JPH0550604A - Ink jet recording device - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a charge control type ink jet recording apparatus, and particularly to an apparatus for reducing deflection due to Coulomb force between charged ink droplets. And to provide a device for ejecting ink drops to a distance. [Structure] On the path of the ink droplet 2 discharged from the nozzle 1,
In addition to the charging electrode 3 and the deflection electrode 5, two or more electrodes are arranged,
First, the electrode closest to the nozzle 1 is charged with the different polarity from the ink droplet 2 to attract the ink droplet 2, and later the electrode next closest to the nozzle 1 is charged with the different polarity from the ink droplet 2 to attract the ink droplet 2. It is achieved by providing the accelerator 4 for the ink drop 2 configured as described above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge control type ink jet recording apparatus.

[0002]

2. Description of the Related Art Correction of deflection due to Coulomb force between charged ink droplets is carried out by a method of correcting the charge amount at the time of charging in consideration of the influence of ink droplets before and after, as in JP-A-57-91276. As in Japanese Patent Laid-Open No. 59-16761, it is general to provide thinned ink droplets that are not charged between necessary ink droplets.

On the other hand, no device for ejecting ink droplets far away is found.

[0004]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a device for reducing deflection due to Coulomb forces between charged ink drops. And to provide a device for ejecting ink drops to a distance.

[0005]

The above-mentioned object is to provide two electrodes on the path of the ink droplets ejected from the nozzle, in addition to an electrode for charging the ink droplet to a predetermined voltage and an electrode for forming an electric field for deflecting the charged ink droplet. The above electrodes are arranged, first the electrode closest to the nozzle is charged with the opposite polarity to the ink droplet to attract the ink droplet, and later the electrode next next to the nozzle is charged with the opposite polarity to the ink droplet to attract the ink droplet. It is achieved by configuring as follows.

[0006]

[Function] Two or more electrodes are arranged on the path of the ink droplet ejected from the nozzle, the electrode closest to the nozzle is charged to the opposite polarity to the ink droplet first to attract the ink droplet, and then the ink droplet to the nozzle next. The adjacent electrode is charged with an opposite polarity to the ink droplet to attract the ink droplet, thereby accelerating the ink droplet. As a result, the distance between the ink droplets is widened and the deflection due to the Coulomb force acting between the ink droplets can be reduced.

Further, the accelerated ink droplet can fly farther than the non-accelerated ink droplet.

[0008]

FIG. 1 shows an embodiment of an ink jet recording apparatus equipped with the ink droplet accelerator of the present invention. In FIG. 1, the charging electrode 3, the accelerator 4, and the deflection electrode 5 are arranged in this order on the path of the ink 2 discharged from the nozzle 1. Further, a gutter 6 for collecting the ink droplets 2 not used for printing or drawing is provided at the tip of the deflection electrode 5. The position of the accelerator 4 is not provided between the nozzle 1 and the charging electrode 3 due to the principle of the charge control type inkjet recording apparatus, but if it is on the path of the ink 2 deflected by the deflection electrode 5, the deflection electrode 5 and the gutter 6 are provided. The ink droplets can be accelerated by providing the gaps or in the distance from the gutter 6. Next, the principle from the nozzle 1 to the deflection electrode 5 will be described with reference to FIGS. In FIG. 2, the ink 2 pressure-fed from the ink supply unit of the ink jet recording apparatus tends to become particles due to the surface tension when discharged from the small hole at the tip of the nozzle 1. An excitation voltage having an appropriate cycle is applied to a voltage element that converts the voltage vibrations incorporated in the nozzle 1 into mechanical vibrations to obtain ink droplets 2 having a uniform particle size and spacing. At this time, the excitation voltage and the period applied to the voltage element are limited by the shape of the nozzle 1 and the physical properties of the ink 2. A video in which a current having a strength corresponding to the size desired to be deflected by the deflection electrode 5 is synchronized with the charging electrode 3 provided at a position where the ink 2 ejected from the nozzle 1 becomes an ink droplet 2 is synchronized with the cycle for generating the droplet. When given as a signal, the video current flows from the charging electrode 3 through the electrostatic capacitance of the space to the column of the ink 2 and is charged in the ink droplet 2 generated immediately after. Since the ink droplet 2 is separated from the charging circuit formed by the charging electrode 3, the ink 2 and the nozzle 1, it is not charged from the charging electrode 3 thereafter. The speed of the ink droplet 2 is determined by the pressure from the ink supply unit and the shape of the nozzle 1.

In FIG. 3, in this example, the accelerator 4 is composed of eight pairs of electrodes facing each other from the accelerator electrodes 4a to 4h and a charge controller 7 of the accelerator for arbitrarily charging each electrode of the accelerator 4. It is preferable that the electrode of the accelerator 4 has a symmetrical shape about the path of the ink droplet 2 because the Coulomb force generated between the electrode and the ink droplet 2 does not deflect the ink droplet 2. Therefore, the electrodes may be cylindrical. Also, ink drop 2
Since the course of (1) spreads in a fan shape by the deflection electrode 5, if an accelerator 4 is provided behind the deflection electrode 5 to accelerate all ink droplets 2, the accelerator 4 has a large and complicated shape.

Now, the ink droplet 2 coming out from the charging electrode 3
In the state in which the accelerator 4 is not operated, a flies at the above-mentioned predetermined speed unless there is Coulomb force between the ink droplets 2, air resistance, and gravity. However, the accelerator electrode 4a is charged to a different polarity from the ink droplet 2a by the charge controller 7 of the accelerator and attracts the ink droplet 2a by the Coulomb attractive force. Since the attractive force is the work of giving acceleration to the substance, the ink droplet 2a is transferred to the accelerator electrode 4a.
Will be accelerated by. Accelerator electrodes 4b, 4c, 4d, 4e, 4f, 4 according to the progress of the ink drop 2a
When charged to g and 4h, the ink droplet 2a can be accelerated corresponding to the sum of the attractive forces received. However, ink drop 2
Since the accelerator electrode 4 which is located behind is decelerated the ink droplet 2, the charging of the accelerator electrode 4 is stopped so as not to decelerate, or the ink droplet 2 is charged with the same polarity as the ink droplet 2 to accelerate the ink droplet 2 by the Coulomb repulsive force. To work. Ink drop 2
b and the accelerator electrode 4b, the ink drop 2c and the accelerator electrode 4e,
The ink droplet 2d and the accelerator electrode 4h are in a state of exerting a Coulomb repulsive force. That is, when observing the accelerator 4 from one ink droplet 2, the accelerator electrode 4 in the traveling direction exerts a large number and strong attractive force, and the rear accelerator electrode 4 exerts a large number and strong repulsive force to accelerate the ink droplet 2. become.

In this example, the same accelerator electrode 4 is used, and it is set so that the ink droplets 2 pass through the electrodes at the same time. This is because each electrode can obtain the same Coulomb attractive force by starting the charging from the accelerator electrodes 4a to 4h with an equal time difference, which simplifies the control of the charging controller 7 of the accelerator and the prediction of the acceleration effect. is there. Therefore, the electrode spacing is made wider on the 4h side than on the 4a side. However, the charging time is inversely proportional to the speed of the ink droplet 2 passing through it, and is 4 h.
Shorten the side. When the accelerator electrode 4 is installed in this way, the accelerator 4 becomes large. Therefore, when the electrodes are to be equidistant or unequal in distance, the charging start timing and the charging are adjusted so as to comply with the above-described accelerator principle. You have to set the time.

The ink droplet 2 that has passed through the accelerator 4 is accelerated and at the same time, the distance between the adjacent ink droplets 2 is widened by an equal distance. This is because the Coulomb repulsive force acting between the adjacent ink droplets 2 makes the intervals of the ink droplets 2 separated from the nozzle 1 uniform because the charging amount at the charging electrode 3 is different. Of the ink droplets 2 is averaged to reduce the variation in the position due to the arrival time when the ink droplets 2 adhere to the printing object. Moreover, the Coulomb repulsive force acting between the adjacent ink droplets 2 is inversely proportional to the square of the interval, so that the Coulomb repulsive force after acceleration can be set small.

In FIG. 4, the deflection unit is composed of a pair of electrodes, a deflection electrode 5 and a deflection electrode 5a, which face each other, and applies a constant voltage. As a result, an electric field is generated between the deflection electrode 5 and the deflection electrode 5a. Therefore, when the charged ink droplet 2 flies between the deflection electrode 5 and the deflection electrode 5a, a deflection force corresponding to the charge amount is generated, and the ink droplet 2 is deflected to the position on the print target assumed when the ink droplet 2 is charged. Since the Coulomb repulsive force acting between the ink droplets 2 that has started to deflect changes each other's deflection amount, the ink droplets 2 are printed on the object to be printed more than when the Coulomb repulsive force described in FIG. There is a large variation in the position when it adheres to. However, as described above, the ink droplet 2 that has passed through the accelerator 4 is accelerated, and at the same time, the distance between the adjacent ink droplets 2 is widened by an equal distance. Moreover, the Coulomb repulsive force acting between the adjacent ink droplets 2 is inversely proportional to the square of the interval, so that the Coulomb repulsive force can be set small here as well, and the change in the deflection amount due to the Coulomb repulsive force acting between the ink droplets 2 can be reduced. ..

Further, the deflecting electrode 5a is installed parallel to the path of the ink droplet 2 before entering the deflecting portion, and the deflecting electrode 5 does not block the trajectory of the ink droplet 2 which is maximum deflected to the deflecting side of the ink droplet 2. And in close proximity to each other.

It should be noted that the deflection angle and the deflection amount when passing through the electric field of the same strength for the same length are inversely proportional to the speed ratio, as compared with the case where the ink droplet 2 is not accelerated by being accelerated. Since it becomes smaller, the electric field at the time of deflection is strengthened,
The electrodes should be long. Since the change in the deflection amount due to the Coulomb repulsive force acting between the ink droplets 2 can be reduced, it is possible to increase the electric field during deflection and give the ink droplets 2 a larger deflection amount.

However, when the accelerator 4 is installed behind the deflection electrode 5, the above-described effect of making the deflection accurate cannot be obtained.
However, it is possible to increase the deflection amount of the ink droplet 2 by causing the ink droplet 2 to fly far away.

Further, since thinning ink droplets forcibly and periodically inserted between the ink droplets 2 are unnecessary so that the Coulomb repulsive force acting between the ink droplets 2 contributing to printing is indirect.
Characters can be drawn quickly and precisely, and vaporization of the ink solution from the thinned ink droplets can be suppressed, resulting in good consumption efficiency.

[0018]

According to the present invention, ink droplets can be efficiently accelerated. As a result, it is possible to use an ink having physical properties in which it is difficult to obtain the initial velocity discharged from the nozzle. Characters can be drawn at a position far from the nozzle. You can draw big. And the like.

Further, since the distance between the ink droplets is widened, the variation in the distance between the ink droplets is averaged in a proportional manner to reduce the variation in the position when the ink droplet adheres to the printing object. In addition, the charging of the ink droplets and the electric field of the deflection electrode can be strengthened, so that characters and the like can be drawn large even at a position close to the deflection electrode.

Further, since thinned ink droplets are not required, it is possible to draw a fast and precise character and the like, vaporization of the ink solution is suppressed, and consumption efficiency is good. And the like.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a principle diagram of a charging unit of a charge control type inkjet recording device.

FIG. 3 is a principle diagram of an accelerator according to the present invention.

FIG. 4 is a principle diagram of a deflecting unit of a charge control type inkjet recording apparatus.

[Explanation of symbols]

1 ... Nozzle, 2 ... Ink / ink droplet, 3 ... Charging electrode, 4
... Accelerator, 5 ... Deflection electrode, 6 ... Gutter, 7 ... Accelerator charge controller.

Claims (1)

[Claims] 1. A path of an ink droplet discharged from a nozzle,
In addition to the electrodes that charge the ink droplets to a predetermined voltage and the electrodes that create an electric field that deflects the charged ink droplets, two or more electrodes are arranged, and the electrode closest to the nozzle is charged to the opposite polarity to the ink droplet first. An ink jet recording apparatus comprising: an ink droplet accelerator configured to attract an ink droplet, and subsequently charge an electrode next to a nozzle to a different polarity from the ink droplet to attract the ink droplet.