JPH11198383A - Driving method of ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a driving, by which a clear image can be formed, by a method wherein a bias voltage within a range which no discharging of an ink develops, is applied in advance of the application of at least a discharging signal voltage as the driving method of an electrostatically accelerating on- demand type ink jet recording device. SOLUTION: An image information to be formed on a recording sheet is supplied from an information supply source such as a computer to an ink jet recording device. An ink jet recording head 10 stores an ink 11 within it so as to adhere minute ink drops to the sheet in accordance with a recording information by passing the sheet through the recording device in order to form an image. Further, the head 10 has discharging slits 10a and discharging electrodes 10b at a tip formed by pinching an upper and a lower units 101 and 102 and, in addition, the sheet is provided on a counter electrode so as to form a circuit between the electrode 10b and the counter electrode in order to discharge the ink 11. In this case, a bias voltage, within the range of which no discharging of the ink deveops, is applied in advance of the application of a discharging signal voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving an ink jet recording apparatus.

[0002]

2. Description of the Related Art In an electrostatic acceleration ink jet method, as a mechanism for discharging ink in a head, for example, a voltage pulse is applied to a discharge electrode 10b shown in FIG. A general mechanism is to form an electrostatic field between them and eject ink.

The formation of a printed image is performed by an on / off signal relating to the presence or absence of a dot, and an image density information signal. The above type of ink jet recording apparatus is called an electrostatic acceleration on demand type ink jet recording apparatus. The image density information is obtained only by changing the voltage application time, that is, the pulse width.
By changing the pulse width, the ink ejection amount changes, and as a result, the printed dot area increases or decreases. However, in this method, resolution is reduced because high-density image information is dealt with only by increasing the dot diameter.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a driving method capable of forming a clear image in an electrostatic acceleration ink jet recording apparatus. It is to be.

[0005]

The above object is achieved by the following (1) to (4).
This is achieved by the present invention of (2). (1) In a method of driving an electrostatic acceleration on-demand type ink jet recording apparatus that ejects ink droplets by electrostatic force, a bias voltage in a range that does not cause ink ejection is applied at least prior to an ejection signal voltage. A method for driving an ink jet recording apparatus. (2) The method for driving an ink jet recording apparatus according to the above (1), wherein an ink having a liquid electric resistance of 10 ⁹ Ωcm or more is used.

[0006]

Embodiments of the present invention will be described below. The driving method of the electrostatic acceleration ink jet recording apparatus according to the present invention is characterized in that a bias voltage is applied in advance prior to the application of the ejection signal voltage, whereby a clear image can be formed.

Prior to the signal voltage, the bias voltage to be applied in advance may be a voltage equal to or lower than the threshold value for ink discharge, and more preferably, 10% of the threshold voltage for ink discharge.
~ 90%.

If the pre-applied voltage is less than 10% of the threshold voltage of the ink ejection, there is no effect even if the application time is prolonged. Discharge before applying the pulse voltage is likely to occur, and stable control of printing is difficult.

The ink used in the present invention is 10
It preferably has a liquid electrical resistance of ⁹ Ωcm or more. By using such an ink, the ink ejection becomes appropriate and the image quality is improved. The upper limit of the liquid electric resistance of the ink is preferably about 10 ¹⁴ Ωcm.

As the solvent for such an ink, there is preferably used a linear or branched aliphatic hydrocarbon, alicyclic hydrocarbon, or aromatic hydrocarbon, or a halogen-substituted hydrocarbon. For example, octane, isooctane, decane, isodecane, decalin, nonane, dodecane, isododecane, cyclohexane, cyclooctane,
Cyclodecane, benzene, toluene, xylene, mesitylene, isoper E, isoper G, isoper H, isoper L (Isoper: trade name of Exxon), Shelsol 70, Shersol 71 (Shelsol: trade name of Shell Oil Co.), Amsco OMS, Amsco 46
Solvent 0 (Amsco: trade name of Spirits) or the like is used alone or in combination.

Next, as the colorant used in such an ink, any pigment and dye conventionally used in an oil-based ink composition or a liquid developer for electrophotography can be used.

As the pigments, those generally used in the technical field of printing can be used irrespective of inorganic pigments and organic pigments. Specifically, for example, conventionally known pigments such as carbon black, cadmium red, molybdenum red, and chrome yellow can be used without any particular limitation.

As the dye, azo dye, metal complex dye,
Oil-soluble dyes such as naphthol dyes, anthraquinone dyes, phthalocyanine dyes and metal phthalocyanine dyes are preferred.

These pigments and dyes may be used alone or in appropriate combination, but may be contained in the range of 0.01 to 5% by weight based on the whole ink. desirable.

When a pigment is used, a dispersion polymer is used in combination to stabilize the dispersion of the pigment particles in a non-aqueous solvent. The dispersed polymer contains a repeating unit soluble in a non-aqueous solvent as a main component, and has an average molecular weight of preferably 1 × 10 ³ to 1 × 10 ⁶ , more preferably 5 × 10 ^{3 to} 5 × by weight average molecular weight Mw. The range is 10 ⁵ .

Further, in order to improve the adhesion between the printed image and the recording sheet, it is preferable that the ink contains a resin component. If the ink contains a resin component soluble in the ink solvent to such an extent that the fixability is satisfied, clogging in the head is likely to occur. Therefore, the resin component is preferably contained in the ink as dispersed particles.

As this method, a method of coating a pigment with a resin or dyeing resin particles with a dye is effective. For the method of coating the pigment with a resin, for example,
Kenji Ueki, "Flow of paint and pigment dispersion", Kyoritsu Shuppan (19
1971), "Solomon, the science of paint""Paint and Surf
ace Coating Theory Practice ", Yuji Harasaki" Coating Engineering "Asakura Shoten (1971), Yuji Harasaki" Basic Science of Coatings "Bookstore (1977), etc.

There is also a method of including resin particles separately from the coloring agent. As a method for producing resin particles having good dispersion stability in ink, for example, a conventionally known non-aqueous dispersion polymerization method may be mentioned. Chapter, CMC Publishing (1991)
), Koichi Nakamura, ed., "Development and Practical Use of Recent Electrophotographic Development Systems and Toner Materials", Chapter 3, (1985, Japan Science Information Co., Ltd., 1985), KEJ Barrett, "Dispersion P
olymerization in Organic Media "John Wiley (197
5 years).

The apparatus system shown in FIG. 1 has an ink jet recording apparatus 1 by electrostatic acceleration.

As shown in FIG. 1, first, image information to be formed on a recording sheet 2 is supplied from an information supply source such as a computer 3 to an ink jet recording apparatus 1 through a transmission means such as a path 4. The ink jet recording head of the recording apparatus 1 stores ink therein,
When the recording sheet 2 passes through the inside, fine droplets of ink are sprayed on the recording sheet 2 in accordance with the information. Thus, ink adheres to the recording sheet 2 based on the image information, and an image is formed.

FIGS. 2 and 3 show examples of the structure of an ink jet recording apparatus as in the apparatus system shown in FIG. 2 and 3, members common to FIG. 1 are denoted by common reference numerals.

FIG. 2 is a schematic structural view showing a main part of such an ink jet recording apparatus, and FIG. 3 is a partial sectional view of a head.

The head 10 provided in the ink jet recording apparatus has a slit sandwiched between the upper unit 101 and the lower unit 102, as shown in FIGS. Has become
The ejection electrode 10b is arranged in the slit, and the slit is filled with the ink 11.

In the head 10, a voltage is applied to the ejection electrode 10b according to a digital signal of image pattern information. As shown in FIG. 2, a counter electrode 10c is provided so as to face the discharge electrode 10b.
A recording sheet 2 is provided above. By applying a voltage, a circuit is formed between the discharge electrode 10b and the counter electrode 10c, and the ink 11 is discharged from the discharge slit 10a of the head 10 to form an image on the recording sheet 2 provided on the counter electrode 10c. Is done.

The width of the discharge electrode 10b is preferably as narrow as possible at the end in order to form a high-quality image, for example, to perform printing.

[0026]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples. Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Here, the following IK-1 ink was used.

Ink: IK-1 10 g of dodecyl methacrylate / acrylic acid copolymer 30 g of Isopar H and 8 g of alkali blue were charged together with glass beads into a paint shaker (manufactured by Toyo Seiki) and dispersed for 4 hours to obtain a fine dispersion of alkali blue. Was.

A blue ink was prepared by diluting 5 g of the above-mentioned alkali blue dispersion and 0.08 g of octadecene-half-maleic acid octadecylamide copolymer into 1 liter of Isopar G. The liquid electric resistance of the obtained ink was 1 × 10 ¹¹ Ω. The ink had a surface tension of 33 dyn / cm and a viscosity of 1.1 centipoise.

Using the above-described ink and the recording apparatus shown in FIG. 1, printing was performed by applying bias voltages having various pulse widths prior to the rectangular ejection signal voltage as shown in FIG. Using a pulse of +2 KV and 150 μsec as a signal voltage, a threshold voltage (+1.5 K
V) was fixed at +1 KV, which is 67% of V). Oji Keiseki Co., Ltd. uses dots of commercially available high-quality paper as the recording paper.
It examined using the micro densimeter DA5000 made by company. Here, the recording frequency was fixed at 3 kHz. Table 1 shows the results. As can be seen from the table, by applying the bias voltage prior to the signal voltage, a print with high image density and good image quality with little blurring was obtained without using special paper for ink jet. No change in dot diameter due to a change in bias pulse width was observed. Then, next, the pulse width of the bias voltage was fixed to 100 μsec, the pulse width of the signal voltage was changed, and the gradation reproducibility was examined. Other conditions are the same as above. As can be seen from Table 2, the dot diameter increases in proportion to the increase in the pulse width of the signal voltage, so that the gradation becomes excellent, the image density is high even for small dots, and good image quality with less blur is obtained. Prints were obtained.

[0030]

[Table 1]

[0031]

[Table 2]

Example 2 Printing was performed under exactly the same conditions as in Example 1 except that the bias was always applied. As a result, as in Example 1, a printed matter having excellent gradation, high density, and good image quality with little blurring was obtained.

Comparative Example Printing was performed under the same conditions as in Example 1 except that no bias was applied. Other conditions are the same. The results are shown in Table 3. The dot density was reduced, the dot diameter was increased due to the occurrence of bleeding, the shape was deteriorated, and the image quality was significantly deteriorated.

[0034]

[Table 3]

[0035]

According to the present invention, a clear image can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an apparatus system used in the present invention.

FIG. 2 is a schematic configuration diagram illustrating a main part of an inkjet recording apparatus used in the present invention.

FIG. 3 is a partial sectional view of a head of an ink jet recording apparatus used in the present invention.

FIG. 4 is a graph showing an example of a signal voltage applied according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink jet recording apparatus 2 Recording sheet 3 Computer 4 Pass 10 Head 10a Discharge slit 10b Discharge electrode 10c Counter electrode 11 Ink 101 Upper unit 102 Lower unit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Eiichi Kato 4000 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture Inside Fujisha Shin Film Co., Ltd.

Claims (2)

[Claims] 1. A method for driving an electrostatic acceleration on-demand type ink jet recording apparatus which ejects ink droplets by electrostatic force, wherein a bias voltage in a range where ink ejection does not occur is applied at least prior to an ejection signal voltage. Driving method for an ink jet recording apparatus. 2. The method according to claim 1, wherein an ink having a liquid electric resistance of 10 ⁹ Ωcm or more is used.