JPS608074A - Nozzle for ink jet type printer - Google Patents

Abstract

PURPOSE:To obtain a nozzle capable of stably jetting ink droplets by using a system in which the propagation of higher order acoustic waves originated from resonance unnecessary for the jetting of ink droplets in an ink communication path leading an ink droplets jet orifice with a pressure chamber is controlled. CONSTITUTION:An acoustic filter in which cross sections S1, S2 and S3 of an ink communication path 71 leading a pressure chamber 61 with an orifice 41 are varied by lengths l1, l2 and l3 is made up. Inductive acoustic reactance L in the equivalent circuit corresponds with the portion of the cross section S1, and capacitive acoustic reactances C1 and C2 correspond with the portions of cross sections S2 and S3, which is represented by L=rhol1/S1, C1=l2S2/rho.v<2>, and C2=l3 S3/rho.v<2>, where rho is density of ink and (v) is sound speed in ink liquid. The length and cross section of the ink communication path are set up such that the cut-off frequency, f=1/2pi[L(C1+C2)]<1/2>, of the acoustic filter becomes lower than the frequency of sound wave to be generated by the resonance of the pressure chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a nozzle for an inkjet printer;
In particular, the present invention relates to nozzles in the Innoculus on Demand system.

Technology background Inkjet printers are extremely low noise.
It is widely used because it allows high-speed printing, can use plain paper, does not require developing and fixing, and has flexibility in recording. There are various types of inkjet printers, especially InA? Luz on
Unlike other methods, the demand method does not require the drawing required for deflection or the equipment required for ink processing, so it has a simple structure and is often used in small devices. However, there are various unstable factors that affect print quality, such as air bubbles in the ink liquid and groups of minute ink droplets after being ejected, and improvements are desired.

Prior Art and Problems FIG. 1 is a cross-sectional view of the basic structure of a nozzle in a conventional in- or Lux-on-demand system.

An ink supply port 2 is provided in the nozzle 1, and ink is supplied from an ink reservoir through an ink supply path.

A piezoelectric element 3 made of a piezo crystal or the like is provided on the outer wall of the nozzle 1, and when a lucid signal voltage is applied to the piezoelectric element 3, a volume deformation occurs in the piezoelectric element 3. Pressure waves (sound waves) are generated in the pressure chamber 6, and ink in the ink chamber 5 is ejected from the orifice 4 to print on recording paper. The shape of the ink chamber 5 consists of a pressure chamber 6 that generates sound waves by the volumetric deformation of the piezoelectric element 30, and an ink communication path 7 between the pressure chamber 6 and the orifice 4. In such a structure, all of the sound waves generated by the volume deformation of the piezoelectric element 3 due to the 9-lust signal voltage from the arm power source O8C and the resonance generated by the reflection of this sound wave at the orifice 4 are eliminated. Ink droplets are ejected using high-order sound waves. However, in addition to the jetting of ink droplets by the sound waves necessary for printing, subsequent jetting of satellite particles of ink droplets by high-order sound waves due to resonance that is unnecessary for printing occurs, resulting in poor print quality such as stains on the recording paper. There was a problem that the value decreased.

OBJECTS OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to suppress the propagation of high-order sound waves due to unnecessary resonance for ejecting ink droplets in an ink communication path that communicates an ink droplet ejection orifice and a pressure chamber. An object of the present invention is to provide a nozzle that can stably eject ink droplets.

DESCRIPTION OF THE INVENTION According to the invention, the object is to provide a nozzle in an impulse-on-demand system for an inkjet printer, which includes an ink droplet ejection orifice, and a full pressure is applied to the ink in order to cause the ink droplet to be ejected from the orifice. A pressure chamber, an electromechanical transducer that generates pressure in the pressure chamber, and an ink communication path that communicates the orifice with the pressure chamber, which is formed by changing its cross-sectional area by an arbitrary length. This is accomplished by providing an inkjet printer nozzle having a sound+IP waveform consisting of inductive and capacitive acoustic reactances.

Embodiment FIG. 2 ( ) is a sectional view of a nozzle as an embodiment of the present invention. In FIG. 2(,), the nozzle 11 according to the present invention is constituted by an ink chamber 51 consisting of an ink supply port 21, a piezoelectric element 31, an orifice 41, a pressure chamber 61, and an ink communication passage 71. In such a configuration, the ink communication path 71 has cross-sectional areas S, lS, and Ss as shown in the figure, and a length tlst! and L3, thereby constituting a p-acoustic wave transducer (t-), whose equivalent circuit is shown in FIG. 2(b). This equivalent circuit is based on acoustic engineering, and if the end of an acoustic tube with a diameter and length sufficiently small compared to the wavelength of the sound wave is closed, the tube will act as a capacitance in an electric circuit. It is based on the property that it acts like an inductance when the ends are open. Therefore, in Fig. 2(b), the inductive acoustic reactance L is located at the cross-sectional area S, and the capacitive acoustic reactance C1 is located at the cross-sectional area S.
It corresponds to the s part. Here, if the ink density is ρ and the sound velocity in the ink is V, then it is given by L=ρ·tt/5I C1-42·S2/ρ·v2 Cz =ls·Ss/ρ·v2. The cutoff frequency f of the acoustic wave transducer is given by /=1/2π〆τ t Frollo2], so the ink communication passage should be set so that the cutoff frequency f is lower than the frequency of the sound waves generated by the resonance of the pressure chamber. Set the length and cross-sectional area.

As a result, it is possible to absorb and attenuate the sound waves often generated due to resonance in the pressure chamber, which has a particularly bad effect on ink ejection, and to perform stable ink droplet ejection without forming atomized ink droplet groups.

Effects of the Invention According to the present invention, it is possible to prevent unnecessary sound waves from reaching the orifice for ejecting ink droplets, resulting in more stable ink droplet ejection without the generation of atomized ink drop groups or satellite particles. I can do it.

[Brief explanation of drawings]

FIG. 1(a) is a sectional view showing the structure of a conventional nozzle, FIG. 1(b) is a sectional view taken along line A-A' in FIG. 1(a), and FIG. The A-A' sectional view showing the structure of the nozzle as an example, and FIG.
This is an acoustic engineering equivalent circuit of the ink communication path shown in Figures (,). (Explanation of symbols) 1.11... Nozzle, 2.21... Ink supply port,
3.31... Piezoelectric element, 4.41... Orifice,
5゜51... Ink chamber, 6.61... Pressure chamber, 7,
71... Ink communication path. Patent applicant Fujitsu Ltd. Patent agent Akira Ikugi Patent attorney Kazuyuki Nishidate 1) Yukio Patent attorney Akira Yamaguchi (7)

Claims (1)

[Claims] 1. An impulse-on-demand nozzle for an inkjet printer includes an ink droplet ejection orifice, a pressure chamber that applies pressure to the ink in order to eject the ink droplets from the orifice, and a pressure chamber that generates pressure in the pressure chamber. Acoustics consisting of an electro-mechanical transducer, and an ink communication path that communicates the orifice with the pressure chamber, which is formed by changing the cross-sectional area of the ink passage by an arbitrary length, and consists of inductive and capacitive acoustic reactances. p
1. A nozzle for an inkjet printer, comprising: a corrugated nozzle.