JPH02286246A - inkjet head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording apparatus such as a printer that forms an ink image on a medium such as a recording paper by flying ink droplets, and more particularly to an inkjet printer head.

[Conventional technology]

A piezoelectric transducer consisting of a nozzle forming substrate having a plurality of nozzles, a pressure generating member arranged one-to-one facing each nozzle, and a gap between the piezoelectric transducer and the nozzle forming substrate and a gap between the piezoelectric transducer and the nozzle forming substrate. Japanese Patent Publication No. 8953/1983 discloses an on-demand inkjet head that includes ink that fills the periphery of the head and that displaces a piezoelectric transducer using an applied voltage to eject ink from a nozzle. An inkjet head with this structure has high ink ejection efficiency and ejection stability because the piezoelectric transducer is displaced almost perpendicularly to the nozzle forming substrate and the ink flow path of the nozzle meniscus is short. It has the advantage that even if foreign matter such as air bubbles or dust gets mixed in, normal operation is possible without being affected by this. Furthermore, since the pressure generating member has a cantilevered or double-sided beam structure, the electromechanical conversion efficiency is high and the required pressure generating member displacement can be obtained with a low voltage.

[Problem to be solved by the invention]

However, in the above-mentioned conventional technology, the shape of the nozzle is a parallel hole, a tapered hole, or a horn hole, but the minimum diameter of the nozzle is 1.
It is small, less than 00 μm. Therefore, it is difficult to process this nozzle by drilling or other methods, and techniques such as electroforming have been used. Therefore, it is difficult to reduce the distance between adjacent nozzles to a certain value or less, which prevents high dot density printing. Therefore, the present invention is intended to solve these problems.
The purpose is to provide an inkjet head with a high dot density in which the print dot density is not restricted by the nozzle.

[Means to solve the problem]

An inkjet head of the present invention includes a nozzle forming substrate having a nozzle, and a plurality of pressure generating members disposed opposite to the nozzles and immersed in ink, and displacing the pressure generating members by an applied voltage. In the inkjet head that increases the pressure of ink present in a gap with the nozzle forming substrate and ejects it from the nozzle, a plurality of the pressure generating members share one hole as the nozzle.

[Effect]

According to the effect of the present invention, since the plurality of pressure generating members share one hole as the nozzle, the mounting intervals of the plurality of pressure generating members are not affected by the shape of the nozzle, and the pressure generating members The interval between the two can be reduced.

Therefore, when printing, the distance between adjacent ink droplets ejected from each of the pressure generating members becomes shorter, and the density of printed dots increases.

〔Example〕

The details of the present invention will be explained below using examples with reference to the drawings.

FIG. 1 is a perspective view of a printer equipped with an inkjet head according to the present invention, in which a recording medium 1 is wound around a platen 4 by pressure from feed rollers 2 and 3, and is conveyed in the direction of an arrow 5 as recording progresses. Ru. Guide shaft 6.7
An inkjet head 9 having a plurality of nozzles is mounted on a carriage 8 that is guided by a carriage 8 and movable in a direction parallel to the axis of the platen 4, and as it moves in the direction of an arrow 10, ink droplets are ejected from each nozzle. The ink is ejected to form an ink image on a recording medium.

FIG. 2 is a sectional view of an inkjet head showing an embodiment of the present invention. Nozzle 1 arranged on nozzle forming substrate 15
The tips of the plurality of pressure generating members 13 are attached to the nozzle forming substrate 15 via spacers 17 so as to be arranged at positions corresponding to the pressure generating members 13 with a gap therebetween. Gap is 50
It is less than μm. The nozzle 14 is a parallel slit penetrating the nozzle forming substrate 15, and its width S is 100 μm or less. The pressure generating member 13 is made of a laminated material of a piezoelectric element 12 and a metal plate 11, and its length L is 5 mm or less, and its thickness t is 50 mm.
The width is 0 μm or less, and the width is 500 μm or less. A space surrounded by the nozzle forming substrate 15 and the casing 18 is filled with ink 19.

When the applied voltage 16 is selectively applied to the pressure generating member 13, the corresponding pressure generating member 13 is displaced in the direction of the arrow 22 and presses the ink, so that the ink below the pressure generating member 13 in the nozzle 14 is removed from the nozzle 14. It is ejected as droplets 20. At this time, since the ink inside the nozzle is held within the nozzle by surface tension, only the ink where the pressure under the pressure generating member 13 has become high is ejected, and ink from other parts is not ejected.

FIG. 3 is a cross-sectional view taken along line A-A in FIG. In this embodiment, the nozzle 14 has a slit shape passing through the nozzle forming substrate 15, and a plurality of pressure generating members 13 are arranged along the slit-shaped nozzle 14, so that the interval d between the pressure generating members 13 is It can be made smaller without being affected by the shape of the nozzle 14. When the width of the pressure generating members 13 is 250 μm, the interval d between the pressure generating members 13 can be set to about 300 μm, and the dot density of printing is 80 dpi (dpi
(represents the number of dots per inch length), which is an improvement of about 30% compared to the conventional 60 dpi.

FIG. 4 is a sectional view of an inkjet head showing an embodiment of the present invention. The cross section is similar to the cross section AA shown in FIG. In FIG. 4, components common to those in FIG. 2 are given the same numbering.

However, in this embodiment, the shape of the pressure generating member 13 is trapezoidal, and the narrow portion thereof faces the nozzle 14, and is arranged so as to surround the nozzle 14 from opposite directions alternately.

Thereby, the distance d between the pressure generating members 13 can be further reduced. Further, by arranging the pressure generating members 13 alternately, the intervals between the base portions of the pressure generating members 13 are widened, which is advantageous in terms of manufacturing.

〔Effect of the invention〕

In the inkjet head of the present invention, as described above, since the plurality of pressure generating members share one hole as a nozzle, the mounting distance of the plurality of pressure generating members is not affected by the nozzle shape. Therefore, the distance between the pressure generating members can be reduced, and the distance between adjacent ink droplets ejected from each pressure generating member is shortened. Therefore, when these ink droplets are printed on paper or the like, there is an effect of increasing the dot density of the print.

In addition, when a configuration is configured in which multiple pressure generating members are disposed to eject multiple ink droplets at the same time, there is no need to dispose multiple nozzle holes on the nozzle forming substrate, and only one hole passing through the nozzle forming substrate is required. It only needs to be installed, making manufacturing easier and reducing costs.

In this example, the nozzle shape is a parallel slit, but this does not impose any restrictions on the nozzle shape; any hole penetrating a nozzle forming substrate that is shared by multiple pressure generating members may be used. It is clear from the gist of the invention that the shape may be like this.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a printer equipped with an inkjet head showing an embodiment of the present invention. FIG. 2, FIG. 3, and FIG. 4 are cross-sectional views of an inkjet head according to the present invention. 1 Recording medium 9 Inkjet head 11 Metal plate 12 Piezoelectric element 13 Pressure generating member 14 Nozzle 15 Nozzle forming substrate 17 Spacer 19 Ink applied voltage casing 1 Figure 73: Toko Rikiya SE L Gun Saisai Figure 3

Claims (1)

[Claims] A nozzle forming substrate having a nozzle, and a plurality of pressure generating members disposed opposite to the nozzle and immersed in ink, the pressure generating members are displaced by an applied voltage, and the pressure generating members are displaced by an applied voltage, and the nozzle forming substrate An inkjet head that increases the pressure of ink existing in a gap and causes the ink to be ejected from the nozzle, wherein a plurality of the pressure generating members share one hole as the nozzle.