JPH0615825A - Ink emitting device - Google Patents

Abstract

PURPOSE:To prevent electrolysis, to eliminate the deterioration of emitting performance due to electrolytic air bubbles and to drastically prolong the life of a current supply electrode with respect to conductive ink and the current supply electrode for boiling ink to emit the same by the pressure at the time of boiling. CONSTITUTION:Ink is supplied to an ink chamber 13a from an ink tank 18 filled with conductive ink through the pores 20 of a porous material 19 and potential is generated across an anode 11a and a cathode 12a by a power supply 15 and a switching element 14a to supply a current to the conductive ink in the ink chanaber 13a and the conductive ink is heated and boiled to emit the ink by the pressure fluctuations of the ink and the material qualities of at least the surfaces being in contact with the ink of the anode 11a and the cathode 12a are made optimum to drastically improve emitting performance and the life of electrodes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink ejecting apparatus for ejecting ink by the pressure generated by heating and boiling the ink.

[0002]

2. Description of the Related Art In recent years, an ink jet printer using an ink ejecting device has come to be widely used as an output printer for an office computer because of its freshness in printing.

A conventional device is US Pat. No. 3,179,042.
The device described in the specification and the drawing is known, which energizes a conductive ink to vaporize the ink itself by Joule heat, and ejects an ink droplet on the surface to be printed by its expansion pressure. It is intended to be. FIG. 5 is a sectional view of a conventional ink ejection device. In FIG. 5, 1 is a conductive ink, 2 is an ink chamber filled with the conductive ink 1, 3 is an ink tank containing the conductive ink 1, 4,
5 is a pair of electrodes arranged below the liquid surface of the conductive ink 1, 6 is a power supply, 7 is a switch for the power supply 6, 8 is a nozzle for discharging the conductive ink 1, 9 is a surface to be printed, 10 is a nozzle 8 It is an ink droplet ejected from.

A conventional ink ejection device will be described below. First, when a voltage is applied to the pair of electrodes 4, 5, a current flows in the conductive ink 1, and the Joule heat of the current causes the electrodes 4, 4.
Part of the conductive ink 1 between the tips of 5 is vaporized. Further, the vaporized vapor of the conductive ink 1 expands until a sufficient pressure is generated to eject the ink droplet 10 from the nozzle 8 onto the surface 9 to be printed. By selecting the electrode to which the voltage is applied by the switch 7, it is possible to select a nozzle hole for ejecting the conductive ink 1 and form a desired character on the surface 9 to be printed.

[0005]

However, in the above conventional structure, generally, when electricity is applied while the electrode is exposed to a conductive aqueous solution, electrolysis of water occurs and hydrogen or oxygen bubbles are generated, Prevents normal ink ejection. Further, there is a problem that the electrodes cause a dissolution reaction with respect to the ink, especially at the anode, so that the distance between the electrodes remarkably increases and it becomes impossible to conduct electricity.

[0006]

SUMMARY OF THE INVENTION To solve this problem, the present invention uses an anode of a pair of electrodes provided in an ink chamber containing a conductive ink, at least a surface of which is in contact with the conductive ink. And made the cathode different.

[0007]

According to the present invention, the above structure makes it possible to easily process the electrode and prevent the electrolysis electrode from dissolving in the conductive ink.

[0008]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a multi-nozzle configuration of an ink ejection device according to a first embodiment of the present invention as viewed from an ejection port. In FIG. 1, 11a, 11b,
Reference numerals 11c, 11d and 11e are anodes, and switching elements 14a, 14b, 14c and 1 connected to the respective anodes.
It is connected to the positive terminal of the power supply 15 via 4d and 14e. Reference numerals 12a, 12b, 12c, 12d and 12e are cathodes and are connected to the negative terminals of the power supply 15, respectively. 13a, 13b, 13c, 13d and 13e are each 1
An ink chamber filled with conductive ink sandwiched between 1a to 11e as an anode and 12a to 12e as a cathode, and the inside of the ink chambers 13a to 13e by selectively turning on any of the switching elements 14a to 14e. The selected ink is heated and boiled by electric heating and ejected, and desired printing is performed. In the present invention, the anodes 11a to 11e and the cathode 12 are
Since at least the surface of a to 12e in contact with the ink is different between the anode and the cathode, the electrolytic bubbles and the electrodes are prevented from being dissolved in the ink.

The operation of the ink ejecting apparatus constructed as above will be further described with reference to FIG. 2 is a sectional view taken along the line AA of FIG. In FIG. 2, 11a is an anode, 12a is a cathode, 13a is an ink chamber filled with conductive ink, 14a is a switching element, 15 is a power supply,
16 and 17 are base materials on which the anode 11a and the cathode 12a are arranged, 18 is an ink tank, 19 is a porous material, 2
0 is a fine hole. First, by closing the switching element 14a, the power source 15 causes the anode 11a and the cathode 12a to be closed.
When a voltage is applied between them, a current I flows through the conductive ink in the ink chamber 13a as shown in the figure, and the conductive ink in the portion where the current I flows self-heats, and finally boiling begins to cause bubbles. Occurs. As a result, the conductive ink near the nozzle holes 25 receives the pressure of the bubbles and is ejected from the nozzle holes 25 and adheres to the recording paper (not shown) to form dots. The consumed conductive ink is constantly supplied from the ink tank 18 to the ink chamber 13a through the fine holes 20 of the porous material 19. This porous material 19 is selected such that the hole diameter and the opening ratio of the fine holes 20 are balanced with the fluid resistance with respect to the nozzle holes 25 so that the power of ink ejection is optimized. Generally, when an electric current is applied between the anode 11a and the cathode 12a, hydrogen and oxygen bubbles are generated by electrolysis of water.
Dissolution of a into the conductive ink occurs. Therefore, at least the portion of the anode 11a that is in contact with the conductive ink needs to be selected from a material that does not cause electrolysis, and the conductive ink must be heated and boiled with a minimum energization time.

(Table 1) shows that electrodes of φ50 μm are opposed to each other,
This is a summary of the results of testing various electrode materials for the amount of wear and the state of bubbles when a pulse of 40 V and 20 μs was applied 2 million times at a frequency of 3 kHz through a conductive liquid of 20 Ωcm.

[0011]

[Table 1]

As can be seen from the above results, the anode 11a
At least the surface in contact with the conductive ink of, for example,
Material such as titanium or platinum-based or titanium-based alloy, cathode 1
At least the surface of 2a that is in contact with the conductive ink is preferably made of a material such as titanium, nickel, or tungsten.
In terms of cost, titanium is expensive and difficult to process. Therefore, nickel, tungsten or the like is preferable for the cathode 12a in terms of cost and easiness of patterning. Specifically, for example, it is preferable that both the anode 11a and the cathode 12a be patterned with nickel, and titanium be sputtered on at least the surface of the anode 12a which is in contact with the conductive ink. The energization time is preferably about 20 μs or less.

(Embodiment 2) FIG. 3 is a plan view seen from an ejection port showing a multi-nozzle of an ink ejection device according to a second embodiment of the present invention. 21a, 21b, 2 in FIG.
1c, 21d, 21e and 21f are electrodes, and 21b and 21
Reference numerals d and 21f are anodes, and reference numerals 21a, 21c and 21e are cathodes. 22a, 22b, 22c, 22d and 22e are ink chambers, and one electrode is common to two ink chambers.
23a, 23b, 23c, 23d, 23e and 23f are switching elements, and 23a, 23c and 23e are respectively cathodes 21a, 21c and 21e, and 23b, 23d and 23f.
Is connected to the anodes 21b, 21d, 21f. 24
Is a power supply, and switching elements 23a, 23b, 23c,
By selectively turning on the adjacent pair of 23d, 23e, and 23f, the ink chambers 22a, 22b, and 22
Selected ones of the conductive inks in c, 22d, and 22e are heated and boiled by electrification to eject the conductive ink to perform desired printing. These electrodes 21a, 21b, 21c, 2
By making at least the surface of 1d, 21e, and 21f in contact with the conductive ink different between the anode and the cathode,
Electrolysis bubbles and electrodes 21a, 21b, 21c, 21
It is possible to prevent dissolution of d, 21e, and 21f in the conductive ink.

The detailed operation of the ink discharge device having the above structure will be described with reference to FIG. FIG. 4 is a sectional view taken along the line BB in FIG. 21a and 21c are cathodes, 21b and 21d are anodes, 22a, 22b and 22c are ink chambers filled with conductive ink, and 23a and 23c are switching elements connected to the cathodes 21a and 21c.
3b and 23d are switching elements connected to the anodes 21b and 21d, 24 is a power supply, 25 is an ink tank, and 26 is a porous material that supplies conductive ink from the ink tank 25 to the ink chamber with appropriate fluid resistance. is there. Now, when the switching elements 23a and 23b are turned on, the anode 21b
A current I flows from the cathode 21a to the conductive ink in the ink chamber 22a, and the conductive ink is heated and boiled, and the conductive ink is ejected by the pressure of the bubbles. Similarly, switching elements 23b and 23
When c is turned on, the conductive ink is ejected from the ink chamber 22b, and when the switching elements 23c and 23d are turned on, the conductive ink is ejected from the ink chamber 22c. Here, it is very effective to optimize the material of at least the surface of the anode and the cathode which is in contact with the conductive ink, against the electrolysis of the conductive ink and the wear of the electrode. As in the example.

[0015]

According to the present invention, at least a pair of electrodes provided in an ink chamber containing a conductive ink has a surface material in contact with the conductive ink which is different between the anode and the cathode. In addition to making it easier to process, it is possible to prevent the electrolysis electrode from dissolving in the conductive ink, the ink ejection is good, and the life of the electrode can be extended and the manufacturing cost can be suppressed.

[Brief description of drawings]

FIG. 1 is a plan view of an ink ejection device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the ink ejection device according to the first embodiment of the present invention.

FIG. 3 is a plan view of an ink ejection device according to a second embodiment of the present invention.

FIG. 4 is a sectional view of an ink ejection device according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a conventional ink ejection device.

[Explanation of symbols]

 11a Anode 11b Anode 11c Anode 11d Anode 11e Anode 12a Cathode 12b Cathode 12c Cathode 12d Cathode 12e Cathode 13a Ink Chamber 13b Ink Chamber 13c Ink Chamber 13d Ink Chamber 13e Ink Chamber 14a Switching Element 14b Switching Element 14d Switching Element 14d Switching Element 14c 14d 15 power supply 18 ink tank 19 porous material 20 fine pores

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomoyuki Noguchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. An ink chamber containing a conductive ink, a nozzle formed in a part of the ink chamber, and a pair of electrodes provided in the ink chamber, wherein a voltage is applied to the pair of electrodes. An ink discharge device for discharging ink by heating and boiling bubbles of the conductive ink between the electrodes, wherein at least the surface material in contact with the conductive ink of the pair of electrodes is an anode An ink ejection device characterized in that the cathode and the cathode are different. 2. The ink chambers are provided adjacent to each other, and a part of a wall for separating the ink chambers adjacent to each other is formed by an electrode common to the two ink chambers adjacent to each other. The ink ejecting apparatus according to claim 1, wherein the anode and the cathode are alternately arranged along the order of the chambers.