JPH035150A - Device and method for ink jet recording - Google Patents

Abstract

PURPOSE:To easily perform printing with small dots and gradation expression by a method wherein an ultrasonic vibration is applied to a recording electrode by an ultrasonic exciting means to form a projected ink meniscus on the top end of the recording electrode, and voltage is applied between the recording electrode and a counter electrode in accordance with image information by a voltage application control means. CONSTITUTION:A recording head 5 consists of an ink containing part 2, a recording electrode 3, and an ultrasonic exciting means 4. On the opposed position, a roll-form counter electrode 6 which functions also as a surface for holding a recording sheet 25 is disposed at a predetermined interval. By applying a pulse voltage between the recording electrode 3 and the counter electrode 6 in accordance with image information by a voltage application control means 7, an electric field is formed between the recording electrode 3 and the counter electrode 6. Since a meniscus 14 of an ink I has a projected form, the electric field converges on the tip end of the projected ink meniscus 14. The action of an attracting force caused by the converging electric field makes the meniscus 14 cobwebbed in a tapered form as it approaches the tip end, thereby forming an ink dot 31 on the surface of the recording sheet 25. The ink dot 31 is infiltrated into the recording sheet 25, and fixed on the recording sheet 25 by the evaporation of the solvent to atmosphere.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention uses ultrasonic vibration to form a convex ink meniscus, and this convex meniscus-shaped ink is ejected by an electrostatic field to record an image. This invention relates to a new type of inkjet recording device.

[Prior Art] Conventionally, as an inkjet recording device, there are, for example, the following ones. That is, as shown in FIG. 9, the recording head 100 includes a pair of insulating substrates 101 and 102.
are arranged parallel to each other and facing each other, and both assembly boards 101.1
In addition to forming an ink holder 811103 between 02 and 102, a slit-shaped ink discharge port 104 is formed at the tip of both assembly edge substrates 101 and 102. By supplying the ink 105 at a predetermined pressure to the ink holding section 103, the ink female scum 106 in the ink discharge port 104 is recessed.
form. Further, on one inner surface of the insulating substrate 102, a large number of electrostatic field applying electrodes 107, 107, . . . are formed at a predetermined pitch along the longitudinal direction of the ink ejection port 104. Further, a counter electrode 109 is arranged at a position facing the recording head 100 with a recording paper 108 interposed therebetween.

And electrodes 107, 107, etc. of the recording head 100.
A high voltage is selectively applied according to the image signal to form an electrostatic field between the electrode 107 to which this voltage is applied and the facing electrode 109, and the string 110 of the ink 105 is recorded by this electrostatic field. The ink is allowed to grow toward the paper 108 side, and the ink 105 is deposited on the recording paper 108 in accordance with image information, thereby recording an image.

[Problems to be Solved by the Invention] However, the above-mentioned prior art has the following problems. That is, in the inkjet recording apparatus, a concave ink meniscus 106 is formed in the ink ejection port 104 of the recording head 100, and electrostatic field applying electrodes 107.1°07...
By selectively applying an electrostatic field, an electrostatic attraction force is applied to the concave ink meniscus 106 in the area where the electrostatic field is applied, and the ink string 110 grows toward the recording paper 108 to record an image. This is what we do. Therefore, since the shape of the ink meniscus 106 is concave, it is difficult to concentrate an electrostatic field on the ink meniscus 106, and in order to exert a sufficient electrostatic attraction force on the ink 105, the applied voltage must be set by a high-voltage power source. Since there are limitations due to the capacity, etc., it is necessary to narrow the distance between the recording head 100 and the counter electrode 108. As a result, the gap between the recording head 100 and the counter electrode 108 becomes smaller, which poses a problem in that it is difficult to respond to changes in the thickness of the recording paper 108. Further, since it is difficult to concentrate the electrostatic field on the ink meniscus 106, a sufficient electrostatic attraction force does not act on the ink 105, and it is difficult to form a thin string 110 of the ink 105. Therefore, you can record small dots,
There was a problem in that it was difficult to record images with gradation.

[Means for Solving the Problems] Therefore, the present invention has been made to solve the above problems of the prior art, and its purpose is to reliably and stably form a convex ink meniscus. By doing so, it is possible to increase the distance between the recording head and the counter electrode, and it is possible to easily respond to changes in the thickness of recording paper, etc., and it is also possible to easily print small dots and express gradation. An object of the present invention is to provide an inkjet recording device.

An inkjet recording apparatus according to the present invention includes an ink storage section that stores ink, and an ultrasonic vibration means that applies ultrasonic vibration to any recording electrode of a needle-shaped recording electrode disposed in the ink inside the ink storage section. a recording head having;
The recording head is configured to include a counter electrode disposed at a position facing the ink storage portion of the recording head, and a voltage application control means for applying a voltage between the recording electrode and the counter electrode according to image information. There is.

Further, the inkjet recording method according to the present invention uses the above inkjet recording apparatus, applies ultrasonic vibration to the recording electrode by the ultrasonic vibration means to form a convex meniscus of ink at the tip of the recording electrode, and By applying a voltage between the recording electrode and the counter electrode according to the image information by the voltage application control means, the ink in the convex meniscus is ejected toward the counter electrode, and onto the recording sheet disposed on the surface of the counter electrode. The camera is configured to record images.

[Function] In the inkjet recording device according to the present invention, as described in the configuration of the inkjet recording device, ultrasonic vibration is applied to the recording electrode by the ultrasonic vibration means to form a convex meniscus of ink at the tip of the recording electrode. At the same time, by applying a voltage between the recording electrode and the counter electrode according to the image information using the voltage application control means, the ink of the convex meniscus is ejected toward the counter electrode,
An image is recorded on a recording sheet placed on the surface of the counter electrode.

In this way, since a convex ink meniscus is formed and a one-degree image is recorded, the electrostatic field can be concentrated on the convex ink meniscus and the ink can be ejected, thereby increasing the distance between the recording head and the opposing electrode. By setting this, it is possible to respond to changes in the thickness of the recording sheet, and it is also possible to form small dots and express gradation.

[Example] The present invention will be explained below based on illustrated embodiments.

FIG. 1 shows an embodiment of an inkjet recording apparatus according to the present invention. In the figure, 1 is an inkjet recording device, and this inkjet recording device 1 is
An ink storage part 2 that stores ink I, a needle-shaped recording electrode 3 disposed in the ink I in the ink storage part 2, and an ultrasonic vibration means 4 that applies ultrasonic vibration to the recording electrode 3. In the recording head 5 on the right, a voltage is applied between the recording electrode 3 and the counter electrode 6 according to the image information, such as the counter electrode i6 disposed at a position facing the ink storage portion 2 of the recording head 5). The main part thereof is constituted by a voltage application control means 7 for applying the voltage.

-F surface recording head 5, as shown in FIG. Ink I is stored inside the ink storage portion 2 . The ink storage section 2 includes an ink supply pipe 8
The pressure inside the ink tank 9 is adjusted to a predetermined pressure by a pressure regulator 10. Then, the ink I adjusted to a predetermined pressure from the ink tank 9 is supplied to the ink storage section 2 via the ink supply pipe 8, and the ink storage section 2
As shown in FIG. 2, the ink (2) is always accommodated at a constant depth d. Therefore, the ink ■ in the ink container 2 is detected by a liquid level gauge using a laser beam (not shown), and the ink I at a constant depth d is always stored in the ink container 2. .

Note that the ink depth d is set to, for example, 1 mm, but is not limited to this.

Further, as shown in FIG. 2, the bottom wall 11 of the ink storage section 2 is provided with a small insertion hole 12 in the center thereof through which the needle-shaped recording electrode 3 is inserted. teeth,
The ink C is placed in the ink I in the ink storage section 2 through the insertion hole 12.

The recording electrode 3 is, for example, a gold-plated tungsten wire with a diameter of 80 μm and a length of about 3 mm.
The diameter and width of the recording electrode 3 are not limited to those described above; for example, the diameter may be about 60 to 200 μm. The diameter of the insertion hole 12 is set to be slightly larger than the thickness of the recording electrode 3.

In the portion 3a of the recording electrode 3 located in the insertion hole 12,
A liquid-repellent treatment is applied by baking a material with high surface tension such as a silicone-based resin or a resin-based resin, and the insertion hole 12 is repelled by the area 3a of the recording electrode lA13 that has been subjected to the liquid-repellent treatment. This prevents inter from leaking from 1j-shi. Further, the tip of the recording electrode 3 is arranged so as to protrude by at least δ from the free surface 13 of the ink in the ink container 2, and the recording electrode 3 is exposed to ultrasonic waves by the ultrasonic vibration means 4. When the voltage is applied, ink I is applied to the tip of the recording electrode 3, as shown in FIG.
A convex mascout 14 is formed. The protrusion amount δ of the recording electrode 3 is set to, for example, 40 μm.

Further, the lower end of the recording electrode 3 is fixed to an ultrasonic excitation means 4. This ultrasonic excitation means 4 includes an 8!1 layer type piezoelectric vibrator 15. As shown in FIG. 4 and FIG.
The electrodes 17.18 sandwiching the piezoelectric cord 16 are stacked together with the electrodes 17.18 sandwiched between the piezoelectric cords 16 and the upper electrodes 17.17. The lower electrodes 18, 18... are connected to each other.

Then, by applying a high frequency voltage by the high frequency power supply 20 between the upper electrodes 17, 17, and the lower electrodes 18, 18, the piezoelectric elements 16, 16, . . .
It is designed to generate ultrasonic vibrations. At this time, each piezoelectric element 16, 16... is set to vibrate in the same direction, and each piezoelectric element 16, 16...
The vibrations of ・ are superimposed to obtain a large amplitude. The high frequency N source 20 has a frequency of, for example, 100 KHz.
, the input energy is set to 2W.

As shown in FIG.
The recording mold tii3 is vertically fixed to the upper end surface of the vibration plate 21 by brazing 22 or the like.

As shown in FIG. 1, the recording head 5, which is composed of the ink storage section 2, the recording electrode 3, and the ultrasonic vibration means 4 as described above, is mounted and fixed on a head moving table 23. The head moving table 23 is slidable in a direction perpendicular to the drawing via a moving shaft 24.24. The ultrasonic vibration means 14 is fixed to the head moving table 23 via a damper (not shown) so as not to propagate vibrations to the head moving table 23. Further, the ink storage section 2 is fixed on the head moving table 23 via a support means (not shown). During recording, the recording head 5 is driven together with the head moving table 23 by a driving means (not shown).

On the other hand, at a position facing the recording head 5, as shown in FIG. 1, a roll-shaped counter electrode 6, which also functions as a support surface for the recording sheet 25, is arranged with a predetermined gap therebetween. As this counter electrode 6, a metal roll made of stainless steel or the like having a diameter of 70 mm and a length of 320 mm, on which one recording sheet 25 of A4 size can be wound, is used, and the recording sheet is wound around the surface of this roll. 25 has sheet fixing rolls 26 and 27 at both ends.
It is tightly attached in a fixed state. As the recording sheet 25, for example, a synthetic paper coated with a sintered resin based on a polyethylene film is used. The counter electrode 6 is rotationally driven at a constant speed or intermittently by a drive motor or the like (not shown in FIG. 2).

Further, as shown in FIG. 1, a pulse voltage is applied between the recording electrode 3 and the counter electrode 6 according to image information by a voltage application control means 7. This pulse voltage is, for example, 3.0 KV.

Pulse width 200μsec, pulse repetition frequency 800t
-1z is used. As shown in FIG. 2, a lead wire from the voltage application control means 7 is connected to the vibration plate 21 to which the recording mold FF13 is fixed by soldering or the like.

Further, as the ink I stored in the ink storage section 2, for example, an oil-based pigment dispersion type ink I is used. The physical properties of the ink include, for example, a viscosity of 10 to 100.
A material having a surface tension of 0 mPa100O of 306 yne/cm and a volume resistivity of about 104 to 108 Ω·cm is used.

In the above configuration, the inkjet recording apparatus according to this embodiment records an image in the following manner. That is, ink (2) is supplied from the ink tank 9 to the inlet storage section 2 of the recording head 5 via the ink supply pipe 8. Next, with the recording sheet 25 wrapped around the counter electrode 6, the counter electrode 6 is driven to rotate. In this state, ultrasonic vibration is applied to the recording electrode 3 by the ultrasonic vibration excitation means 4, and the ink I is transported by the ultrasonic vibration to form a film of the ink 1 along the tip of the recording electrode 3. As shown in FIG. 3, a convex meniscus 14 of ink (3) is formed at the tip of the recording mold Ii3. Then, an electric field is formed between the recording electrode 3 and the counter electrode 6 by applying a pulse voltage between the recording electrode 3 and the counter electrode 6 according to the image information by the voltage application control means 7.

Since the ink I has conductivity, charge is injected from the recording electrode 3 to the surface of the ink 91, but since the meniscus 14 of the ink I has a convex shape, the convex ink meniscus 14 The electric field is concentrated at the tip. Therefore, even when the distance between the recording electrode 3 and the counter electrode 6 is relatively large, the electric field can be efficiently concentrated. Then, since the attraction force due to the above concentrated electric field acts on the ink I, the ink I
is sucked toward the counter electrode 6 side by the Coulomb horn, and a force in the pullback direction due to the surface horn 1 contact with the surface 4291 in the ink storage portion 2 acts on the ink meniscus 14, so that the sixth As shown in the figure, the thread becomes thinner towards the tip.

The thin ink thread 30 that has grown in this way reaches the recording sheets 1 to 25, as shown in FIG.
This results in the formation of ink drums j~31 on the surface of. The ink dots 31 adhering to the surface of the recording sheet 25 are fixed on the recording sheets 1-25 by permeation into the recording sheets 1-25 and evaporation of the solvent into the surrounding air.

On the other hand, when an image is not recorded, no voltage is applied between the recording electrode 3 and the counter electrode 6, so that the electrostatic attraction does not act on the ink (2).

Furthermore, when the voltage application between the recording electrode 3 and the counter electrode 6 is finished, the Coulomb force acting on the ink (2) disappears, the ink dots 315 penetrate into the recording sheet 25, and the recording head 5
J: The thread 30 starts to return due to the surface tension of the ink (2) in the ink storage portion 2. Then, the ink string 30 becomes thinner and is finally cut off at the thinnest point.

The ink I discharged from the ink accommodating part 2 of the recording head 5 flows into the ink accommodating part 2 due to the surface tension of the ink accommodating part 2.
Return to At that time, the recording head 5 is
．． A predetermined number of signals are sent via 24.

In this way, ultrasonic vibration is applied to the recording electrode 3 disposed in the ink I in the ink storage section 2 by the ultrasonic vibration excitation means 4, and a convex meniscus 14 of the ink I is formed at the tip of the recording electrode 3. Since the recording electrode 3 is
When a voltage is applied to the ink, the electric field acts intensively on the ink meniscus 14, and the ink string 30 can be reliably grown toward the counter electrode. Therefore, the distance between the recording head 5 and the counter electrode 6 can be increased, and the recording sheet 2
In addition to easily adapting to changes in the thickness of the drum 31, it is also possible to print on a small drum 31 due to the effect of electric field concentration.

Since the inkjet recording apparatus according to this embodiment forms the convex ink meniscus 14 to cause the ink I to fly as described above, it is possible to form a thin ink string 30 and also to record. Gradation can be expressed by changing the width of the pulse voltage applied between the electrode 3 and the counter electrode 6 (pulse width modulation), as shown in FIG. FIG. 8 shows the change in dot diameter 31 when the width of the pulse voltage is changed. In this way, the small dots 31 to 140 μm with a diameter of about 10 μm are
It is possible to record even large dots exceeding m with extremely stable C. Therefore, it is fully applicable to color prune printers and video printers that use three to four-color inkjet recording devices to create original plates for printing presses (2).
Image quality is obtained.

[Effects of the Invention] The present invention has the above-described configuration and operation, and by reliably and stably forming a convex ink meniscus7, it is possible to increase the distance between the recording head and the opposing electrode, thereby improving the recording performance. It is possible to provide an inkjet recording device that can easily respond to changes in paper thickness, etc., and can also easily print small dots and express gradation.

An inkjet recording device capable of recording high-quality images can be provided.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of an inkjet recording device according to the present invention, FIG. 2 is an enlarged sectional view of the same essential part, and FIG. 3 is a sectional view showing a state in which ultrasonic vibration is applied to the recording electrode.
Figures 4 and 5 are cross-sectional views and exploded perspective views, not showing the ultrasonic excitation means, Figure 6 is a cross-sectional view showing the operation of the device in Figure 2, and Figure 7 shows the pulse width of the pulse voltage. FIG. 8 is a graph showing the relationship between pulse width and ink dot diameter, and FIG. 9 is a cross-sectional view of a conventional ink jet recording apparatus. [Explanation of symbols] 1... Inkjet recording device 8 2... Ink storage section 3... Recording electrode 4... Ultrasonic vibration excitation means 5... UD recording head 6... Counter electrode 7. ... Voltage application control means patent Applicant: Fuji Xerox Co., Ltd. Agent: Patent attorney: Satoshi I! 7 (1 other person) 4th figure

Claims (2)

[Claims] (1) a recording head having an ink storage section that stores ink, a needle-shaped recording electrode disposed in the ink in the ink storage section, and an ultrasonic vibration means that applies ultrasonic vibration to the recording electrode; , comprising a counter electrode disposed at a position facing the ink storage portion of the recording head, and a voltage application control means for applying a voltage between the recording electrode and the counter electrode according to image information. Features of inkjet recording device. (2) Using the inkjet recording apparatus according to claim 1, applying ultrasonic vibration to the recording electrode by the ultrasonic vibration means to form a convex meniscus of ink at the tip of the recording electrode; By applying a voltage between the recording electrode and the counter electrode according to the image information by the voltage application control means, the ink in the convex meniscus is ejected toward the counter electrode and onto the recording sheet disposed on the surface of the counter electrode. An inkjet recording method characterized by recording an image on.