JPS59162060A - Ink-jet recording-head - Google Patents

Abstract

PURPOSE:To prevent generation of satellite grains or ink fine particle group and contrive a higher quality of recording, by installing a sound-filter of resonance type filtering pressure waves generated in ink pressurized in a pressure chamber. CONSTITUTION:When a electric voltage in a pulse form is applied to a piezo- electric element 3, a deformation due to electrostrictive effect is invited and by this deformation, side walls of a ink-chamber 2 contacting with the piezo-electric element 3 is deformed to cut an inside capacity of the ink-chamber 2 and ink contained inside the ink-chamber 2 is pressurized. Even after application of pulse voltage to the piezo-electric element 3 and restoration to the original shape of said side walls of ink-chamber 2, a damping pressure fluctuation of pressure is continued for a short period of time on ink contained inside the ink-chamber because of resonance, etc. of side walls of the ink-chamber 2. On the other hand, by installing a resonance-type sound move filter 6, a frequency element, among said damping pressure fluctuation, causing satellite grains or atomized ink particle group is prevented from transmission to a nozzle 5 through a passage 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a drop-on, drop-on-demand type inkjet recording head, and particularly to an inkjet recording head that can improve recording quality.

Prior Art and Problems Dropping, on-demand type inkjet recording, by pressurizing the ink in the pressure chamber in a nozzle shape as needed, ejects an ink sludge from the nozzle, and In such an inkjet recording head, when the ink is pressurized, the pressure in the ink chamber increases due to parasitic vibration of the side wall of the ink chamber due to the pressurization. 1. Not only does this change in a pulse-like manner, but it is followed by discrete fluctuations in attenuation, and for this reason, in addition to the ink droplets corresponding to the pulse-like changes in ink pressure, they are also called satellite particles. Following the ejection of the ink droplets, small-diameter ink droplets or atomized ink particles are generated, and these are one of the main causes of recording quality deterioration in drop-on-demand inkjet recording. It has become.

0 OBJECTS OF THE INVENTION An object of the present invention is to provide an inkjet recording head that can prevent the generation of the satellite particles or ink fine particle groups and improve recording quality.

(D) Structure of the Invention The inkjet recording head of the present invention includes a pressure chamber filled with ink and applying pressure to the ink, a nozzle that ejects the ink pressurized in the pressure chamber, and a nozzle that is pressurized in the pressure chamber. Pressed ink? In the drop-on-demand type inkjet recording head, a resonant acoustic filter is provided to filter the pressure waves generated in the pressurized ink in the pressure chamber, and the ink By preventing the attenuating pressure fluctuations generated in the chamber from reaching the nozzle, the generation of satellite particles or groups of fine ink particles is prevented, and recording quality is improved.

(G) Examples of the Invention The gist of the present invention will be specifically explained below with reference to illustrated examples.

FIG. 1 shows a side sectional view of the inkjet recording head according to the present invention, and FIG. 2 shows a sectional view taken along the line AA in FIG. In Figures 1 and 2, 1 is a supply port that supplies ink to a pressure chamber described later, 2 is a pressure chamber that is filled with ink and applies pressure to the ink, and 3 is provided on the outside of the wall forming the pressure chamber. a piezoelectric element that acts to give mechanical deformation to the side wall; 4 is a passageway that leads pressurized ink in the pressure chamber 2 to a nozzle described below; 5 is a nozzle that ejects the pressurized ink in the pressure chamber 2; 6 is one end (downward in Figure 2)
This is a resonant acoustic filter that is closed at one end and opened to the passage 4 side, and filters pressure waves generated in pressurized ink in the pressure chamber 2.

The resonance type acoustic filter 6 is a rectangular cylinder as shown in Fig. 3, and the depth is z+(myn), and the lengths of the sides of the opening on the passage 4 side are each 21 (mm) and t3 (mm). If the propagation speed of sound in the ink is U (m/8), then the resonant frequency f (1, H,) of the resonant acoustic filter 6 is 1. And when L3 is very small compared to tl, ? It is expressed as f=y; 1/(4Xt+>(i).

3- When a pulse voltage is applied to the piezoelectric element 3, 'l'lj'
A deformation occurs due to the curvature effect, and as a result of this deformation, the side wall of the ink chamber 2 at the portion in contact with the piezoelectric element 3 is deformed so as to reduce the internal volume of the ink chamber 2, and the ink inside the ink chamber 2 is pressurized.

Even after the application of the pulsed voltage to the piezoelectric element 3 ends and the deformation of the side wall of the ink chamber 2 is restored, damping pressure fluctuations occur in the ink inside the ink chamber 2 due to resonance of the side wall of the ink chamber 2. Lasts for a short time.

However, by designing the resonant acoustic filter 6 based on the above (1), the frequency component that causes the generation of the sanitary particles or the atomized ink particle group among the attenuating pressure fluctuations is transmitted to the passage 6. can be prevented from being transmitted to the nozzle 5 via the.

For example, when the frequency f of the frequency component is 404 Hz,
The value of t is selected to be 9.4 mm, and t2 is 1 to 2 mm5t*
By setting Q to 2 mm, this frequency component can be removed.

Beauty However, $=1500m/S.

4- By providing a plurality of resonant acoustic filters 6 in the passage, it is also possible to remove a plurality of frequency components from the attenuating pressure fluctuations.

Also, the depth of the 11-square acoustic filter 6 is 1. By making it possible to vary the resonant frequency f'f using a screw etc.
: Can also be made variable.

In the above embodiment, the resonant acoustic filter 6 is provided in the passage 4, but it can also be provided in the pressure chamber 2 or elsewhere.

(g) As described in detail, according to the present invention, it is possible to prevent satellite particles and atomized ink fine particle groups that are generated after ink droplets necessary for printing performance, thereby improving printing quality.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of an embodiment of the present invention, and FIG. 3 shows the shape of a resonant acoustic filter. 1 and 2, 2 is a pressure chamber, 4 is a passage, 5 is a nozzle, and 6 is a resonant acoustic filter. 4ya1. stomach. □ 7.7□M"1

Claims (2)

[Claims] (1) A pressure chamber filled with ink and applying pressure to the ink, a nozzle that ejects the ink pressurized in the pressure chamber, and a passage that guides the ink pressurized in the pressure chamber to the nozzle. A drop-on-demand type inkjet recording head comprising a resonant acoustic filter for filtering pressure waves generated in pressurized ink in the pressure chamber. (2) The inkjet record head according to claim 1, wherein the resonance type acoustic filter has one end closed and the other end open to the passage side.