JPH0890775A - Ink-jet apparatus and conductive ink - Google Patents

Abstract

PURPOSE: To enhance a discharging force from a nozzle and achieve super fine printing. CONSTITUTION: A conductive ink 20 is obtained by dispersing a conductive material 22 in an ink 21 having conduction properties. The conductive material 22 has a higher conductivity than the ink 21. Electrodes 7 and 9 confront each other via the conductive ink 20 in a storing space 5. An alternative current is applied between the electrodes 7 and 9. The current concentrates on the conductive material 22 having the higher conductivity and moreover concentrates on the surface of the conductive material 22 because of the skin effect. Since there are many conductive materials 22 present in the space held between the electrodes 7 and 9, the total surface area of the conductive materials 22 generating heat, is considerably large. A large amount of current can thus be supplied to inject thermal energy intensively to the ink 21. The ink generates bubbles by the heat and the pressurized ink is discharged out from a nozzle 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet device capable of forming a recorded image having a high density, and a conductive ink effectively applied to the ink jet device.

[0002]

2. Description of the Related Art As a principle of a conventional ink jet apparatus, a bubble jet method, an energized jet method, etc. are known. The bubble jet method is a method of vaporizing ink in a container by heat generated by a resistance heating element to generate bubbles, and ejecting ink having a high pressure from a nozzle of the container. The energization jet method is a method in which a conductive ink is heated by energization, the heat vaporizes the ink to generate bubbles, and the ink having a high pressure is ejected from a nozzle of a container.

[0003]

In the bubble jet method using a resistance heating element, ink contacting the heating surface of the resistance heating element is vaporized by heating. That is, since heat is applied to the ink from the heating surface of the resistance heating element, the limit of the energy that can be injected into the ink is defined by the area of the heating surface of the resistance heating element, and thus the ink ejection energy is also limited. If more current is applied to the heating resistor to heat the ink beyond this limit, the resistance heating element may be destroyed without increasing the ink ejection force.

Further, in the energization jet method, the electrically conductive ink to be energized has a uniform composition and its resistance value is constant, so that the energy injected into the ink is increased to increase the ink ejection force. There was no way to do it.

In recent years, it has been desired to increase the density of printed dots in an ink jet device to improve the definition. For this purpose, it is necessary to make the hole diameter of the nozzles for ejecting the ink and the arrangement pitch of the nozzles smaller than before. However, as described above, the conventional bubble jet method cannot easily increase the ink ejection force. If the hole diameter and the arrangement pitch of the nozzles are reduced while maintaining the ink ejection force as it is, ink residue or dust is likely to be accumulated in the nozzles, which may cause clogging of the nozzles. As described above, the conventional inkjet device has a problem that it is difficult to improve the definition of printing because the ejection force of the ink is limited.

An object of the present invention is to provide an ink jet device which has a high ejection force from a nozzle and can cope with high definition printing, and a conductive ink which is effective when applied to the ink jet device. .

According to another aspect of the present invention, there is provided an ink jet device, in which a conductive ink containing a conductive material and a conductive ink is stored, and an alternating current is passed through the conductive ink in the storage space. Then, it has an electrode for foaming the conductive ink and a nozzle for ejecting the conductive ink foamed by the application of an alternating current.

An ink jet device according to a second aspect is the ink jet device according to the first aspect, wherein the conductivity of the conductive material is higher than the conductivity of the ink.

According to a third aspect of the present invention, in the ink jet device according to the second aspect, the conductive material has conductivity on at least the surface thereof, and the conductivity thereof is the skin effect due to an alternating current. It is characterized in that it has a conductivity that generates heat enough to foam the conductive ink.

An ink jet device according to a fourth aspect is the ink jet device according to the third aspect, wherein the conductive material is smaller than the nozzle.

According to a fifth aspect of the present invention, in the ink jet device according to the fourth aspect, the storage space has a pair of substrates facing each other at a predetermined interval.
It is composed of a plurality of storage spaces that are arranged in a line and are partitioned by a plurality of partition members that are arranged between the pair of substrates at a predetermined interval from each other, and the nozzle is provided at each one end of each of the storage spaces. A plurality of nozzles that are opened and arranged in a line, and the electrodes include a plurality of first electrodes that are provided on the inner surface of one substrate for each of the storage spaces,
An alternating power source configured to have a plurality of pairs of electrodes configured to include a second electrode commonly provided on the inner surface of the other substrate; and an alternating power source for applying an alternating current between the first and second electrodes; It is characterized in that it has a plurality of switching means respectively provided in the first electrode and a supply means for supplying the conductive ink to each of the storage spaces.

According to a sixth aspect of the present invention, there is provided the ink jet device according to the fourth aspect, wherein the storage space faces a pair of substrates which are opposed to each other at a predetermined interval.
It is composed of a plurality of storage spaces that are arranged in a line and are partitioned by a plurality of partition members that are arranged between the pair of substrates at a predetermined interval from each other, and the nozzle is provided at each one end of each of the storage spaces. It is composed of a plurality of nozzles that are opened and arranged in a line, and the electrodes are composed of a plurality of pairs of electrodes that are independently provided for each of the storage spaces, and further, are provided as a pair in each of the storage spaces. An alternating power source for applying an alternating current between the electrodes, a plurality of switching means provided for each electrode in the storage space, and a supply means for supplying the conductive ink to each storage space are characterized. .

According to a seventh aspect of the present invention, in the ink jet device according to the fourth aspect, the electrodes are constituted by a plurality of longitudinal electrodes arranged at a predetermined interval so as to be parallel to each other. The accommodating space is composed of a plurality of accommodating spaces that are arranged in a line and are partitioned by the electrodes and a pair of insulating members that face each other with the electrodes interposed therebetween, and the nozzle is provided at each one end of each accommodating space. It is composed of a plurality of nozzles that are opened and arranged in a line, and further selects an alternating power source that applies an alternating current to two adjacent electrodes and two adjacent electrodes to which an alternating current is applied from the plurality of electrodes. Switching means,
It is characterized by having a supply means for supplying the conductive ink to each of the storage spaces.

The conductive ink according to claim 8 is characterized in that it has conductive ink and a conductive material dispersed in the ink and having higher conductivity than the ink.

The conductive ink according to a ninth aspect is the conductive ink according to the eighth aspect, wherein the conductivity of the conductive material is higher than the conductivity of the ink.

The conductive ink according to claim 10 is
The conductive material has conductivity at least on its surface,
It is characterized in that the conductivity is a conductivity that generates heat enough to foam the ink by a skin effect due to an alternating current.

[0017]

According to the structure of the present invention described above, an alternating current is applied between the electrodes to energize the conductive ink in the storage space. The alternating current flows through the conductive material having a higher conductivity than that of the ink, and in particular, it flows concentratedly on the surface of the conductive material due to the skin effect. The conductive ink in the storage space sandwiched between the pair of electrodes contains a large number of conductive materials, and since the total surface area of these conductive materials is large, more energy is injected into the conductive ink than before. be able to. The heat generated on the surface of the conductive material heats the ink to foam it, and the conductive ink having the increased pressure is ejected from the nozzle.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink jet device 1 of a first embodiment will be described with reference to FIGS. On the upper surface of the insulating first substrate 2, a plurality of elongated rod-shaped partitioning members 3 are arranged at predetermined intervals. The tip end of each partition member 3 is formed wide, and the front end face thereof coincides with the front end face of the first substrate 2.
A second substrate 4 is provided on these partition members 3. Between the partition members 3 and 3 which are adjacent to each other at a predetermined interval, the first substrate 2 and the second substrate 4, there are a plurality of substantially rectangular tube-shaped storage spaces 5 in which the conductive ink 20 is stored. It is configured. Further, a rectangular nozzle 6 for ejecting the conductive ink 20 inside is opened at the front end surface of each of the storage spaces 5.

Electrodes 7 are provided on the first substrate 2 in the storage spaces 5, respectively. The electrode 7 is a part of a strip electrode provided for each storage space 5. The end portion of each strip electrode is left as the electrode 7, and the other portion is covered with the insulating film 8.

An electrode 9 is formed on one surface of the lower surface of the second substrate 4. The electrode 9 forms a pair with each of the electrodes 7 and is commonly formed for each of the electrodes 7. The electrodes 9 and the electrodes 7 are thin films or thick films made of various conductive materials, and can be formed by a simple method such as printing or plating.

As shown in FIG. 2, an alternating power source 10 is connected between each of the electrodes 7 and 9. Each electrode 7
Each of them is provided with a switching means 11 so that a voltage can be applied to the pair of electrodes 7 and 9 in a desired storage space 5 so that the conductive ink 20 between the electrodes can be energized.

The ink jet device 1 has a conductive ink 2
It has zero supply means. This supply means, for example,
The structure may be such that an ink supply pipe led from an ink supply means is connected to the opening end of each storage space 5 opposite to the nozzle 6. With such a supply means, each storage space 5
The conductive ink 20 is constantly filled therein.

The conductive ink 20 is, for example, 1 × 10.
^The ink 21 having a conductivity of ⁷ Ωcm or less is mainly used. The ink 21 contains a conductive material 22 having higher conductivity than the ink 21. This conductive material 2
The material 2 is preferably a material having conductivity at least on its surface, such as carbon particles, metal particles, fine particles coated with carbon, and microcapsules having conductivity on its surface. The conductive material 22 has, for example, a diameter of 0.
When the particle size is in the range of 01 to 10 μm, a good result can be obtained for heat generation due to the skin effect described later, and it is desirable that the size is such that the nozzle 6 is not clogged.

Further, in this embodiment, the conductive ink 20 is used.
The alternating current passing through the conductive material 22 inside is limited to the surface layer surface of the conductive material 22 which is a conductor and does not enter the inside, but flows only on the surface of the conductive material 22. This phenomenon is called the skin effect. In the present embodiment, the electric current concentrates on the surface of the conductive material 22 due to the skin effect, and the effective resistance of the conductive material 22 increases. As a result, the surface of the conductive material 22 generates heat and bubbles are generated in the ink. Therefore, it is preferable that the surface or the vicinity of the surface of the conductive material 22 has a resistance capable of generating heat enough to generate bubbles by energization with the skin effect.

As described above, the conductive material 22 preferably has higher conductivity than the ink 21 which is the main component of the conductive ink 20, and at least the surface thereof has a certain resistance value. It is preferable.

Next, the alternating current applied between the electrodes 7 and 9 by the alternating power source 10 in this embodiment will be described. The alternating current described in the present embodiment and claims is a term that broadly refers to a current other than a direct current whose current value changes and which exhibits the skin effect. Therefore, the waveform includes not only a sinusoidal current but also a sinusoidal wave that appears only on one side of the positive and negative sides. It also includes pulse waves appearing on both positive and negative sides as shown in FIG. 3 or FIG. Furthermore, it also includes a pulse wave that appears only on one side, positive or negative. Further, the shape of the pulse wave does not have to be a regular rectangle as shown in FIG. 3, and the sine wave waveform may be distorted.

Further, in the alternating current of this embodiment, the skin effect becomes more remarkable as the frequency of the sine wave or the pulse wave is higher, and the current concentrates on the surface of the conductive material 22 to increase the effective resistance, thereby increasing the thermal resistance. Is more likely to occur, which is preferable. Electrode 7,
By appropriately setting the frequency and current value of the alternating current applied between 9 and 9, the concentration of the conductive material 22 in the conductive ink 20, the conductivity or the resistance value of the conductive material 22, and the like, the conductive ink 20 generates heat. The amount can be controlled arbitrarily.

In the conventional ink jet device which generates ink bubbles by heating the ink which is in direct contact with the resistance heating element, only the area of the resistance heating element is the heating area. Unlike this, the heating surface of the inkjet device 1 of the present embodiment is
Conductive ink 20 in a space sandwiched by a pair of electrodes 7 and 9
Is the surface of a large amount of the conductive material 22 and the total surface area of these conductive materials 22 is large, so more energy can be injected than in the conventional case. Therefore, it is easy to increase the ink ejection force, and it is easy to improve the printing quality by making the inner diameter and the arrangement pitch of the nozzles 6 smaller than before.

The operation of the above configuration will be described. An alternating current such as a pulse wave illustrated in FIG. 3 or 4 is applied between the electrodes 7 and 9. As shown in FIG.
The electric current does not flow uniformly in the conductive ink 20, but collects in the conductive material 22 having higher conductivity than the ink 21. At this time, due to the skin effect, the current flows through the conductive material 22.
Concentrate on the surface of. Since the surface of the conductive material 22 has an appropriate electric resistance, the electric current concentrated on the surface by the skin effect generates heat. The conductive ink 20 in the space sandwiched by the pair of electrodes 7 and 9 contains a large number of conductive materials 22, and the total surface area of the particles of the conductive material 22 that come into contact with the ink 21 is very large. Therefore, it is possible to flow a larger amount of electric current than in the conventional case and concentrate the heat energy into the ink 21 to inject it.

As shown in FIG. 6A, the conductive material 22
When a current flows through the surface of the conductive material 22, heat particularly concentrates at two places on the surface of the conductive material 22 where the current flows in and out, and small bubbles 23 are generated in the ink adjacent to this portion. The bubble 23 generated as shown in FIG. 7B becomes large, and the two bubbles 23 are merged into one as shown in FIG. As shown in (d) and (e) of the figure, when the power supply is stopped and the heat generation is subsided, the bubble 23 rapidly becomes smaller.

In the conductive ink 20 between the electrodes 7 and 9, FIG.
When a bubble is generated in the above process illustrated in FIG.
As shown in (a) to (e), the conductive ink 20 in the storage space 5 receives pressure and is ejected from the front nozzle 6. The graphical symbols (a) to (e) in FIG. 7 correspond to the graphical symbols (a) to (e) in FIG.

In the present ink jet device 1 shown in FIG. 1, the switching means 11 in the circuit of FIG. 2 is appropriately switched to eject ink from a desired nozzle 6 at a desired timing. The ejected ink adheres to the printing paper in front of each nozzle 6 in a predetermined direction in a dot shape. A desired image is printed on the printing paper.

FIG. 8 shows an ink jet device 3 of the second embodiment.
It is a partially notched perspective view showing 1. The parts corresponding to those in the first embodiment are designated by the same reference numerals as those in FIG. 1 and their description is omitted. Electrodes 32 and 33 are provided on the first substrate 2 in the storage space 5 so as to face each other at a predetermined interval. Electrode 3
3 is formed in a band shape, an insulating film 34 is partially exposed on the insulating film 34, and the electrode 33 is formed in a band shape on the insulating film 34. Both electrodes 32 and 33 are connected to a drive circuit at the end of the first substrate 2 opposite to the nozzle 6. There is no electrode on the inner surface of the second substrate 4. FIG. 10 is a diagram showing the drive circuit of the embodiment shown in FIG. 8, in which the electrode pairs 3 in each storage space 5 are arranged.
2, 33 can be driven individually with an alternating current. According to this embodiment, the same effect as that of the first embodiment can be obtained.

FIG. 9 shows an ink jet device 4 of the third embodiment.
It is a partially notched perspective view showing 1. On the substrate 42 which is an insulating member, strip electrodes 43 are arranged at a predetermined interval. A pair of adjacent electrodes 43, 43 constitutes a set, and each is connected to the alternating power source 10. The switching means 11 is provided for each electrode pair 43, 43, and an alternating current is selectively applied to each electrode pair 43, 43 at a desired timing.

The electrode 43 on the substrate 42 is covered with a film 44 which is an insulating member. A pair of adjacent two electrodes 43, 43, the substrate 42, and the coating 44 form a storage space 45 for the conductive ink 20. The front end face of the storage space 45 is opened, and the conductive ink 2
The nozzle 46 that discharges 0 is used. The means for supplying the conductive ink 20 to the storage space 45 may be the same as in the first embodiment.

In front of the nozzle 46, the platen roller 4
7 are provided. The printing paper 48 is conveyed in accordance with the rotation of the platen roller 47, and the inkjet device 41 is driven in synchronization with this. The switching means 11 is appropriately switched, and ink is ejected from a desired nozzle 46 at a desired timing. The ejected ink adheres to the printing paper 48 in a dot shape, and a desired image is printed.

The operations such as energization between the electrodes in the second and third embodiments, heat generation due to the skin effect, bubble generation, and ink ejection are the same as those in the first embodiment. In the case of the second and third embodiments, the electrode pairs 32, 33 and 43, 43 corresponding to the respective nozzles 6, 46 are electrically divided, so that the driving force flowing between certain electrode pairs can be eliminated. Current is less likely to affect the electrode pairs adjacent to it. If the one electrode 9 of the electrode pair is a common electrode between the pairs as in the first embodiment, the manufacture becomes easy. Further, in the third embodiment shown in FIG. 9, the distance between the adjacent electrodes 43, 43 and the opening width of the nozzle 46 are the same. However, the distance between the tips of the adjacent electrodes 43, 43 may be reduced. The opening of the nozzle may be made smaller by reducing the height of the electrode 43.

[0038]

According to the ink jet device and the conductive ink of the present invention, an alternating current is applied to the conductive ink containing the conductive material, and the skin current effect collects the alternating current on the surface of the conductive material to concentrate heat. The ink is ejected at a high pressure by increasing the energy density. Therefore, the inner diameter of the nozzle and the arrangement pitch can be reduced, and high-definition printing can be performed.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a first embodiment.

FIG. 2 is a drive circuit diagram of the first embodiment.

FIG. 3 is a waveform diagram showing an example of an alternating current in the first embodiment.

FIG. 4 is a waveform diagram showing an example of an alternating current in the first embodiment.

FIG. 5 is a conceptual diagram showing an energized state of an alternating current in the first embodiment.

FIG. 6 is a diagram showing a state in which bubbles are generated in the conductive ink in the first embodiment.

FIG. 7 is a diagram showing a state in which bubbles are generated in the conductive ink and the ink is ejected in the first embodiment.

FIG. 8 is a partially cutaway perspective view of the second embodiment.

FIG. 9 is a partially cutaway perspective view of a third embodiment.

FIG. 10 is a drive circuit diagram of the second embodiment.

[Explanation of symbols]

 1, 31, 41 Ink jet device 5,45 Storage space 6,46 Nozzle 7, 9, 32, 33, 43 Electrode 20 Conductive ink 22 Conductive material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B41M 5/00 E C09D 11/00 PSZ B41J 3/04 102 Z

Claims (10)

[Claims] 1. A storage space in which a conductive ink containing a conductive material and an ink having conductivity is stored, and an alternating current is passed through the conductive ink in the storage space to foam the conductive ink. An inkjet device having an electrode and a nozzle for ejecting the conductive ink foamed by applying an alternating current. 2. The ink jet device according to claim 1, wherein the conductivity of the conductive material is higher than the conductivity of the ink. 3. The conductive material has conductivity at least on its surface, and the conductivity thereof is a conductivity for generating heat enough to foam the conductive ink due to a skin effect due to an alternating current. 2. The inkjet device according to 2. 4. The inkjet device according to claim 3, wherein the conductive material is smaller than the nozzle. 5. The inkjet apparatus according to claim 4, wherein the storage space includes a pair of substrates facing each other at a predetermined interval, and a plurality of substrates arranged at a predetermined interval between the pair of substrates. It is configured by a plurality of storage spaces that are arranged in a line partitioned by a partition member, the nozzle is configured by a plurality of nozzles that are opened in one end of each of the storage spaces and arranged in a line, and the electrodes are A plurality of pairs of electrodes configured by a plurality of first electrodes provided on the inner surface of one substrate for each storage space and a second electrode commonly provided on the inner surface of the other substrate, Further, an alternating power source for applying an alternating current between the first and second electrodes, a plurality of switching means provided in the first electrode, and a supply device for supplying the conductive ink to each of the storage spaces. Ink jet apparatus and means. 6. The inkjet apparatus according to claim 4, wherein the storage space includes a pair of substrates facing each other at a predetermined interval and a plurality of substrates arranged at a predetermined interval between the pair of substrates. It is configured by a plurality of storage spaces that are arranged in a line partitioned by a partition member, the nozzle is configured by a plurality of nozzles that are opened in one end of each of the storage spaces and arranged in a line, and the electrodes are It is composed of a plurality of pairs of electrodes provided independently for each storage space, and further, an alternating power source for applying an alternating current between the electrodes provided in pairs in each storage space, and each electrode of the storage space. An inkjet device having a plurality of switching means provided and a supply means for supplying the conductive ink to each of the storage spaces. 7. The ink jet device according to claim 4, wherein the electrodes are composed of a plurality of longitudinal electrodes arranged at a predetermined interval so as to be parallel to each other, and the storage space includes the electrodes. A plurality of storage spaces that are arranged in a row and that are partitioned by a pair of insulating members that face each other with the electrode interposed therebetween, and the nozzles that are opened in one end of each of the storage spaces and that are arranged in a row. Further, an alternating power source for applying an alternating current to the two adjacent electrodes, a switching means for selecting the adjacent two electrodes to which the alternating current is applied from the plurality of electrodes, and An inkjet device comprising: a supply unit that supplies the conductive ink. 8. A conductive ink comprising a conductive ink and a conductive material dispersed in the ink and having a higher conductivity than the ink. 9. The conductive ink according to claim 8, wherein the conductivity of the conductive material is higher than the conductivity of the ink. 10. The conductive material has conductivity at least on its surface, and the conductivity thereof is a conductivity for generating heat enough to foam the ink by a skin effect by an alternating current. Conductive ink.