JPS61215059A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To automatically remove the clogging of an ink nozzle, by providing the ink nozzle in a pressure generator consisting of a piezoelectric element and a vibration plate. CONSTITUTION:When the ink emitting nozzle 11 provided in a pressure generator 10 is clogged with coagulated ink or dust, said pressure generator 10 is subjected to forcible vibration 9 and coagulated ink or dust 7 is forcibly destructed or released from the nozzle 11 by the pressure 8 generated in an ink chamber 5 and the mechanical minute deformation of the nozzle part by the deformation of the pressure generator 10 to be emitted to the outside of the ink chamber 5 along with ink. With respect to stronger clogging, the pressure generator is vibrated more forcibly at the mechanical resonance point of the pressure generator 10 and the ink chamber 5 and the max. nozzle deformation and the pressure from the ink are obtained to enable the elmination of ink clogging. Both of processes are performed prior to printing and a stable image can be always obtained in printing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pressure pulse type inkjet recording apparatus.

[Technical background of the invention and its problems]

Inkjet recording methods that can record on plain paper include electrostatic acceleration, pressure pulse, and pressure vibration methods, and more recently, a bubble jet method has been developed. All of these inkjet recording methods are superior to other recording techniques in terms of printing speed, device simplicity, ease of color printing, and color reproducibility. However, despite these advantages, few inkjet systems have been commercialized due to instability of ink flight due to ink clogging and poor maintenance.

Among these inkjet recording methods, the pressure pulse method has been most well researched and commercialized for use in office equipment, although it has drawbacks such as the simplicity of the device.

Next, problems with the conventional pressure pulse type inkjet device will be described using FIGS. 2 and 3. FIG. 2-(,) is a general cross-sectional schematic diagram of a pressure pulse type inkjet head. The head body (2D) consists of an ink inlet (23), an ink chamber (c), and a pressure generator (to).

The head main body C1,) is provided with an ink ejection nozzle. Further, the pressure generating device (7) is composed of a metal bridge board (foundation) and a piezoelectric element (c). FIG. 3 shows one cycle up to ink ejection by this head. Figure 3-(
A) is a steady state in which ink has reached the nozzle tip 67), and at this time a signal voltage is applied to the pressure generator [CII]. This applied signal voltage causes the pressure generator to deform as shown in Figure 3-(b).

Pressure is created in the ink chamber (5). As a result, ink is ejected from nozzle 01 as shown in (36). When the signal voltage is turned off, the pressure generator (
The fourth corner returns to its original state, and ink particles (36) are generated and fly. At this time, the ink in the nozzle is drawn into the back of the nozzle (391).
), the ink moves to the nozzle tip due to the wetting of the ink and the nozzle and the surface tension of the ink, and returns to its original state. FIG. 2-(b) shows a case in which clogging occurs in such a conventional inkjet head due to long-term storage or dust. Clogging occurs in the nozzle (c) due to coagulation of the ink due to long-term standing, or due to dirt in the ink. At this time,
Although the pressure Q81 generated in the ink chamber from the forced pressure generating device for clogging removal may eliminate the clogging, this pressure alone is generally not sufficient to eliminate the clogging. As a result, printing becomes impossible.

[Purpose of the invention]

An object of the present invention is to provide an inkjet recording apparatus that can automatically remove clogging of nozzles.

[Summary of the invention]

The inkjet recording device according to the present invention includes a pressure pulse type inkjet ink nozzle in a pressure generating device consisting of a piezoelectric element and a diaphragm, and applies mechanical vibration to the nozzle at the same time as ink is ejected to prevent clogging of the nozzle. Even if ink clogging occurs due to long-term use of an inkjet recording device, mechanical vibrations are forcibly applied to the ink nozzles to destroy and remove the solidified ink and dirt that are the cause of the clogging.

[Embodiments of the invention]

Next, it will be explained in detail using figures. FIG. 1-(,) is a schematic cross-sectional view of a pressure cavus type inkjet head of the present invention. The head body (1) consists of an ink inlet (2), an ink chamber (5), and a pressure generating device (1 (It). This pressure generating device consists of a metal plate (4) and a piezoelectric element (3). , the ink ejection nozzle I exists at the point of maximum amplitude of this vibration.The pattern of ink ejection by this inkjet head is schematically shown in Figure 4.The principle of ink ejection is the same as that of the conventional pressure pulse type inkjet. 4-(a) shows a steady state in which no signal voltage is applied to the pressure generator (50).

Ink from the ink inlet (44) is externally coupled to an ink supply tank. The ink that enters from this ink inlet fills the ink chamber (49) of the inkjet head. At the nozzle (54), the negative hydrostatic pressure applied to the ink and the surface tension of the ink at the nozzle are balanced. When a signal voltage is applied to the pressure generator (50), the pressure generator (50) deforms as shown in (51) in FIG. 4(b).

As a result, the volume of the ink chamber (451) decreases, and the pressure generated by the pressure generator causes the nozzle diameter (50 to 60μφ
) is ejected from the nozzle. At this time, the volume reduction amount of the ink chamber is the ejected ink (55)
i is equal to the total volume of ink escaping from the ink inlet. During this printing, the maximum displacement amount at the nozzle portion of the pressure generating device 6Q is several microns at most. Next, Figure 4 (
When the signal voltage is turned off as shown in C), the deformation of the pressure generator returns to its initial state. At this time, ink particles (56
) occurs and flies. As a result, the ink in the head returns to its initial state as shown in FIG. 4(d).

〔Effect of the invention〕

Next, the effect when the inkjet head of the present invention is left unused for a long time and clogging occurs due to ink solidification or dust in the ink will be explained with reference to FIG. 1(b). A nozzle (L) provided in the pressure generator (10)
2 is clogged with ink coagulation or dust, this pressure generating device is forced to vibrate (9) to reduce the pressure generated in the ink chamber (8) and the mechanical pressure caused by the deformation of the pressure generating device in the nozzle. With slight deformation, ink coagulation or dust is forcibly destroyed or peeled off from the nozzle, and is ejected together with the ink to the outside of the ink chamber. In addition, for severe clogging, the pressure generator (5) is forcibly vibrated at the mechanical resonance point between the ink and the pressure generator to obtain the maximum amount of nozzle deformation and pressure from the ink. It is possible to eliminate clogging of ink.

All of these steps are performed before printing, and a stable image can always be obtained during printing.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an inkjet head according to an embodiment of the present invention, in which FIG. 1(a) is a sectional view of the head, FIG. The figure is a schematic diagram of a conventional pressure pulse type inkjet head, FIG. 3 is an explanatory diagram of ink discharge of a conventional pressure pulse type inkjet head, and FIG. 4 is an explanation of ink discharge of the present invention. 1: Ink head body 2: Ink inlet 10: Pressure generating device 11: Nozzle 7: Clogged ink coagulates or dust, etc. Agent Patent attorney Noriyoshi Chika (and 1 other person) Exhausted\sa64<p Praise for Ken ni candy 4g last time snoring - (a) (b) 8th (a) (b) 4th (C) (d) Figure (C) (d) Figure

Claims (1)

[Claims] In a pressure pulse type ink jet recording device having an ink chamber having an ink suction port and a pressure generating element device in contact with the ink chamber and comprising a piezoelectric element and a diaphragm, an ink nozzle is provided in the pressure generating element. An inkjet recording device featuring: