JPS59214659A - Head for ink jet printer - Google Patents

Abstract

PURPOSE:To obtain an ink jet printer head capable of jetting ink at high speeds stably by using a system in which ink is subjected to an electrolysis and ink droplets are formed by bubbles of hydrogen and oxygen gases. CONSTITUTION:An aqueous ink 6 is fully packed to a nozzle port 7, a given voltage is applied between electrodes 2, gases 8 are formed on the surface of the electrodes 2 by electrolysis, and bubbles 9 of these gases 8 are grown to expose ink from the nozzle port 7. As the bubbles 9 grow, ink isolated on the nozzle port side is discharged from the nozzle port 7 in the form of a droplet. Since the inside diameter of the nozzle port is sufficiently small, the generation of bubbles and discharge of ink droplets are made instantaneously.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to an inkjet printer that aims to speed up and stabilize the ejection of ink droplets by forming ink droplets using air bubbles generated when water in ink is electrolyzed. related to heads.

[Prior art]

Based on the bubble jet method (as a conventional inkjet printer head, for example, the one shown in Figure 1)
A housing 13 includes an ink chamber 11 that introduces ink pumped by a pressure pump from one end and a nozzle 12 that discharges ink particles from the other end, and a nozzle provided around the nozzle 12. It is constructed with a heat generating section 14 that uses a laser or the like to heat the ink inside. The heat generating section 14 is connected to a power source section 15 that receives a supply of heat generating power, and the power source section 15 is connected to a control section 16 that performs control according to a print signal.

In the above configuration, when the control unit 16 controls the power supply unit 15 in accordance with the print signal to supply power to the heat generating unit 14 when ejecting ink droplets, the ink in the nozzle 12 instantaneously boils and generates bubbles. , ink particles 17 are generated and ejected by the bubbles. According to this drop-on-demand type inkjet printer head, the device can be simplified and control can be made easier compared to the electric field control type or charge control type.

However, according to the conventional inkjet printer head, since the ink in the nozzle is boiled at a high temperature by the heat generating section 14, there is a disadvantage that it is difficult to prepare a thermally stable ink.

[Object and structure of the invention]

The present invention has been made in view of the above, and in order to perform stable jetting at high speed, ink is electrolyzed and ink droplets are generated by hydrogen gas and oxygen gas bubbles generated at this time. The present invention provides a head for an inkjet printer having the following characteristics.

[Embodiments of the invention]

Hereinafter, the head for an inkjet printer according to the present invention will be explained in detail.

2, 3, and 4 show an embodiment of the present invention, which shows a pair of nozzle substrates 1 formed in a U-shape and an electrode provided at the tip of the nozzle substrate 1. 2 and electrode 2
and a metal film 3 having the function of a lead wire forming an electric circuit.
, a photosensitive resin 4 coated on the metal film 3, and a groove 5 in which the electrode 2 and the metal film 3 are laid,
Both difference plates 1 are integrated into one body using adhesive or the like, and ink 6 is press-fitted into the grooves of this completed head using a pump or the like.

As the nozzle substrate 1, glass, ceramics, plastic, and other suitable materials can be used. A conductive metal such as chromium, which has excellent adhesion to the nozzle substrate 1, is patterned onto the nozzle substrate 1 to a width of 50 μm to 2 mm, 1 to 2 mm using a thin film forming technique such as vacuum evaporation to form a metal film 3. form. Further, a photosensitive resin 4 is coated on the metal film 3 to form an insulating film.

The photosensitive resin 4 is a material that has excellent ink resistance and insulation properties, and has excellent adhesion to the substrate 1 and the metal film 3;
For example, polyimide resin (P.

1. Use Q) etc. In addition, the electrode 2 has excellent ink resistance in the part where the photosensitive resin 4 is removed by etching.
Gold (Au) and platinum (Pt) have appropriate hydrogen overvoltage and oxygen overvoltage and excellent corrosion resistance as electrolytic electrodes.
), nickel (Ni), iron (Fe).

Plating metals such as palladium (Pd) and silver (Ag),
Formed by vapor deposition or the like. When forming it, the thickness should be 5 to 20 μm, and the area in contact with the ink should be 2.5×1.
0-4. OX1oomn? Provided so that the

The electrodes 2 in the nozzle are arranged facing each other as shown in FIG. 4, and the distance between the electrodes is about 30 μm to 100 μm.

In the above configuration, the generation of ink droplets is shown in FIG.
To explain based on (d), initially, the ink 6 (aqueous ink) clogs all the way to the nozzle lower as shown in Fig. 5 (,), and then a predetermined voltage is applied between the electrodes 2. As shown in FIG. 5(b), gas 8 generated by electrolysis begins to be generated on the surface of the electrode 2, and as a result, a portion of the ink 6 overflows to the nozzle lower. As the electrolysis progresses further, bubbles 9 are generated that are large enough to divide the ink in the grooves 5, as shown in FIG. 5(C), and the nozzle lower ink is exposed along with the bubbles 9. When the bubble 9 grows, it becomes as shown in Fig. 5(d).
The ink on the nozzle opening side divided as shown in the figure is ink droplet 1.
It is ejected from the nozzle lower as 0. Figure (a) above
(d) Ink droplets are continuously ejected by repeating the process shown in the figure. Since the inner diameter of the nozzle is sufficiently small, bubbles are generated and ink droplets are ejected instantaneously, and ink droplets can be generated and ejected at high speed.

FIG. 6 shows another embodiment of the present invention, and is an example of a multi-nozzle system (6 nozzles). Basically,
The single nozzle (having the electrode 2) shown in FIGS. 2 to 4 is arranged in parallel on a pair of nozzle substrates 51 at a predetermined interval. Note that although the figure shows an example in which one nozzle substrate 51 is made into a flat plate and grooves are provided only in the other nozzle substrate 51, grooves may be provided in both substrates as in the previous embodiment. good. The spacing between the nozzles is 5° to 2°.

The width of the print head can be made the same as the width of the paper if necessary.

The operation of the above configuration is the same as that shown in Figures 2 and 4, so repeated explanation will be omitted (voltage is applied to the electrode 2 according to the print signal to cause electrolysis)
.

FIG. 7, FIG. 8, and FIG. 9 show a third embodiment of the present invention, in which a pair of nozzle substrates 31 formed in a U-shape, and a A wire electrode 32 embedded in a vertically penetrating hole, a metal film 33 as a conductor connected to the wire electrode 32 and formed on the surface of the nozzle substrate 31, and a coating on the surface to insulate the metal film 33. The head is completed by pasting the grooved surfaces of both substrates together with an adhesive or the like.

The nozzle substrate 31 can be made of the same material as in each of the embodiments described above. The wire electrode 32 has a diameter of 100 mm or more.
It is constructed by embedding and fixing a metal wire of a noble metal, such as Au, having a diameter of about 200 μm and a small electrical resistivity into a circular hole formed in the nozzle substrate 31. Also,
The metal film 33 is formed of a metal such as AI using a thin film forming technique such as vacuum deposition. The insulating film 34 coating this metal film 33 can be made of polyimide resin or the like.

In the above configuration, the generation of ink droplets is the same as that shown in FIGS. 5(a) to 5(d) described in the embodiments of FIGS. 2 to 4, and therefore the description thereof will be omitted.

FIG. 10 shows a fourth embodiment of the present invention, which is an example in which the embodiments shown in FIGS. 7 to 9 are multiplied. 7th
The single nozzle (wire electrode 32
a pair of nozzle substrates 51 at a predetermined interval
are arranged in parallel. Descriptions of the nozzle spacing, etc. and operation descriptions are the same as those of the embodiment shown in FIG. 6, and therefore will be omitted.

Fig. 11 0), ←) is an example in which the ink chambers are connected in the multi-nozzle embodiment described above.
The grooves communicating with the nozzles having the ink chamber 40 are commonly connected to the ink chamber 40. Ink is supplied to the ink chamber 40 from an ink supply port 41, and the ink in the ink chamber 40 permeates into the nozzle by capillary action.

FIG. 12 shows the metal film 3 (33) which functions as a lead wire in the embodiment of the present invention shifted from the position of the groove, and is bonded to the metal wire electrode 2 (32) with solder.

FIG. 13 shows a modification of the embodiment of the present invention.
One electrode 2 (32) provided in the nozzle is installed in the ink chamber 40 shown in FIGS. 11 and 12.

When applying voltage, apply a positive or negative potential to the electrode 2 (32) inside the nozzle, and apply a positive or negative potential to the electrode 2 (32) on the ink chamber 40 side.
A potential opposite to that of the electrode 2 (32) inside the nozzle is applied to generate air bubbles inside the nozzle. According to such a configuration,
This has the advantage that the manufacturing process for the electrodes provided on the head itself can be halved, making it easier to manufacture the head.

FIG. 14 shows an example of a schematic configuration of a printer constructed using the head shown above.

This system includes an ink pressure pump 21 that pumps ink from an ink tank 27, and a filter 22 that removes impurities mixed in the ink that is pumped by the pump 21.
an air chamber 23 into which ink is introduced through the filter 22; a head 24 which electrolyzes the ink in the air chamber 23 to generate air bubbles and generates ink droplets 17 from the air bubbles; and an electrode 2 of the head 24. A recording paper 26 is placed in the direction in which the ink droplets 17 are ejected.

In the above configuration, the ink in the ink tank 29 is pumped to the filter 22 by the pump 21. The ink from which impurities have been removed by the filter 22 is sent to the head 24 via the air chamber 23. On the other hand, when the print signal is input to the control section 25, the control section 25 controls the operation of the power supply section 28 according to the print signal. When the power supply unit 28 operates, a DC voltage is applied to the electrode 2 of the head 24, and water in the ink is electrolyzed.

This electrolysis generates hydrogen and oxygen gases, forming ink droplets 17, which are jetted onto recording paper 26. Therefore, the ink droplets 17 are attached to the recording paper 26 in accordance with the print signal.

〔Effect of the invention〕

According to the inkjet printer head of the present invention as described above, ink is electrolyzed in the nozzle portion and one ink droplet is generated by the bubbles generated at that time, so that ink droplets can be ejected at high speed and stably. can be done.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional inkjet printer head, and FIG. 2 is a side sectional view showing an embodiment of the present invention.
Fig. 3 is a plan sectional view of the embodiment shown in Fig. 1, Fig. 4 is a front view of the embodiment shown in Fig. 1, and Fig. 5 (a) * (b), (c
), (d) are explanatory diagrams showing the ink droplet generation process of the present invention, FIG. 6 is a perspective view showing the second embodiment of the present invention, and FIG.
The drawings are a side sectional view showing the embodiment of the invention shown in FIG. 3, FIG. 8 is a plan sectional view of the embodiment shown in FIG. 7, FIG. 9 is a front view of the embodiment shown in FIG. 7, and FIG. FIG. 11 is a perspective view showing the fourth embodiment of the present invention, FIG. FIG. 14 is a side sectional view showing a modification of the embodiment of the invention, and FIG. 14 is a configuration diagram showing an example of a printer to which the head of the invention is applied. Explanation of symbols 1.31.51... Nozzle substrate, 2.32... Electrode, 3.33... Metal film, 4... Photosensitive resin,
5... Groove portion, 34... Insulating film, 40...
ink chamber. Figure 1 ++ 12 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 1 Figure 7 Figure 8 Figure 3 Figure 9 Figure 10 Figure 1 Figure 11 (r3) Figure 12 Figure 13 Tin 14 Figure 4

Claims (1)

[Scope of Claims] An inkjet h printer head that ejects ink droplets from a nozzle toward recording paper according to a print signal, comprising: a first electrode disposed within the nozzle; and a second electrode that constitutes a counter electrode and electrolyzes moisture in the ink liquid interposed therebetween; An inkjet printer characterized in that it has a control means that applies a predetermined DC voltage between the second electrodes according to a print signal, generates gas by electrolysis, and causes ink particles to fly through the nozzle by the gas pressure. head.