JPS61127357A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To raise the density of picture element arrangement by avoiding the occurrence of blinding of ink by a method in which a recording paper is set on the back electrode, a recording signal voltage is applied between the back electrode and a stylus electrode, and ink in many openings of an ink sheet is selectively flied onto the recording paper by static electricity for recording. CONSTITUTION:Many openings 5 of a size of 5-200mum, formed in an ink sheet 4, are filled with liquid ink 6. The ink sheet 4 is moved to and lapped on a stylus electrode 3. The ink sheet 4 and a recording paper 2 are set with a spacing of some distance, e.g., at an interval of about 0.5mm. When a recording signal voltage is sent out from a recording signal circuit 7b for example, a strong voltage gradient is formed between the stylus electrode 3b and a back electrode 1, and the ink in the openings 5 of the ink sheet becomes charged with charge from the electrode 3b. The charged ink 6a is flied toward the direction of arrow along the electric force line toward the electrode 1, and recording is made on the paper 2. The liquid ink 6 should have an adequate conductivity.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention supplies liquid ink to a recording area using an ink sheet having a large number of openings, and in the recording area, the liquid ink in the large number of openings is removed by electrostatic force. The present invention relates to an inkjet recording apparatus that selectively performs recording by ejecting ink onto a recording paper surface.

[Technical background of the invention and its problems]

In recent years, various recording methods have been proposed for recording various types of information such as a single character image on recording paper. Among these, the inkjet recording method allows liquid ink to be ejected onto the surface of the recording paper, and can produce clear monochrome or color recorded images.On the other hand, the conventional inkjet recording method ejects liquid ink from a micro-diameter nozzle. Since it is configured to eject water, there is a problem in that the nozzle is easily clogged.

Therefore, in Japanese Patent Application No. 58-178201, an inkjet type recording apparatus, which is not the nozzle type, was proposed. This involves forming a large number of minute holes or recesses (hereinafter referred to as openings) in the film, and transporting each opening of the film filled with liquid ink to the thermal head section to bring the film into contact with the thermal head. Recording in which the thermal head is heated by a recording signal applied to the thermal head to generate bubbles at the interface between the thermal head and the ink side, and the pressure of the generated bubbles causes the ink in the mouth to face the thermal head. It records by ejecting it onto the paper.

This recording apparatus has the advantage that it is less prone to clogging than the nozzle type inkjet recording method. However, in this recording device, the liquid ink in the opening adjacent to the area heated and ejected by the thermal head is heated and hardened by the adjacent thermal head, and the thermal head facing the opening is activated by the recording signal. There is a risk that it will not be possible to eject from the opening when heated.

[Purpose of the invention]

The present invention has been made in view of these circumstances, and provides an ink composition that does not cause ink clogging, allows high-density bidirectional arrays, and is applicable.

It is an object of the present invention to provide an inkjet recording device with fewer restrictions on physical properties.

[Summary of the Invention] In order to achieve the above object, an inkjet recording device according to the present invention transports liquid ink to a recording site, controls the size of ink particles, and effectively applies an electrostatic field to the ink. Using an ink sheet provided with an opening to allow the stylus electrode to contact the ink sheet at a recording site, a back electrode is provided at a position facing away from the ink sheet, and a recording paper is placed on the back electrode,
A recording signal voltage is applied between the back electrode and the stylus electrode, and the ink in the many openings of the ink sheet is selectively ejected onto the recording paper surface by electrostatic force for recording.

[Embodiments of the invention]

Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a schematic sectional view showing a first embodiment of the device of the present invention. In this figure, 1 is the back electrode, 2 is the recording paper, and 3 is the back electrode.
(a-d) are stylus electrodes, 4 is an ink sheet, 5 is an opening in the ink sheet, 6 is liquid ink filled in the opening 5, 5a is ink in flight, 7 (a-d) are each stylus electrode This is the recording signal circuit connected to. Although the stylus electrode may be used alone, in the illustrated example, a plurality of stylus electrodes are assembled to form a multi-stylus electrode. The ink sheet 4 is made of plastic or metal sheet with a thickness of about 10 to 100 μm by means of laser beam processing, photo etching, electric discharge machining, etc.
A device having a large number of openings (holes, recesses) 5 of approximately 200 μm size is well applied, and the openings 5 are filled with liquid ink 6 and transferred to the stylus electrode 3. Then overlap it with the electrode 3.

The distance between the ink sheet 4 and the recording paper 2 is a certain distance, for example 0.
．． They are arranged at intervals of about 5 intervals. When a recording signal voltage is generated from the recording signal circuit, for example 7b, the stylus electrode 3b
A strong potential gradient is formed between the ink sheet openings 5 and the back electrode 1, and charges are injected into the ink filling the ink sheet openings 5 from the stylus electrode 3b, and the ink becomes charged. The charged ink 6a flies in the direction of the arrow along the lines of electric force toward the back electrode 1, and is recorded on the recording paper 2.

Therefore, the liquid ink 6 needs to have appropriate conductivity. If the conductivity is too low, charge injection from the stylus electrode 3 will be insufficient and it will be difficult to generate ink flying force.On the other hand, if the conductivity is too high, the ink 6 around the stylus electrode 3 will be However, a large amount of charge is injected into the recording dot, causing the ink 6 to fly even from the portion of the ink sheet 4 outside the area in contact with the stylus electrode 3, resulting in a significant enlargement of the recording dot diameter. An electrical short occurs between the styli, resulting in a drop in signal voltage or a crosstalk condition. A preferable ink conductivity value in order to prevent such problems from occurring is a value of IX107Ω-crn to lXl0''Ω-σ.

One of the characteristics of the supply of ink 6 by the ink sheet 4 is that there is no ink supply source other than the ink 6 stored and filled in the sheet opening 5, so the size of the flying ink droplets is determined by the size of the ink sheet opening. It has the advantage that it is less susceptible to fluctuations in ink viscosity and conductivity, the voltage value and pulse width of the recording signal voltage, the bias voltage value, etc., and can perform recording with stable density.

On the other hand, the ink 6a is caused to fly when the electrostatic attraction force exerted on the charged ink 6 exceeds the ink adhesion force to the wall of the ink sheet opening 5 or the surface of the stylus electrode 3. Requires voltage application.

By constantly applying a bias voltage slightly lower than the threshold voltage between the stylus electrode 3 and the back electrode 1 and adding the recording signal voltage to the bias voltage, the recording signal voltage can be reduced to a small value. The recording response speed can be increased.

Furthermore, since the potential difference between the multi-stylus electrodes is reduced, leakage current is reduced, which has the effect of preventing a drop in recording signal voltage and occurrence of crosstalk.

FIG. 2 is a schematic sectional view of a second embodiment of the present invention, and this embodiment has a configuration in which a bias power source 8 is connected between the stylus electrode 3 and the back electrode 1. By applying a bias voltage, the ink 6 in the ink sheet opening S is injected with charge even when no recording signal voltage is applied, and at the same time, an electrostatic attraction force acts, causing the ink 6 to open in a meniscus shape as shown by reference numeral 9. It takes on a raised shape from 5. Therefore, lines of electric force are concentrated at a higher density at the tip of the ink 6, and when a recording signal voltage is applied, the ink 6 can be ejected more reliably and at a higher speed.

FIGS. 3A and 3B are explanatory diagrams schematically explaining the principle of ink flying in the recording apparatus of the present invention. The symbols in the figure correspond to those in FIG. The broken lines indicate the state of the equipotential lines at the moment when the recording signal voltage is applied.

The equipotential line is roughly formed to surround the stylus electrode 3b to which a signal voltage is applied, and charges of opposite polarity are induced in the back electrode 1 and the tip of the ink 6 in the ink sheet opening 5. The equipotential line is the stylus electrode 3b to which a signal voltage is applied.
are formed at a high density around the center, and therefore strong lines of electric force are formed between them. Furthermore, since the ink 6 in the ink sheet opening S acts as a conductor and has a convex shape rising from the surface of the stylus electrode 3b, equipotential lines are formed around each ink 6, and the Stronger lines of electric force act on the tip.

The ink 6 in the portion of the stylus electrode 3b to which the signal voltage is applied forms a meniscus-like bulge due to electrostatic force as shown in FIG. 3(B), and as a result, the electric lines of force act more strongly on the tip of the ink 6. It turns out. When the electrostatic attraction force acting on the ink 6 overcomes the adhesion force of the ink 6 to the wall of the opening 5 and the surface of the stylus pole 3b, the ink 6 starts flying and is formed toward the back electrode 1. It flies along the electric lines of force. As shown in FIG. 2, constantly applying a bias voltage to the back electrode 1 and the stylus electrode 3b means that recording starts from the state shown in FIG. 3(B), and at least the state shown in FIG. The time required to change from state A) to state (B) can be reduced, which helps improve recording speed, and as explained earlier, in the case of a multi-stylus electrode configuration, the potential difference between adjacent stylus electrodes can be reduced. Various effects can be obtained based on the reduction in

In the present invention, liquid ink can be supplied to the ink sheet by any method. The ink sheet has a large number of minute openings, and since the thickness of the ink sheet and the diameter of the openings do not differ much, it is possible to easily store and fill the openings with liquid ink simply by bringing the liquid ink into contact with the ink sheet. It is possible.

FIG. 4 is a schematic cross-sectional view of a third embodiment of the recording apparatus of the present invention. This embodiment is configured as a serial dot printer. In this figure, reference numeral 11 is a back electrode that supports the recording paper 12 and forms an electric field, and 13 is a recording rad assembly, in which an ink sheet 15 is movably held in contact with a multi-stylus electrode head 14. Reference numeral 16 denotes an ink sheet supply roll, and 17 denotes an ink sheet take-up roll. The ink sheet supply roll 16 is arranged so as to be immersed in liquid ink 19 stored in an ink container 18. A recording signal circuit 20 and a bias voltage source 21 are connected to the multi-stylus head 14 . During recording, as shown in FIG. 4(A), while moving the rad assembly 13 toward recording in the direction of arrow X, the ink sheet 15 is simultaneously transported in the X direction, and the recording signal is transferred to the multi-stylus. is applied to the electrode head 14. Recording for one line is completed by moving the rear assembly 13 toward the right in FIG. 4(A) to the end of the 12th surface of the recording paper. Next, as shown in FIG. 4(B), since the multi-stylus electrode head 15 is returned to the left end in the direction of arrow Y, the ink sheet 15 is rewound in the direction of X. During this time,
The recording paper 12 is moved for recording by one line in a direction perpendicular to the moving direction of the rad assembly 13, and preparation for recording the next line is completed.

In the present invention, various modifications can be made to the mechanism for moving the ink sheet, the mechanism for supplying ink to the ink sheet, the mechanism for relative movement between the recording head assembly and the recording paper, and the like. For example, if a multi-stylus head configuration is applied and the width of one multi-stylus stylus is long enough to cover the recording paper, it is possible to create a configuration in which only the ink sheet and the recording paper are moved during recording, resulting in extremely high performance. A speed recording device can be realized. Furthermore, for driving a multi-stylus head, it is possible to apply, for example, a matrix drive configuration.

〔Effect of the invention〕

As explained above, according to the present invention, the ink does not become clogged, the ink flies easily and stably, and recording can be ensured.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view according to the first embodiment of the present invention, FIG. 2 is a schematic cross-sectional view according to the second embodiment, FIG. 4(A) and 4(B) are schematic sectional views showing a third embodiment of the present invention. 1.11... Back electrode, 2,12... Recording paper,
3.14... Stylus electrode, 4.15... Ink" sheet, 5... Opening, 6,19.
...Liquid ink. Agent: Patent Attorney Susumu Ito, 2)2
．． - 5. Figure 1 Figure 2 Figure 3 (A) (B)
Figure 4

Claims (1)

[Claims] A stylus electrode and a back electrode are arranged apart from each other to hold a recording paper on the back electrode, while a recording paper is held on the stylus electrode.
An ink sheet having a large number of minute openings filled with liquid ink is supplied, and a recording signal voltage is applied between a stylus electrode and a back electrode to cause the ink in the openings of the ink sheet to fly onto recording paper for recording. An inkjet recording device characterized by: