JPH08174806A - INKJET PRINT HEAD AND INKJET PRINTER USING THE SAME - Google Patents

Abstract

(57) [Summary] [Purpose] Prevents satellite droplets from landing on the printed material.
Provided is an inkjet printhead that can perform good printing and printing. [Structure] An ink containing portion 3 that contains ink 1 therein and has an ink ejection hole 6 that ejects the ink 1, and an electrostrictive element 4 that ejects the ink 1 from the ink ejection hole 6.
And an electrode 7 provided on the peripheral edge of the opening of the ink ejection hole 6. Then, by energizing the electrodes 7, the ink 1 in the ink chamber 2 is charged immediately before the ink 1 is ejected, and then the ink 1 in the ink chamber 2 is charged to a polarity opposite to that of the charge immediately after the ink is ejected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet print head and an ink jet printer of an ink jet system for ejecting liquid ink into fine particles from a nozzle for recording.

[0002]

2. Description of the Related Art There are various recording systems for color printers, such as an inkjet system, a fusion type thermal transfer system, a sublimation type thermal transfer system and an electrostatic system.

Among them, the ink jet system is characterized in that it has a high resolution, has no gloss, can express an astringent color, and has a relatively low running cost and can record on a large size paper.

For this reason, it is often used for large posters, apparel, and interior monitors. In particular, since a matte color is suitable for expressing the texture of cloth, there is a high demand for apparel.

By the way, a head used in an ink jet printer adopting an ink jet system is an ink containing section for containing ink, and an ink ejecting member including a piezoelectric element for ejecting ink from an ink ejecting hole formed in the ink containing section. Means and means.

In this ink jet print head,
By applying an ejection pulse to the piezoelectric element, the ink in the ink containing portion is made into fine particles and sprayed onto the print paper through the ink ejection holes, so that printing or printing is performed on the print paper.

[0007]

However, in the ink jet print head, due to the generation of satellite droplets,
There is an inconvenience that the quality of printing and printing deteriorates. That is, since the satellite droplets land around the main dot droplets when the ink droplets land on the print paper or the like, the quality of printing or printing deteriorates.

Therefore, the present invention has been proposed to solve the problems of the prior art, and an ink jet print head capable of preventing satellite droplets from landing on a material to be printed and performing good printing and printing. And an inkjet printer.

[0009]

An ink jet print head according to the present invention accommodates ink therein and has an ink accommodating portion having an ink ejection hole for ejecting the ink,
An ink ejecting unit for ejecting ink from the ink ejecting hole and an electrode provided on the peripheral edge of the opening of the ink ejecting hole are provided. Then, in order to prevent the satellite droplets from landing on the printed material, the ink in the ink containing section is charged immediately before the ink is discharged by energizing the electrodes, and then the ink in the ink containing section is charged immediately after the ink is discharged. And the opposite polarity.

On the other hand, the ink jet printer according to the present invention has a rotary drum around which a material to be printed is wound around the peripheral surface of the drum, and an ink jet print head according to the present invention which prints on the material to be printed. And head moving means for moving the inkjet print head parallel to the axis of the rotary drum.

Then, the inkjet print head is fixed or moved while rotating the rotary drum to print in the rotating direction of the rotary drum, or the inkjet print head is moved with the rotary drum fixed to move the object to be printed. After printing in the width direction (so-called line direction), the printing material is sent to the next printing position by the rotary drum, and similarly, the inkjet print head sequentially prints the printing material in the width direction.

The ink jet print head may be one, or a plurality of ink jet print heads may be arranged in a line along the axial direction of the rotary drum.

[0013]

In the ink jet print head according to the present invention, an electrode is provided on the periphery of the opening of the ink discharge hole, and the ink in the ink containing section is charged immediately before the ink is discharged by energizing the electrode. Immediately after ejection, the ink in the ink containing portion is charged to the opposite polarity to the above-mentioned charge, so a Coulomb force is generated between the satellite droplets ejected from the ink ejection holes and the ink in the ink containing portion, and the satellite droplets form an ink meniscus. Is absorbed by.

On the other hand, in the ink jet printer according to the present invention, since the ink jet print head is used, satellite droplets are prevented from landing on the printing object, and good printing and printing can be performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described in detail below with reference to the drawings.

First, the structure of the ink jet print head will be described. As shown in FIG. 1, the ink jet print head of this embodiment includes an ink containing portion 3 having an ink chamber 2 containing the liquid ink 1, and an ink ejecting means for ejecting the ink 1 from the ink containing portion 3. It is composed of a certain electrostrictive element 4.

The ink containing portion 3 has an ink chamber 2 having a space sufficient to contain the ink 1. The ink containing portion 3 is provided with an ink supply path 5 on one end side and an ink ejection hole 6 for ejecting the ink 1 on the other end side opposite to the ink supply path 5. The ink 1 is supplied from the ink supply path 5 into the ink chamber 2, and the electrostrictive element 4 is supplied.
Is ejected from the ink ejection hole 6.

The electrostrictive element 4 is for ejecting the ink 1 in the ink chamber 2 from the ink ejection hole 6 based on the printing and printing data, and dents a part of the outer wall portion of the ink containing portion 3. It is provided in the open part. For example, an ejection pulse based on printing and printing data is applied to the electrostrictive element 4. As the ink ejecting means, conventionally known on-demand ejection technology can be adopted in addition to the electrostrictive element 4.

In particular, in this ink jet print head, an electrode 7 is provided at the peripheral edge of the ink discharge hole 6 in order to prevent satellite droplets from landing on the printing object and to perform good printing and printing. . Voltages in different directions are applied to the electrode 7 immediately before and immediately after the ink 1 is ejected.

The ink jet print head constructed as described above operates as follows. First, FIG.
As shown in (a), the ink 1 supplied into the ink chamber 2 via the ink supply path 5 is guided to the ink ejection hole 6. Then, an ink meniscus 8 is formed in the ink ejection hole 6 by the surface tension of the ink 1, and a standby state is set.

At this time, as shown in FIG. 2B, a discharge pulse (for example, +20 V, pulse width 100) is applied to the electrostrictive element 4.
μsec) and the electrode 7
Ink charging pulse (eg + 100V, pulse width 10
0 μsec) is applied to charge the ink 1.

Next, when the ejection pulse reaches t ₂ , as shown in FIG.
Ink columns 9 are formed as shown in FIG. After that, for example, after 50 μsec, the ink column 9 is formed in FIG.
As shown in FIG. 3, the ink droplets are divided into main dot droplets 10 and satellite droplets 11.

At this time, as shown in FIG. 4B, an ink charging pulse having a polarity opposite to that of the ink charging pulse previously applied to the electrode 7 (eg, -100V, pulse width 100 μs).
ec) is applied to charge the ink 1 in the ink chamber 2 to the opposite polarity to the main dot droplet 10.

Then, a Coulomb force is generated between the satellite droplet 11 and the ink 1, and the satellite droplet 11 is absorbed by the ink meniscus 8 as shown in FIG. 5 (a). As a result, only the main dot droplet 10 is ejected from the ink ejection hole 6.

Next, an ink jet printer using this ink jet print head will be described. First, a so-called drum rotation type printer will be described.

As shown in FIG. 6, the rotary drum type printer includes a rotary drum 12 and a print paper 13 which is a material to be printed wound around the peripheral surface of the rotary drum 12.
An inkjet print head 14 that prints on the print paper 13 and the inkjet print head 1
4 is composed of a lead screw 15 which is a head moving means for moving the rotary drum 4 in parallel with the axis of the rotary drum 12.

The rotary drum 12 is formed of a cylindrical drum, and is rotated in a direction indicated by an arrow A in the drawing by, for example, a drive belt 18 wound around a motor 16 and a rotary shaft 17 of the rotary drum 12. It is done like this. A print paper 13 is wound around the peripheral surface of the rotary drum 12 so that the print surface is the front side. The print paper 13 is fixed to the rotary drum 12 at both the winding start portion and the winding end portion.
2 fixed in place.

On the other hand, the ink jet print head 14
Is moved in the width direction of the print paper 13 in the direction indicated by the arrow B in the drawing by the lead screw 15 arranged in parallel with the rotary shaft 17 of the rotary drum 12. That is, the inkjet print head 14 is fixed to the head mounting portion 19 mounted on the lead screw 15 arranged parallel to the rotation shaft 17 of the rotary drum 12, and keeps the distance between the head 14 and the print paper 13 constant. Meanwhile, the print paper 13 is moved in the width direction.

As the head moving means, in addition to the lead screw 15, a head and a motor may be used.

In order to print on the print paper 13 by the ink jet printer having the above construction, the rotary drum 12 is rotated, and ink is ejected from the ink jet print head 14 in synchronization with the printing, so that the printing is performed.
Then, when printing of that portion is completed (usually, the drum makes one revolution), the inkjet print head 14 is moved to the next print position.

The ink jet print head 14 is moved stepwise to the next print position each time printing is completed, or is gradually moved while printing.
In the case of a multi-nozzle head or a configuration in which the same place is printed several times, step feed is suitable.
Print while sending in conjunction with 2. Rotating drum 12
When printing is carried out while moving the inkjet print head 14 in conjunction with the rotation of, the printing becomes spiral.

Next, a serial type printer will be described. In such a serial type printer, as shown in FIG. 7, the basic configuration is almost the same as that of the drum rotating type printer, but the print paper 13 is not fixed to the rotating drum 12 but is attached to the peripheral surface of the rotating drum 12. The wound print paper 13 is configured to be fed by the pressure roller 20. A platen may be used for the rotary drum 12.

In order to print with this serial type printer, first, one line is printed on the print paper 13 while moving the ink jet print head 14 in the width direction of the print paper 13 by the lead screw 15. Thereafter, the rotary drum 12 and the pressure roller 20 feed the print paper 13 to the next printing position, and similarly, the inkjet print head 14 is moved to perform printing on the print paper 13.

The printing is performed only when the ink jet print head 14 is fed in the same direction.
Printing may be performed at any time of feeding and returning.

Next, a line type printer will be described. In such a line type printer, as shown in FIG. 8, a line head 21 in which a plurality of inkjet print heads are arranged in a line along the axial direction of the rotary drum 12 is provided. Type printer is almost the same configuration.

In printing with this line type printer, a line is printed on the print paper 13 by ejecting ink from a plurality of ink jet print heads at the same time. Then, after printing is completed, the rotary drum 12 (or platen) feeds the print paper 13 for one line, and the line head 21 simultaneously prints the next line.

In this example, printing is performed line by line, but it is also possible to print all lines at once, divide into a plurality of blocks for printing, or alternately print every other line. .

Next, the control mechanism of the above-mentioned ink jet printer will be described with reference to the block diagram of the signal processing and control system shown in FIG. The print data is arranged in the print order by the signal processing / control circuit unit 22 and transmitted to the head 24 through the driver 23. The printing order differs depending on the configurations of the head 24 and the printing unit. Also, the print order is
There is also a relation with the input order of the print data, and if necessary, the data is once recorded in the line buffer memory 25 or the single screen memory and then taken out.

The head 24 has gradation signals (nozzles),
The ejection signal (each nozzle or all at once) is output. Incidentally, in the conventional inkjet, only the ejection signal is usually output.
When the number of nozzles is very large in a multi-head, an IC is mounted on the head section to reduce the number of wirings connected to the head 24. This is the same as in the case of a normal thermal head.

The correction 26 includes γ correction, color correction in the case of color, and variation correction of each head 24. As for the correction 26, predetermined correction data is stored in a ROM map format, and external conditions such as nozzle number (nozzle N
o. ), Temperature, input signal, etc.

Various controls 27 include driving a motor,
It includes system control such as synchronization, cleaning of the head 24, and other paper supply and discharge. The signal processing / control circuit unit 22 is generally processed by software as a central processing unit (CPU) or digital signal processing unit (DSP) configuration. Of course, the signal input includes an operation unit signal and an external control signal in addition to the print data.

[0042]

As is apparent from the above description, according to the ink jet print head of the present invention, an electrode is provided at the peripheral edge portion of the opening of the ink ejection hole, and immediately before the ink is ejected by energizing this electrode. After the ink in the ink containing portion is charged, immediately after that, the ink in the ink containing portion is charged with a polarity opposite to the above charge, so that the satellite droplets can be captured and absorbed in the head.

Therefore, in the ink jet printer using this ink jet print head, satellite droplets are prevented from landing on the object to be printed, good printing and printing can be performed, and high quality printing can be realized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an inkjet printhead to which the present invention has been applied.

2A and 2B are diagrams for explaining the operation of an inkjet print head to which the present invention is applied. FIG. 2A is a sectional view showing a state where an ink meniscus is formed, and FIG. 2B is a pulse waveform applied to an electrostrictive element and an electrode, respectively. FIG.

3A and 3B are diagrams for explaining the operation of an inkjet print head to which the present invention is applied. FIG. 3A is a cross-sectional view of a state in which an ink column is formed, and FIG. 3B is a pulse waveform applied to an electrostrictive element and an electrode, respectively. FIG.

4A and 4B are diagrams for explaining the operation of an inkjet print head to which the present invention is applied. FIG. 4A is a cross-sectional view of a state in which satellite droplets and main dot droplets are formed, and FIG. It is a figure which shows the pulse waveform which applies a pulse of polarity.

5A and 5B are diagrams for explaining the operation of an inkjet print head to which the present invention is applied, where FIG. 5A is a cross-sectional view of a state where satellite droplets are absorbed by an ink meniscus, and FIG. It is a figure which shows the pulse waveform which applied the pulse of polarity.

FIG. 6 is a perspective view of a drum rotation type inkjet printer.

FIG. 7 is a perspective view of a serial type inkjet printer.

FIG. 8 is a perspective view of a line type inkjet printer.

FIG. 9 is a block diagram of a signal processing and control system.

[Explanation of symbols]

 1 Ink 2 Ink Chamber 3 Ink Storage Section 4 Electrostrictive Element 6 Ink Discharge Hole 7 Electrode 8 Ink Meniscus 9 Ink Column 10 Main Dot Drop 11 Satellite Drop 12 Rotating Drum 13 Print Paper 14 Inkjet Printhead 15 Lead Screw 17 Rotation Axis 20 Pressure Bonding Laura 21 line head

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Claims (4)

[Claims] 1. An ink containing portion for containing ink therein and having an ink ejecting hole for ejecting the ink, an ink ejecting means for ejecting ink from the ink ejecting hole, and a peripheral portion of an opening of the ink ejecting hole. The ink in the ink containing section is charged immediately before the ink is discharged by energizing the electrode by charging the electrode, and then the ink in the ink containing section is charged to the opposite polarity to the charge immediately after the ink is discharged. An inkjet print head characterized in that 2. A rotary drum which winds a material to be printed on the peripheral surface of the drum so that the printing surface is the front surface, an inkjet printhead according to claim 1 which performs printing on the material to be printed, and the inkjet printhead is rotated. An ink jet printer, comprising: a head moving unit that moves in parallel with the axis of the drum, wherein the inkjet print head is fixed or moved while rotating the rotary drum to print in the rotational direction of the rotary drum. Printer. 3. A rotary drum for winding an object to be printed on the peripheral surface of the drum so that the printed surface is the front surface, an inkjet printhead according to claim 1 for performing printing on the object, and the inkjet printhead is rotated. A head moving unit that moves in parallel with the axis of the drum is provided, and after the inkjet print head is moved while the rotating drum is fixed and printing is performed in the width direction of the substrate to be printed,
An ink jet printer characterized in that the material to be printed is sent to the next printing position by a rotary drum, and similarly, it is sequentially printed in the width direction of the material to be printed by an ink jet print head. 4. The ink jet printer according to claim 2, wherein a plurality of ink jet print heads are arranged in a line along the axial direction of the rotary drum.