JPH1148486A - Electrostatic recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a good image quality without requiring any extra mechanism for controlling the displacement of adhering position of liquid drop by an arrangement wherein the displacement of a liquid drop on a recording medium relative to the jetting position of liquid drop a coloring material falls within a specified diameter of the liquid drop of coloring material on the recording medium. SOLUTION: In an electrostatic recorder, a recording medium 4 is carried while being curved in the carrying direction through rotation of a drum-like attraction electrode 3. When an image signal 5 is inputted to a signal electrode 1a-1c arranged in the breadthwise direction of the attraction electrode 3, a liquid drop 2 of coloring material is jetted from the signal electrode 1a-1c by an electrostatic force toward the metallic attraction electrode 3 applied with a specified potential and adheres to the recording medium 4 on the outer circumference of the attraction electrode 3. A decision can be made that the image quality is high when the positional displacement of the coloring material falls within 20% of the drop diameter of the coloring material on the recording medium 4 and the interval of the signal electrodes 1a-1c is set at 169 μm or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic recording apparatus which discharges and sucks a charged color material droplet by electrostatic force and records it on a recording medium.

[0002]

2. Description of the Related Art A conventional electrostatic recording apparatus, as disclosed in, for example, Japanese Patent Application Laid-Open No. 56-42663, employs a large number of signal electrodes for recording image signals using a color material charged to a certain polarity. Is supplied, the charged color material droplets are discharged from the signal electrode by Coulomb force by applying a potential difference between the signal electrode and the suction electrode opposed thereto,
Further, the mechanism is attracted by the suction electrode by the Coulomb force and adheres to the recording medium.

However, in such an electrostatic recording apparatus, since the coloring material droplet has a true charge, a plurality of signal electrodes are generated by the Coulomb repulsion between the droplets when or after leaving the signal electrode tip. There has been a problem that the plurality of color material droplets ejected from the ink jet head repel each other and spread, and do not coincide with the distance between the signal electrodes when recorded on the recording medium.

In order to solve this problem, Japanese Patent Laid-Open No. 7-2
Japanese Patent No. 37296 proposes a technique in which a mechanism for neutralizing a color material droplet is arranged between a signal electrode and a recording medium.

[0005]

However, in the technique described in Japanese Patent Application Laid-Open No. Hei 7-237296,
Since the neutralization mechanism is provided, there is a problem that the structure becomes complicated and the cost of the apparatus increases.

In addition, since a high potential is required to apply kinetic energy to the color material droplets which flies to the recording medium through the neutralization mechanism, there is a problem that power consumption is increased.

Accordingly, the present invention provides a low-cost electrostatic recording method capable of reducing the amount of displacement of a color material droplet discharged from a signal electrode on a recording medium to such an extent that good image quality can be obtained. It is intended to provide a device.

Further, according to the present invention, the amount of displacement of the color material droplets discharged from the signal electrodes on the recording medium can be reduced to such an extent that good image quality can be obtained with low power consumption. An object of the present invention is to provide an electrostatic recording device.

[0009]

In order to solve this problem, an electrostatic recording apparatus according to the present invention is arranged so that charged color material droplets are discharged from a plurality of signal electrodes and sucked to a suction electrode. An electrostatic recording apparatus for adhering a color material droplet to a recording medium positioned on a suction electrode, wherein a displacement amount of a droplet position on the recording medium at an adhesion position with respect to a discharge position of the color material droplet is determined. The color material droplet is configured to be within 20% of the droplet diameter of the upper color material droplet. The signal electrodes can be arranged in the main scanning direction and the sub scanning direction.

In this electrostatic recording apparatus, the distance between the plurality of signal electrodes is separated by a predetermined distance or more, and the amount of displacement of the color material droplet can be within 20% of the droplet diameter. It is desirable that the interval between the signal electrodes is 169 μm or more.

Further, in this electrostatic recording apparatus, by supplying image signals to the plurality of signal electrodes at different timings, the displacement of the droplet position of the color material droplet is reduced to 20% of the droplet diameter.
Within. The supply interval of the image signal is 8.
Desirably, it is 45 μsec or more.

As a result, good image quality can be obtained with a low-cost electrostatic recording apparatus without separately providing a mechanism for controlling the positional displacement of the attached droplets. Also, good image quality can be obtained with low power consumption.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a color material droplet is sucked by discharging a charged color material droplet from a plurality of signal electrodes and sucking the color material droplet to a suction electrode. An electrostatic recording device that adheres to a recording medium located on an electrode, wherein a displacement of a droplet position on the recording medium at an adhesion position with respect to a discharge position of the coloring material droplet is a liquid of the coloring material droplet on the recording medium. This is an electrostatic recording device in which the droplet diameter is within 20%.

[0014] The invention described in claim 2 of the present invention provides:
An electrostatic recording apparatus according to claim 1, wherein the signal electrodes are arranged in a main scanning direction and a sub-scanning direction.

According to a third aspect of the present invention, in the first or the second aspect of the present invention, the distance between the plurality of signal electrodes is separated by a predetermined distance or more, so that the position of the color material droplet is reduced. This is an electrostatic recording apparatus in which the displacement is within 20% of the droplet diameter.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the distance between the plurality of signal electrodes is 16
This is an electrostatic image recording apparatus having a thickness of 9 μm or more.

According to a fifth aspect of the present invention, in the first or the second aspect of the present invention, the image signal is supplied to the plurality of signal electrodes at different timings, thereby displacing the droplet position of the color material droplet. This is an electrostatic recording apparatus in which the amount is within 20% of the droplet diameter.

According to a sixth aspect of the present invention, in the fifth aspect, the image signal supply interval is 8.45.
This is an electrostatic recording device that is set to be longer than μ second.

According to such an electrostatic recording apparatus, a good image quality can be obtained without increasing the cost of the apparatus by separately installing a mechanism for controlling the displacement of the attached droplets. It has the action of:

Further, since there is no need for power for neutralizing the charge of the color material and obtaining kinetic energy for causing the color material droplets to fly to the recording medium, good image quality can be obtained with low power consumption. Has the effect of being able to.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. In all the drawings for describing the embodiments, the same members will be denoted by the same reference numerals, and duplicate description will be omitted.

(Embodiment 1) FIG. 1 is a schematic view showing a head section of an electrostatic recording apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a side view of FIG. 1, and FIG. 3 is a graph showing characteristics of a color material droplet used in the electrostatic recording apparatus of FIG.

As shown in FIG. 1, in the present electrostatic recording apparatus, signal electrodes 1a, 1b, and 1c have signal electrode rows arranged in a row in the main scanning direction. Although a large number of signal electrodes are actually used, including the case of the second embodiment described later, here, for simplification of description and drawings,
Several are modeled.

Signal electrodes 1a, 1 from which color material droplets 2 are discharged
A metal suction electrode 3 to which a predetermined potential is applied is arranged in front of b and 1c. Then, the recording medium 4 as a sheet is sent while being curved in the transport direction by the rotation of the drum-shaped suction electrode 3. At this time, the signal electrodes 1a and 1a arranged in the width direction of the suction electrode where the recording medium 4 is located are arranged.
When the image signal 5 is input to the signal electrodes 1b and 1c,
Color material droplets 2 are discharged from a, 1b, and 1c by electrostatic force, fly toward suction electrode 3, and adhere to recording medium 4 on the outer periphery of suction electrode 3.

As shown in FIG. 2, the signal electrodes 1a, 1b,
1c are arranged apart from each other by intervals L1 and L2 such that the positional displacement amount of the color material droplet 2 becomes equal to or less than a predetermined range described later. Note that the electrode spacing may or may not be constant, and can be set freely as long as the amount of displacement of the color material droplet 2 is equal to or less than a predetermined level. Also,
By scanning the head as a so-called serial head, a high recording density may be obtained while increasing the electrode spacing.

FIG. 3 shows data obtained by measuring the relationship between the distance between droplets and the amount of displacement of the droplets in the color material droplets 2 used in the electrostatic recording apparatus for two types of color material droplets having different droplet diameters.
Shown in The measured color material droplet diameters are 90 μm and 15 μm
m.

Here, the distance between droplets means the distance between droplets immediately after the droplet is discharged from the signal electrode. In the present embodiment, the distance between the tip of the signal electrode and the surface of the recording medium is 1 mm, and the voltage is 1 kV.

As can be seen from FIG. 3, even if the distance between the droplets is the same, the displacement of the droplet position increases as the droplet diameter increases. The reason for this is that the amount of charge carried by the coloring material is a function of the droplet diameter, and as the droplet diameter increases, the charge amount of the coloring material droplet increases and the Coulomb repulsion increases. In other words, as the droplet diameter decreases, the charge amount of the colorant droplet decreases, and the Coulomb repulsion decreases.

Further, even for color material droplets having the same diameter, if the distance between the droplets becomes narrow, the displacement amount of the droplet position becomes large. This is because the repulsive force acting between the charges of the respective color material droplets increases as the distance between the droplets decreases.
In other words, if the distance between the droplets increases, the repulsive force decreases and the displacement of the droplet position decreases.

The present inventor has performed printing while changing various conditions based on this newly found relationship, and has created the invention disclosed herein.

In the first trial, in an electrostatic recording apparatus capable of producing a color material droplet having a diameter of 30 μm, a recording material having a diameter of 62 μm was used.
Zero signal electrodes were arranged in a line at a constant interval of 175 μm to form a single signal electrode line.

In this case, the position displacement amount of the pixel which is the color material droplet in the state of being transferred to the recording medium is 2 μm on average.
m and less than about 10% of the generated pixels. Therefore, the displacement level was no problem in image quality, and an accurate printing result could be obtained.

In the second trial, in an electrostatic recording apparatus capable of producing a color material droplet having a diameter of 30 μm, 15
Five signal electrodes were arranged in a line at a constant interval of 1.4 mm to form one signal electrode line.

In this case, the displacement of the colorant droplet is almost zero, and remains at a level having no problem in image quality.
Extremely accurate printing results could be obtained. Also,
The main scanning is performed at 62 μm / s, and the sub-scanning is performed 32 rotations per A4 sheet by a paper feed by a motor, whereby
It was possible to print about three images per minute at a resolution of 00 dpi, and to obtain an image faster and with better image quality than before.

In the third trial, signal electrodes were arranged at a constant interval of 42 μm in an electrostatic recording apparatus capable of producing a color material droplet having a diameter of 15 μm. In this case, the displacement amount of the colorant droplet was extremely large, on average, about 20 μm, which was larger than the colorant droplet to be generated, and the positional accuracy of the pixels was poor, and good image quality could not be obtained.

In the fourth trial, a diameter of 15 μm and a diameter of 90 μm were used.
In an electrostatic recording apparatus capable of producing two types of color material droplets of μm, signal electrodes were arranged in a so-called staggered arrangement at a constant interval of 85 μm.

In this case, the displacement amount of the 90 μm color material droplet was about 15 μm on average and about 17% of the droplet diameter, but the displacement amount of the 15 μm color material droplet was average. Was about 12 μm, which was about 80% of the droplet diameter, and good image quality as a whole could not be obtained.

In the fifth trial, a diameter of 15 μm and a diameter of 90 μm were used.
In an electrostatic recording apparatus capable of generating two kinds of color material droplets of μm, signal electrodes were arranged in a so-called staggered arrangement at a constant interval of 169 μm.

In this case, the displacement of a pixel in a 90 μm color material droplet is about 6 μm on average, which is about 7% of the droplet diameter, and the displacement of a 15 μm color material droplet is about 3 μm on average. And about 20% of the droplet diameter. Therefore, the displacement of the droplet position is 2 for both colorant droplets.
It was within 0%, and good image quality was obtained as a whole.

As described above, when the displacement amount of the droplet position is within 20% of the droplet diameter, good image quality can be recognized. For that purpose, the interval between the signal electrodes is desirably 169 μm or more. .

(Embodiment 2) FIG. 4 is a schematic view showing a head section of an electrostatic recording apparatus according to another embodiment 2 of the present invention, FIG. 5 is a side view of FIG. 4, and FIG. 5 is a time chart illustrating a timing of transmitting an image signal input to each electrode row of the electrostatic recording apparatus.

As shown in FIGS. 4 and 5, the electrostatic recording apparatus according to the second embodiment has first signal electrodes 1a, 1b, and 1c arranged in a row in the main scanning direction. It has a column A1, a second signal electrode column A2 composed of signal electrodes 1d, 1e and 1f, and a third signal electrode column A3 composed of signal electrodes 1g, 1h and 1i.
a to 1i are three-dimensionally arranged in the main scanning direction and the sub scanning direction.

The signal electrodes 1a, 1b, 1c, the signal electrodes 1d, 1e, 1f, the signal electrodes 1g, 1h, 1i
They are arranged apart from each other by intervals L1 and L2.
The second signal electrode array A2 is separated from the first signal electrode array A1 in the main scanning direction X by an interval S1 corresponding to a desired recording density.
However, the third signal electrode array A3 is separated from the second signal electrode array A2 in the main scanning direction X by an interval S2 corresponding to a desired recording density.
However, each of them is displaced in the plane direction. Further, the signal electrode rows A1, A2, and A3 are spaced apart from each other by intervals H1 and H2 corresponding to a desired recording density in the sub-scanning direction Z. Further, a signal electrode array following this may be arranged one after another. Note that the interval L
1, L2, S1, S2, H1, and H2 may or may not be constant to each other, and can be set freely if the positional displacement amount of the color material droplet 2 is equal to or less than a predetermined level. .
Also, the signal electrode rows may be arranged by the number that fills the signal electrode intervals so as to correspond to the desired recording density, or may be arranged by a number smaller than that to scan the head to fill the signal electrode intervals. .

Here, the image signals 5a, 5b and 5c are input to the signal electrode rows A1, A2 and A3, respectively.
As shown in FIG. 6, after the image signal 5a is applied to the first electrode array A1, a delay time t1 calculated from the speed after the discharge of the color material droplet 2 and the data of FIG. Thus, the image signal 5b is provided to the second signal electrode array A2. Similarly, the image signal 5c is applied to the third signal electrode array A3 with a delay of the delay time t1 + t2.

A trial based on the data shown in FIG. 3 was performed on the electrostatic recording apparatus having the above-described configuration.

That is, following the first embodiment, the sixth
In the trial, the signal electrode was 169 μm in an electrostatic recording apparatus capable of generating a color material droplet having a diameter of 30 μm.
The signal electrode rows arranged at intervals are 42 μm in the main scanning direction,
A plurality of layers were arranged with a space of 42 μm in the sub-scanning direction. In this configuration, the image signal 5a is transmitted to the first
, And image signals 5b and 5c were sequentially applied to the second and third signal electrode arrays A2 and A3 at intervals of 20 μsec.

As a result, in the main scanning direction, the displacement of the droplet position was about 5 μm on average and less than about 20% of the generated pixels, and no displacement occurred in the sub-scanning direction. Therefore, good image quality could be obtained at high speed in both the main and sub scanning directions.

According to this, different image signals 5a, 5a
When supplying b and 5c, good image quality can be obtained by adjusting the interval so that the Coulomb repulsion between the color material droplets is 20% or less of the displacement of the droplet position. However, the shorter the supply interval of the image signals 5a, 5b, 5c, the higher the printing speed. Therefore, it is not desirable to increase the interval unnecessarily.

Therefore, the present inventor has shortened the signal interval in the sixth trial from 20 μs to obtain the shortest image which satisfies 20% or less, which is the amount of displacement of the droplet position, at which good image quality can be obtained. In search of the signal supply interval, a value of 8.45 μs was obtained.

The supply timing of the image signal can be applied not only to the sub-scanning direction as in the present embodiment but also to the main scanning direction by using the apparatus of the first embodiment. . In this case, even if the distance between the signal electrodes is smaller than the above-described value, the displacement of the droplet position is 2
0% or less can be realized.

Therefore, in the present invention, it is sufficient that the supply interval of the image signals supplied to the plurality of signal electrodes at different timings is 8.45 μsec or more.

[0052]

As described above, according to the electrostatic recording apparatus of the present invention, the amount of displacement of the droplet position on the recording medium at the adhering position with respect to the discharge position of the color material droplet can be determined by the droplet diameter which has no problem in image quality. Of 20
By setting the ratio to within%, it is possible to obtain an effective effect that good image quality can be obtained without separately providing a mechanism for controlling the positional displacement of the attached droplet.

Thus, an effective effect that a low-cost electrostatic recording apparatus can be obtained can be obtained.

According to the electrostatic recording apparatus of the present invention,
Since there is no need for electric power to obtain kinetic energy to neutralize the charge of the color material and fly the color material droplet to the recording medium, an effective effect that good image quality can be obtained with low power consumption. Is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a head section of an electrostatic recording device according to a first embodiment of the present invention;

FIG. 2 is a side view of FIG. 1;

FIG. 3 is a graph showing characteristics of color material droplets used in the electrostatic recording apparatus of FIG. 1;

FIG. 4 is a schematic diagram showing a head section of an electrostatic recording device according to a second embodiment of the present invention;

FIG. 5 is a side view of FIG. 4;

FIG. 6 is a time chart showing transmission timing of an image signal input to each electrode row of the electrostatic recording apparatus of FIG. 4;

[Explanation of symbols]

 1a to 1i Signal electrode 2 Color material droplet 3 Suction electrode 4 Recording medium X Main scanning direction Z Sub scanning direction

Claims (6)

[Claims] 1. An electrostatic type in which charged color material droplets are respectively discharged from a plurality of signal electrodes and sucked to a suction electrode so that the color material droplets adhere to a recording medium located on the suction electrode. In the recording apparatus, the displacement amount of the droplet position on the recording medium of the adhesion position with respect to the discharge position of the color material droplet,
An electrostatic recording apparatus, wherein the diameter of the color material droplet on the recording medium is within 20% of the droplet diameter. 2. The electrostatic recording apparatus according to claim 1, wherein said signal electrodes are arranged in a main scanning direction and a sub-scanning direction. 3. The method according to claim 2, wherein the distance between the plurality of signal electrodes is at least a predetermined distance, so that the displacement of the color material droplet is within 20% of the droplet diameter. The electrostatic recording apparatus according to claim 1 or 2, wherein: 4. An interval between the plurality of signal electrodes is 169 μm.
4. The electrostatic image recording apparatus according to claim 3, wherein m is not less than m. 5. The method according to claim 1, wherein an image signal is supplied to the plurality of signal electrodes at different timings, so that a displacement of a droplet position of the color material droplet is within 20% of a droplet diameter. The electrostatic recording device according to claim 1. 6. The electrostatic recording apparatus according to claim 5, wherein a supply interval of the image signal is 8.45 μsec or more.