle form can be manufactured easily by nickel electrocasting. Such the nozzle form can be manufactured by either press working or injection moulding. By this structure, remaining of bubbles disappears and further discharging of the bubbles becomes easy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of an inkjet head suitable for an inkjet recording apparatus that performs recording by ejecting droplets.

[Prior Art] Regarding a head in which a pressure generating section is connected to a nozzle for discharging ink droplets, the details of the connection section between the ink flow path and the nozzle are as shown in FIG. 7, for example. In the figure, 20 is a pressure generating section or a flow path communicating with the pressure generating section, 21 is a nozzle plate, and 2
3 is a nozzle formed on the nozzle plate 21.

[Problems to be Solved by the Invention] However, in such a conventional structure, bubbles 22 tend to remain in the flow path 20 as shown in FIG. Because it is pressed by
There was a problem that it could not be easily discharged.

Furthermore, when the pressure generating part and the flow path 20 are made by injection molding, press working, drilling, etc., burrs are formed at the outlet of the flow path 20, and when joining the nozzle plate 21, the burr must be removed in advance. This operation was extremely difficult and a major problem in mass production.

[Means for Solving the Problems] Therefore, in order to solve the above problems, the present invention reduces the diameter of the hole on the ink ejection port side of the nozzle formed in the nozzle plate, and reduces the diameter of the hole communicating with the flow path. Thicker than the road diameter (formed).

[Example J] Examples of the present invention will be described in detail below. FIG. 1 is a plan view of an embodiment of an inkjet head according to the present invention, and FIG. 2 is a sectional view taken along line A-A in FIG. In FIG. 1, the diaphragm 8 shown in FIG. 2 is omitted.

Reference numeral 1 denotes a substrate made of a plastic material, on one side of which a series of ink supply channels, such as a pressure chamber 2, a flow path 3, and an ink chamber 5, are made by injection molding. One end of the pressure chamber 2 communicates with the ink chamber 5 with a constriction section 6 in between. Further, the other end of the pressure chamber 2 communicates with a nozzle 7 formed on a nozzle plate 4 via a flow path 3 in a direction perpendicular to the substrate 1. 8 is a thin diaphragm, which is connected to one side of the substrate 1.

Ink enters 12 portions of the ink chamber 5 from the front side of FIG. 1 in a direction perpendicular to the substrate 1 through a supply vibrator (not shown). The entered ink spreads inside the ink chamber 5,
Next, each pressure chamber 2, flow path 3, and nozzle 7 are filled. A filling means such as a pump is used to fill the ink.

FIG. 3 is a diagram showing a communication portion between the nozzle 7 formed on the nozzle plate 4 and the flow path 3 formed on the substrate 1. As shown in FIG. Note that 9 is an adhesive layer.

The nozzle 7 is formed so that the hole diameter on the side of the ink discharge lower a is small and the hole diameter on the side 7b communicating with the flow path 3 is large. At the communicating part with the flow path 3, the diameter of the flow path 3 is 3.
The diameter of the communication side 7b of the nozzle 7 is larger than that of the nozzle 7a. For example, the diameter 3a of the flow path 3 is φ0.2 mm.
, the diameter of the communicating side 7b of the nozzle 7 is 0.3 mm, and the diameter of the ink discharge lower a is 0.05 mm.

Such a parabolic nozzle shape can be easily made by nickel electroforming.

FIG. 4 shows another example of the nozzle shape. Such a nozzle shape can be formed by press working or injection molding.

According to the above-described structure, there are no remaining bubbles, and bubbles can be easily discharged. Figure 5 shows the suction cap lO on the nozzle plate 4.
This shows the pattern when the air bubbles in the pressure chamber 2 and the flow path 3 are discharged by pressing against it and suctioning it with the suction pump.
Unlike the conventional example shown in Fig. 7, it is possible to stop the flow of bubbles.
Since there is no step that could be considered an obstacle, bubbles can be easily discharged.

Figure 6 shows a substrate 1 made by plastic injection molding,
A nozzle 7 connected to this is shown. With respect to the paris 11 that occurs at the outlet of the flow path 3, by adopting the structure of this embodiment, the paris 11 can be escaped, and it is almost impossible to join the nozzle plate 4 to the 6. Assembling is possible without the need to remove particles, which has a great effect on mass production.

As is clear from the above description, the same effects as in the above-described embodiments can be obtained even if the cross-sectional shape of the flow path 3 and the hole shape of the nozzle 7 are not only circular but also rectangular.

[Effects of the Invention] As explained above, according to the inkjet head according to the present invention, air bubbles can be easily discharged even in a structure in which a substrate and a nozzle plate are joined.

In addition, the nozzle plate can be joined without performing deburr removal work to eliminate deburrs generated during injection molding of substrates, etc., which is extremely effective in mass production assembly.

Furthermore, regarding the bonding accuracy between the substrate and the nozzle plate, even if there is a mutual positional misalignment, the hole diameter on the nozzle side is made large so that the misalignment can be absorbed and the flow can be adjusted so as not to affect the ejection of ink droplets. It became possible to communicate the passage and the nozzle.

[Brief explanation of the drawing]

1 and 2 are diagrams showing an embodiment of an inkjet head according to the present invention, in which FIG. 1 is a plan view and FIG. 2 is a sectional view taken along the line A-A in FIG. FIGS. 3, 4, 5, and 6 are sectional views showing embodiments of an inkjet head according to the present invention, and FIG. 7 is a sectional view showing an example of a conventional inkjet head. 1 ・ 2 ・ 3 ・ 4 ・ 5 ・ 7 ・ 9 ・ 10 ・ 1 l ・ 13 ・ ・Substrate, pressure chamber, channel, nozzle plate, ink chamber, nozzle, adhesive layer, suction cap, Paris, piezoelectric element

Claims (1)

[Claims] In an inkjet head in which a substrate on which an ink flow path is formed and a nozzle plate having a nozzle that communicates with the flow path are joined, the hole diameter on the ink ejection port side of the nozzle is formed to be small, and the diameter of the hole on the ink ejection port side of the nozzle is formed to be small. An inkjet head characterized in that a hole diameter on a communication side is formed larger than a diameter of the flow path.