JPH11348254A - Printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure stabilized printing by disposing a mechanism for capturing scattering particles generated between a printer and a matter to be printed thereby preventing intrusion of scattering particles into the printer. SOLUTION: The cover 13 of a printer is provided with a collecting electrode 14 on the side of a matter 5 to be printed and a part of the cover 13 containing the collecting electrode 14 forms a wall face on the inside thereof. Since the cover 13 and the wall face are made of metal, the wall face is earthed. A high voltage voltage 12 is applied to the collecting electrode 14 and a field is generated on the periphery thereof. Scattering particles 18 arriving at the field are attracted to the collecting electrode 14 and captured particles 19 adhere to the surface thereof. Since a field is formed between the collecting electrode 14 and the wall face, the field has no effect on the flying region of an ink particle 10 even when the ink particle 10 passes through the vicinity of the collecting electrode 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for printing identification characters on the surface of a printing object, and more particularly to peripheral devices for an ink jet printer.

[0002]

2. Description of the Related Art Ink jet printers form particles of ink and fly it onto a printing object to form characters and the like. As a means for causing the ink to fly, a method of changing the particleized ink by electrostatic force, a method of applying a pressure fluctuation (fluctuation due to a boiling phenomenon of a solvent in a minute area or a change in volume due to a piezo element) to the ink and discharging the ink from a nozzle, There is. The above is called a charge control type, and the following is called an on-demand type.

A charge control type ink-jet printer creates charged ink particles by applying a charge while discharging ink under pressure from a nozzle to which vibration is applied, and the ink particles are directed by an electrostatic deflection system. Is controlled to record character information. The principle is shown in FIG.

The ink in the ink bottle 8 is supplied by a supply pump 7
Is suctioned and pressurized. The pressure is controlled by the pressure regulating valve 1. The pressure is adjusted to 0.28 MPa as an example of the pressure. The ink whose pressure is controlled is supplied to the nozzle 3.
The nozzle 3 is provided with an electrostrictive element 2, and by applying an electric signal to the electrostrictive element 2, vibration can be applied to the ink.

An example of an electric signal is a frequency of 68.2 kHz.
z200V is applied. A discharge port is provided at the tip of the nozzle. The diameter of the discharge port is, for example, 65 μm. The vibrated ink is ejected from the ejection port to form ink particles 10 in the charging electrode 4. At this time, a charge can be applied to the ink particles 10 formed by applying a voltage to the charging electrode 4. 200 V is applied as an example of the voltage.

The ink particles 10 discharged from the nozzle 3 pass between the deflection electrode 9 and the ground electrode 12. Deflection electrode 9
Is applied with a voltage. As an example, a voltage of 5.4 kV is applied. The ink particles 10 passing between the deflecting electrode 9 and the ground electrode 12 are deflected by the electric field generated between the two electrodes and fly to the printing object 5 to form characters. The ink not involved in the characters is first stored in the gutter 11, and further collected by the collection pump 6 and returned to the ink container 8.

A feature of an ink jet printer is that ink is jetted for printing. Therefore, printing can be performed by separating the nozzle from the printing object, and printing can be performed on the uneven surface or the curved surface of the printing object. In addition, since the charge amount can be electrically changed, the character information can be easily changed. Taking advantage of these features, steel,
It is often printed on paper, aluminum, plastic, glass, etc. Conventionally, methyl ethyl ketone, methanol, or ethanol has been mainly used as a solvent in order to use a resin having an adhesive force for these materials as a material of the ink.

[0008] Water is sometimes used as a solvent for printing on printed matter or food that does not require strong adhesive force. In particular, in order to reduce the influence on the working environment, the main solvent tends to shift from methyl ethyl ketone to ethanol and water. In addition, dyes that impart color to the ink include dyes that dissolve in these solvents and pigments that dissolve in the medium without dissolving in the medium. Conventionally, dyes having a metal such as chromium have been mainly used because they are soluble in a medium and have excellent light resistance. However, it becomes difficult to use chromium or the like due to environmental issues, and pigments having excellent light resistance tend to be used instead.

Since these solvents all have a certain amount of vapor pressure at atmospheric pressure, they are ejected from the nozzle 3 as ink particles 10 as shown in FIG. When it comes into contact with the atmosphere while it is being recovered, part of it is volatilized into the atmosphere as vapor. As a result, the composition ratio of the solvent in the recovered ink decreases from the initial state. Therefore, the ink concentration and the ink viscosity increase. When the ink jet printer discharges from the nozzle 3 as described above, the ink is deformed by the vibration applied from the electrostrictive element 2 to form the ink particles 10.

Therefore, when the viscosity of the ink increases,
In some cases, the deformation of the ink is hindered and the formation of the ink particles 10 due to the vibration applied from the electrostrictive element 2 is not performed quickly. In order to prevent this, it has a function of replenishing the solvent volatilized by a mechanism not shown in the figure.
Therefore, a liquid level sensor for managing the liquid level of the ink is provided.

[0011]

The velocity of the ink particles 10 discharged from the nozzle 3 is, for example, about 10 m / s. When the ink particles 10 reach the print target 5 at this speed, all the ink of the ink particles 10
May not adhere to the surface. This state is shown in FIG.
That is, when the ink particles 10 reach the surface of the printed matter 5, the shape of the particles may be deformed, and a part thereof may be repelled and repelled from the printed matter as flying particles 18. For example, when the print target 5 is made of a non-liquid absorbing material, the ink of the ink particles 10 that has reached the surface of the print target 5 is not absorbed by the print target 5 but is reflected by the surface of the print target 5. There is a case. Further, when the printing density of the ink particles 10 on the surface of the printing object 5 is high, the other ink particles 10 are added to the ink which has already reached the surface of the printing object 5 but is in an undried state at the above speed. It will collide.

Therefore, a part of the ink solution is scattered and scattered particles 18 are formed. Further, the printing object 5
In the case of a material that is easily charged or has poor conductivity, the ink particles 10 reach the surface of the printing object 5 and the charges held by the ink particles 10 stay on the surface of the printing object 5. It will be. Then, the other ink particles 10 and the electric charges on the surface of the printing object repel each other, so that more scattered particles 18 are formed.

In many cases, the electric charge on the surface of the printing object 5 is grounded due to the conductivity of the moisture adsorbed on the surface of the printing object 5. However, when the atmosphere is dry and the humidity is low, this adsorbed moisture also decreases, so that surface conductivity cannot be obtained,
This makes it easier for electric charges to remain on the surface of the printing object 5.

These scattered particles 18 are supposed to be
Is a part of the ink that should be at the predetermined position, but may scatter and reach a place other than the target position on the printing target 5. Therefore, the surface of the printing object 5 is stained. When the scattered particles 18 scatter to the printing device side, they may enter the printing device. In this case, since the deflecting electrode 9 in the printing apparatus has a high voltage of 5.4 KV, the scattered particles 18 are attracted to the deflecting electrode 9 and become contaminated particles 20 that stain the deflecting electrode 9, and adhere to the surface of the deflecting electrode 9. I do. If this amount increases,
In some cases, current flows through a circuit other than a predetermined circuit via the attached ink. For example, when ink adheres between the deflection electrode 9 and the ground electrode 12, the current of the deflection electrode 9 flows to the ground electrode 12 via the ink. As a result, the voltage of the deflection electrode 9 cannot be maintained, and the function as a printing device cannot be performed.

Therefore, when the scattered particles 18 are generated,
It is necessary to prevent the flying particles 18 from entering the printing apparatus. One of the methods is to prevent the intrusion of the scattered particles 18 by sending atmospheric air into the printing apparatus and applying pressure. However, when the air is sent into the printing apparatus, the flow of the wind caused by the air may make the flying motion of the ink particles 10 contributing to the printing unstable, causing a problem such as a disturbance of the printing. Further, by increasing the distance between the printing device and the printing object 5, the scattering particles 18 are increased.
Can also be reduced.

However, as the distance from the print object 5 increases, the ink particles 10 contributing to printing receive more air resistance until the ink particles 10 reach the surface of the print object 5. May be deviated from the preferred printing position, and a problem that the shape of the printed character changes may occur.

Further, it is also possible to send the atmosphere from the outside of the printing apparatus to the surface of the printing object and remove the flying particles by this flow. However, in this mechanism, since the scattered particles are further scattered, there is a problem in that the scattered particles are re-adhered to the surface of the printing object and contaminated.

An object of the present invention is to provide a method for preventing the occurrence of scattering which occurs when ink particles reach a printing object without supplying air which may disturb printing and without keeping a distance from the printing object. It is an object of the present invention to provide a printing device that performs stable printing by preventing particles from entering a printing device, and that prevents the scattering particles from adhering to the surface of a printing object and does not contaminate the surface of the printing object. .

[0019]

The object is achieved by providing a mechanism for collecting scattered particles generated between a printing apparatus and a printing object. As the collecting mechanism, vacuum suction or the like can be used. However, in vacuum suction, it is necessary to reduce the generation of vacuum. Therefore, a collecting mechanism using an electric field is effective for reducing the size of the apparatus.

That is, in FIG.
The collection electrode 14 is provided on the side of the third print object 5.
A high voltage 21 is applied to the collecting electrode 14. As an example, this voltage is 5 kV. The ink particles 10 ejected from the nozzle 3 reach the printing object 5, and a part of the ink particles 10 are scattered particles 18 and repel from the printing object 5. When the scattered particles 18 fly toward the cover 13 of the printing apparatus,
It is attracted by the electric field of the collecting electrode 14 and is captured as the capturing particles 19. Thereby, the scattering particles can be prevented from reaching the deflection electrode 9.

Since the high voltage 21 is applied to the collecting electrode 14, even when the ink particles 10 pass near the collecting electrode 14, it is expected that the electric field formed by the collecting electrode 14 will be affected. Therefore, it is necessary that the structure does not affect the electric field. Part of the cover 13 in which the collecting electrode 14 is housed forms a wall surface A15 inside the collecting electrode 14. This cover 13 and wall A1
Material 5 is metal. The cover 13 and its wall A15 are grounded. As described above, the collecting electrode 1
Although a high voltage 21 is applied to 4, an electric field is formed between the collection electrode 14 and the wall A <b> 15 because the inner wall A <b> 15 is grounded. As a result, the ink particles 1
It is possible to prevent the electric field from affecting the area where 0 flies.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIG. 2 is a diagram showing the principle of a charge control type ink jet printer. FIG. 1 is a diagram showing a structure when the principle structure shown in FIG. 2 is incorporated in a printing apparatus.
The electrostrictive element 2, nozzle 3, charging electrode 4, deflection electrode 9, ground electrode 12, and gutter 11 shown in FIG. The cover 13 is made of metal and is grounded 22 by a circuit not shown. A collecting electrode 14 is provided on the cover 13 of the printing apparatus on the side of the printing object 5. Part of the cover 13 in which the collecting electrode 14 is housed forms a wall surface A15 inside the collecting electrode 14. The material of the cover 13 and the wall surface A15 is metal. Therefore, the wall surface A15 is also grounded. A high voltage 21 is applied to the collecting electrode 14.

In FIG. 2, the ink in the ink container 8 is suction-pressed by the supply pump 7. The pressure is the pressure regulator 1
Is controlled by The pressure is adjusted to 0.28 Mpa as an example of the pressure. The ink whose pressure is controlled is supplied to the nozzle 3. The nozzle 3 is provided with an electrostrictive element 2, and by applying an electric signal to the electrostrictive element 2, vibration can be applied to the ink. A frequency of 68.2 kHz 200 V is applied as an example of the electric signal. A discharge port is provided at the tip of the nozzle. The diameter of the discharge port is 65 as an example.
μm. The vibrated ink is ejected from the ejection port to form ink particles 10 in the charging electrode 4. At this time, a charge can be applied to the ink particles 10 formed by applying a voltage to the charging electrode 4. 200 V is applied as an example of the voltage.

The ink particles 10 discharged from the nozzle 3 pass between the deflection electrode 9 and the ground electrode 12. A voltage is applied to the deflection electrode 9. As an example, a voltage of 5.4 kV is applied. The ink particles 10 passing between the deflecting electrode 9 and the ground electrode 12 are deflected by the electric field between the two electrodes and fly to the printing object 5 to form characters. The ink not involved in the characters is first stored in the gutter 11, and further collected by the collection pump 6 and returned to the ink container 8.

The ink particles 10 discharged from the nozzle 3 reach the printing object 5, and a part of the ink particles 10 are scattered particles 18 and repel from the printing object 5. The repelled flying particles 18 fly toward the cover 13. A collecting electrode 14 is provided on the cover 13, and a high voltage of 5 kV is applied to the collecting electrode 14 as an example. Therefore, an electric field is generated around the collecting electrode 14. The scattered particles 18 that have reached the electric field are deflected by the electric field, are attracted to the collecting electrode 14, become the collecting particles 19, and adhere to the surface of the collecting electrode 14.

On the other hand, the ink particles 10 are
Is also expected to be affected by the electric field formed by the collecting electrode 14. Therefore, it is necessary that the structure does not affect the electric field. Part of the cover 13 in which the collecting electrode 14 is housed forms a wall surface A15 inside the collecting electrode 14. Although the high voltage 21 is applied to the collecting electrode 14, the electric field is applied to the collecting electrode 14 because the inner wall A15 is grounded.
And the wall A15. As a result, it is possible to prevent the electric field from affecting the region where the ink particles 10 fly.

The ink is collected as collecting particles 19 on the collecting electrode 14. When the amount of adhesion increases, the voltage applied to the collection electrode 14 via the attached ink is changed to the wall A15.
Or the cover 13 may leak. Therefore, it is necessary to clean the collection electrode 14 to remove the collected ink before the leakage. To this end, it is effective that the collecting electrode 14 has a structure that is easy to clean. This can be achieved by making the collecting electrode 14 separable from the cover 13. FIG. 3 shows an example of the structure.

In FIG. 3, a cover B17 is provided between the cover 13 of the printing apparatus and the printing object 5. The collecting electrode 14 is provided inside the cover B17. A part of the cover B17 in which the collecting electrode 14 is housed forms a wall surface B16 inside the collecting electrode 14.
The material of the cover B17 and the wall surface B16 is metal.
The cover B17 is provided by means not shown in the drawing.
3 and physically and electrically. Therefore, the wall surface b is also grounded. A high voltage is applied to the collecting electrode 14 by a circuit not shown. The trapping principle in FIG. 3 is the same as that shown in FIG. The cover B <b> 17 shown in FIG. 3 can be separated from the cover 13. Therefore, when the collected particles 19 adhere to the collecting electrode 14, the cover B17 can be separated and washed. This facilitates the cleaning operation.

[0030]

According to the present invention, it is possible to prevent scattered particles from entering the printing apparatus, so that malfunction of the printing apparatus due to contamination of the scattered particles can be prevented. Further, since the scattered particles are collected, it is possible to prevent the scattered particles from reaching the surface of the printing object and contaminating the surface of the printing object.

[Brief description of the drawings]

FIG. 1 is a sectional view of a printing apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the principle of a printing apparatus according to one embodiment of the present invention.

FIG. 3 is a sectional view of a printing apparatus showing another embodiment of the present invention.

FIG. 4 is a cross-sectional view of a printing apparatus showing a conventional printing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pressure regulating valve, 2 ... Electrostrictive element, 3 ... Nozzle, 4 ... Charging electrode, 5 ... Printed object, 6 ... Recovery pump, 7 ... Supply pump,
8 ink bottle, 9 deflection electrode, 10 ink particles,
11: gutter, 12: ground electrode, 13: cover, 14 ...
Collection electrode, 15: Wall A, 16: Wall B, 17: Cover B, 18: Scattered particles, 19: Collection particles, 20: Contaminated particles, 21: High voltage, 22, 23: Ground.

Claims (5)

[Claims] 1. A printing apparatus having a function of catching fine particles between a printing apparatus and a printing object. 2. A printing apparatus according to claim 1, wherein said printing apparatus is a printing apparatus for printing on a printing object by ink particles formed by discharging ink from nozzles. 3. A printing apparatus for printing on an object to be printed with ink particles formed by discharging the ink according to claim 2 from a nozzle, wherein the printing apparatus always discharges ink from the nozzle and collects ink particles not used for printing. A printing device for discharging the collected ink again. 4. The printing apparatus according to claim 1, wherein the function of capturing the fine particles is a function of capturing by an electric field. 5. The printing apparatus according to claim 1, wherein a mechanism having a function of capturing fine particles can be separated from the printing apparatus.