JPH01200965A - Electrostatic recorder - Google Patents

Abstract

PURPOSE:To elevate jet efficiency and jetting positional accuracy of ink, by a method wherein a projection is formed around a nozzle, and an electric conductor is formed on a surface of this projection and an inner surface of the nozzle. CONSTITUTION:Ink jetting nozzles 3a are formed at certain intervals in a longitudinal direction of a nozzle plate 3, and a projection 3b is formed around each nozzle 3a. This nozzle plate 3 is connected to a slit state ink feed port 2 of a head part 1. Further, the surface of the projection 3b and the inner surface of the nozzle 3a are processed by plating or printing to form an electric conductor (electrode) part 30, and each electric conductor 30 is connected to a recording signal driving circuit 4. Voltage is impressed between the electric conductor 30 and a counter electrode 5 to form an electric field. Ink is attraoted to an ink counter electrode 5 side by injecting electric charge to an ink meniscus of the nozzle 3a to print a recording paper 6 positioned in front of the electrode 5. In that case, ink discharging force can be increased by the projection 3a around the nozzle 3a and the electric conductor treatment 3c processed on said surface, and jet efficiency and jetting positional accuracy can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic attraction type recording device, and more particularly to a head portion of an electrostatic attraction type recording device.

PRIOR ART FIG. S is a perspective view showing an example of a conventional electrostatic inkjet recording device, in which 11 is an ink supply port formed in the shape of a slit, and 12a and 12b are the ink supply ports 11.
13 is a large number of electrodes arranged on the lower plate 12b, 14 is a back electrode arranged opposite to the supply port 11, and 15 is an electrode on the back electrode 14. The recording paper 16 that moves along the recording paper 16 is a driving power source that supplies a high voltage to selected electrodes of the electrodes 13.

In the electrostatic inkjet recording device, when ink is injected into the ink supply port 11, a continuous meniscus is formed in the ink supply port 11, and one or more selected electrodes 13 are supplied with a high voltage from the drive power source 16. is supplied, the selected l! Ink near the poles is pulled toward the back electrode 14, ejected from the ink supply port 11, and adheres to the recording paper 15 provided in front of the back electrode 14, thereby printing recorded information.

In the electrostatic inkjet recording device configured in this way, since the ink supply port 11 is slit-shaped, there is a misalignment between the back electrode position and the selected ejection position, and the ink supply port 11 is slit-shaped, so that the back electrode position and the selected ejection position are misaligned. It was impossible to jet the ink. In addition, since ink is selectively sucked from the continuous meniscus formed in the ink supply port 11,
There is a drawback that the jetting characteristics of the ink vary slightly due to changes in ink viscosity and surface tension, that is, changes over time and environmental temperature. Furthermore, when the slits are arranged in a full line, it is difficult to make the gaps between jets uniform, which causes variations in pixel diameter. Furthermore, in order to eject the ink, it is necessary to apply a high voltage to the electrodes 13 and 14 facing each other, which has the drawback of poor electrical-mechanical conversion efficiency and high operating costs.

Therefore, a vibrator is installed at the slit opening of the head to create unevenness on the ink liquid surface, which promotes the formation of an ink meniscus due to electrostatic force, shortens the meniscus formation process, and
It is known that the abbreviation was attempted (Japanese Patent Application Laid-Open No. 1975)
8-179663), in this case, it was difficult to tune the standing wave, and the wavelength also changed due to temperature changes.

In addition, by using the sudden change in pressure gradient caused by the bending of the air flow to stop the ejection of ink droplets,
This method stabilizes the flying state of ink droplets at high speed to obtain good images (Japanese Patent Laid-Open No. 57-1204).
(Refer to Publication No. 52), there was a problem that the device was complicated and the cost was high.

Therefore, the present applicant first developed a body that includes a body having an ink supply path in which a plurality of electrode conductors are arranged, and a nozzle plate in which a plurality of nozzles are integrally formed, and the opening of the ink supply path. proposed an electrostatic inkjet recording device in which the nozzle plate is joined so that the electrodes and nozzles correspond to each other.

FIG. 6 is a sectional view showing an example of an inkjet head of the electrostatic inkjet recording device previously proposed by the present applicant, and in the figure, reference numeral 17 denotes a nozzle plate on which a plurality of nozzles 18 are integrally formed. The nozzle plate 17 is joined to the opening of the ink supply port 11 so that each electrode 13 and nozzle 18 correspond to each other. F is the ink ejection force determined by the electric flux density A and the relative dielectric constant of the ink, ε,
is the dielectric constant of air, Gp is the recording electrode 13 and the back electrode 1
F is the inter-electrode distance between F and F, and is expressed by the following formula.

In this case, since the electrode 13 is arranged to overtake the nozzle plate 17 and the front surface of the electrode is covered with ink, there is a drawback that the ink ejection force F becomes small.

Purpose The present invention was made in view of the above-mentioned circumstances.
In particular, in inkjet recording devices that use electrostatic attraction to eject ink from an ejection port and adhere it to recording paper, we have further improved the nozzle plate, in which multiple nozzles are integrally formed, as described above. This was done to improve efficiency and injection position accuracy.

Structure In order to achieve the above-mentioned object, the present invention provides an electrostatic inkjet recording device that uses electrostatic attraction to eject ink from an ink ejection port and adheres it to recording paper, which includes a body having an ink supply path; and a nozzle plate formed with nozzles separated in the longitudinal direction, the nozzle plate is joined to the opening of the ink supply path of the body, and the periphery of each nozzle is protruded, and the protrusion A conductor is formed on the surface of the part and the inner surface of the nozzle, and the conductor is connected to a recording signal drive circuit. Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a main part configuration diagram for explaining an embodiment of an electrostatic inkjet recording apparatus according to the present invention, FIG. 2 is an enlarged cross-sectional view of the nozzle portion of FIG. 1, and FIG. An example of a nozzle plate used in the implementation is shown, (a) is a front view, (b) is a cross-sectional view of B-Bll in (a), and Fig. 4 is a comparison of injection efficiency with a conventional example. In the graph,
1 is a head part, 2 is an ink supply port formed in the shape of a slit, and 3 is a nozzle plate formed with nozzles 3a separated in the longitudinal direction, and a protrusion 3b formed around the nozzles 3a; The protrusion 3b is formed integrally with the nozzle 3a on the nozzle plate 3 by etching photosensitive glass or injection molding resin, and then,
The surface of the protrusion and the inside of the nozzle are plated or printed to form conductor (VjA) portions 3c, and each conductor portion 3c is connected to a recording signal calling circuit 4.

5 is a counter electrode, 6 is a recording paper, and the opposing electrode 30, 5
When a voltage is applied between, an electric field is formed and the nozzle 3
An electric charge is injected into the ink meniscus formed at a, the ink is pulled toward the counter electrode 5 in a spindle shape, and is printed on the recording paper 6 provided in front of the counter electrode 5.

According to the present invention, by forming a protrusion 3b around each nozzle 3a and further applying a conductive treatment 3c to the surface,
Since the inconvenience that the front surface of the electrode is covered with ink (ε2) is eliminated, the ink ejection force F increases. That is, if the relative dielectric constant of air ε1 = 1°, the specific dielectric constant of ink ε2 = 10°, the conventional ink ejection force = F1°, the ink ejection force according to the present invention = F2, then the ink ejection force increases by about 10%. However, in reality, the protruding electrodes shorten the distance between the electrodes and increase the area of the electrodes, resulting in a much higher efficiency.

Figure 4 shows the experimental results when the present invention and the prior art were actually tested.Curve A is the experimental result when the present invention was applied, and curve B is the experimental result when the conventional technology was used. When a constant voltage was applied to the electrode, the distance between the electrodes (Gp) was, for example, 2 kV, and the result was that the distance was 4 to 5 times greater. That is, at the same distance between electrodes, the conventional 1
Ink can be ejected with an applied voltage of /4 to 115.

As is clear from the above description, according to the present invention, by forming a protrusion around the nozzle and applying conductive treatment to the surface of the protrusion, the injection efficiency can be improved and the total cost can be reduced. In addition, the injection position accuracy can be improved.

[Brief explanation of the drawing]

FIG. 1 is a main part configuration diagram for explaining an embodiment of an electrostatic inkjet recording apparatus according to the present invention, FIG. 2 is an enlarged cross-sectional view of the nozzle portion of FIG. 1, and FIG. FIG. 4 shows an example of a nozzle plate used in the implementation of the present invention, in which (a) is a front view, (b) is a sectional view taken along line B-B in (a), and FIG. 4 is an electrostatic inkjet according to the present invention. A graph showing a comparison of the jetting efficiency of the recording device with a conventional example; FIG. 5 is a perspective view showing an example of a conventional electrostatic inkjet recording device;
FIG. 6 is a sectional view showing another example of a conventional electrostatic inkjet recording device. DESCRIPTION OF SYMBOLS 1...Head part, 2...Ink supply port, 3...Nozzle plate, 3a...Nozzle, 3b...Protrusion, 3
c... Electrode portion, 4... Recording circuit, 5... Counter electrode, 6... Recording paper. 41 12 3Vkv Figure 5 Figure 6

Claims (1)

[Claims] 1. In an electrostatic inkjet recording device that uses electrostatic suction to eject ink from an ink ejection port and adhere it to recording paper, it has a body with an ink supply path and a nozzle separated in the longitudinal direction. a nozzle plate formed therein, the nozzle plate being joined to the opening of the ink supply path of the body, and protruding around each nozzle;
An electrostatic inkjet recording device characterized in that a conductor is formed on the surface of the protrusion and the inner surface of the nozzle, and the conductor is connected to a recording signal drive circuit.