JPH05220967A - Ink jet head - Google Patents

Abstract

PURPOSE:To ensure the sealing of a nozzle and prevent the clogging of the nozzle by automatically closing a cap as well as covering the nozzle with a non-poar liquid even when a power source of the printer is turned off in the printing. CONSTITUTION:A cap 10 is placed at a position where it can cover the front face of a nozzle substrate 1 and can slide in the direction of the arrow P by the action of a spring 9. A drive means that acts on an arm 10b of the cap 10 against the force of the spring is, for example, an electric magnet which is integrally constituted with or built in an ink jet head 30. When a power source is turned off during the printing or the printer is in a standby condition without generating a print signal, an application of a voltage that activates the drive means is stopped so that the cap automatically moves to a position wherein the cap 10 closes the nozzle 5 by the pressing force of the spring 9. In addition, non-poar liquid seals the nozzle 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head for ejecting ink droplets onto a recording medium in an ink jet printer to form characters and figures by dots.

[0002]

2. Description of the Related Art Ink jet printers, which eject ink droplets from a plurality of nozzles in accordance with input information to form characters and figures by dots, can record and write with high print quality on plain paper with low noise and low running cost. It is superior to other types in terms of points. However, on the other hand, in this type of printer, clogging occurs due to solidification of ink in the nozzle portion or deposition of the nozzle material by the ink component. In that case, normal ejection of ink from one or a plurality of nozzles is hindered, which causes a problem that dots are not formed at a certain position on a matrix for forming characters / figures.

Conventionally, to solve such a problem, there are a cap that is pressure-bonded to the nozzle surface of the head to prevent evaporation of water from the nozzle and a device that replenishes water in the cap.

For example, as disclosed in Japanese Utility Model Laid-Open No. 62-178150, Japanese Utility Model Laid-Open No. 63-47136, or Japanese Patent Laid-Open No. 3-138156, rubber for covering and protecting the ink jet nozzle portion, etc. There is a cap which is made of an elastic member to prevent printing defects due to clogging due to ink drying in the nozzle portion and flight deflection of ink droplets. However, in such a configuration, the nozzle portion is exposed to the air in the cap, so the effect of preventing clogging is not perfect. In addition, Japanese Examined Fair 3-43
In the case of Japanese Patent Laid-Open No. 066, an ink absorber impregnated with ink is provided in a portion that comes into pressure contact with the nozzle portion so that the nozzle portion is completely sealed. There is a problem that the attached paper dust, paper fluff, dust, etc. are attached to the nozzle portion. Further, in the case of any of the above-mentioned conventional examples, there is no means for automatically capping, so that the printer is turned off during printing and the head is left uncapped and left for a long time. Will be clogged.

Further, as a conventional example, Japanese Patent Laid-Open No. 3-132
As disclosed in Japanese Patent Publication No. 356,356, there is an inkjet recording apparatus using a hot melt ink, in which the nozzle opening is brought into contact with a sealing liquid to be sealed, but the ink is limited to the hot melt. And
Further, there is a problem that the structure is complicated.

In the case of Japanese Patent Publication No. 3-51586,
Although the seal plate is directly arranged on the recording mechanism, in this case also, the head is not automatically capped when the power of the printer is turned off during printing.

[0007]

As described above, according to the conventional invention, when the power of the printer is turned off during printing, the head is left uncapped and the head is left unattended for a long time. It has a problem that clogging occurs. Some caps can be operated by a battery, a capacitor, or a relay even when the power is turned off, but there is a problem in that a device for that amount is required and the cost becomes high.

In particular, in the case of an ink using a pigment as a coloring material, the printing quality is good, but on the other hand, clogging is likely to occur, so that the conventional ink jet head is not suitable for practical use and cannot take advantage of it.

Further, the structure of the cap according to the conventional invention has a problem that the nozzle portion is not completely sealed.

The present invention has been made in view of the above problems, and an object of the present invention is to print characters and figures even when the printer is turned off during printing and left as it is for a long time. It is an object of the present invention to provide an inkjet head in which the dots forming the dots are always formed normally and the recording on the print medium can be clearly and easily discriminated. In particular, it is to provide a new ink jet head that makes it possible to practically use an ink using a pigment as a coloring material and has a clear printing quality and high reliability.

[0011]

The present invention has been made to solve the above problems, and in an ink jet head having a nozzle for ejecting ink, it is always energized in a direction to close the front surface of the nozzle. A cap, an actuation means that is energized when the ink jet head is actuated, and opens the cap against the biasing force thereof, and a non-polar solvent injected into the gap between the nozzle and the cap. It is characterized by.

[0012]

[Function] Since the cap is always urged in the direction of closing the front surface of the nozzle, the printer is turned off during printing,
Even if it is left as it is for a long period of time, when the power is turned off, the energization to the operating means is stopped and the cap is automatically closed. Then, the non-polar solvent that is incompatible with the ink is injected into the gap between the nozzle and the cap, so that the nozzle portion is completely sealed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

First, an example of a recording mechanism section of an ink jet head to which the present invention is applied will be described. 1 is a perspective view showing the whole thereof, and FIG. 3 is a sectional view showing a recording mechanism portion. The basic structure is nozzle substrate 1, pressure chamber 2,
The elastic plate 3 and the laminated piezoelectric element 4 constitute a pressure generating portion. The material of the nozzle substrate 1 is a nickel electroformed plate, but a molding resin, a stainless plate, or a glass plate may be used.
The material of the pressure chamber 2 is a molding resin such as polysulfone or polycarbonate, or a material obtained by etching glass, but it may be composed of a photosensitive resin, a photosensitive glass, or a stainless plate. The elastic plate 3 is made of a material such as polyimide, polyester, or polycarbonate which has a deformable thickness and is durable in strength, and sputters or vapor-deposits a metal such as aluminum, gold, or copper for the purpose of preventing the moisture of the ink from permeating to the outside. , Laminated or the like. The pressure generating section uses the vibration of the laminated piezoelectric element 4 in the vertical direction, and is connected to a drive circuit (not shown). The nozzle arrangement is 12 × 4 rows, but as shown in FIG. 2, any combination of the number of nozzles and the number of rows, such as 48 × 1 row or 64 × 1 row, and diagonal 1 row, may be used. Further, the method of the inkjet head is not limited to any method such as one utilizing lateral vibration of the piezoelectric element in the pressure generating portion and one in which the ink is heated and vaporized by the heating means to be ejected.

The above is the description of the recording mechanism portion of the ink jet head of the present invention.

Next, an embodiment of the ink jet head according to the present invention will be described. In FIG. 1, the cap 10 is formed of a thin plate-like member, is attached so as to cover the front surface of the nozzle substrate 1, and is a spring for constantly urging the front surface of the nozzle 5 in the direction of closing (the direction of arrow P). It is provided with an abutting portion 10c with which 9 abuts, an arm portion 10b with which an actuating means that opens against the biasing force thereof abuts, and an opening portion 10d that does not obstruct when ink is ejected from the nozzle 5. Further, the bent portion 10a of the cap 10 engages with the groove portion 7 formed by the head body 20 and the nozzle substrate 1 from the vertical direction as shown in FIG. 3, and is slidable in the directions of arrows P and F. There is. When the head is not in operation,
As shown in (B), the opening 10d has the nozzle 5 of the head.
The stopper 8 is biased by the spring 9 in a position displaced from the nozzle 5, that is, in the direction of closing the nozzle 5 (direction of arrow P).
The state where the bent portion 10a is in contact with is maintained. The actuating means acting on the arm portion 10b against the biasing force of the spring 9 is, for example, the spring 9
Is an electromagnetic magnet having a force large enough to overcome the force generated by the inkjet head 30 and is integrally assembled with the ink jet head 30 or incorporated therein, but the operating means is not limited to this.

Next, the non-polar solvent 7 will be described with reference to FIGS. 3 and 4 which is a cross section taken along the line AA of FIG. The non-polar solvent 7 is composed of one or more of a silicon-based solvent, a hydrocarbon-based solvent, and a fluorine-based solvent, and flows from the non-polar solvent reservoir 11 through the slit 21 by the capillary force to the groove portion 7.
And it penetrates into the gap between the nozzle substrate 1 and the cap 10. In the capped state (FIG. 1B), the nozzle 5 is covered. Since the non-polar solvent 7 is incompatible with the ink made of a polar solvent, it does not adversely affect printing. In addition, even if they are compatible with each other, unnecessary ink and the non-polar solvent 7 can be removed by ejecting a dummy ink immediately before the start of printing.

In this structure, the ink guided from the ink cartridge (not shown) reaches the pressure chamber 2 by the capillary force. When a printing operation is performed, a voltage of 15 to 30 V is applied to the laminated piezoelectric element 4 according to an input signal, and the laminated piezoelectric element 4 expands and displaces in the direction of arrow D to bend the elastic plate 3. The pressure chamber 2 is pressurized. The ink in the pressure chamber 2 instantaneously moves in the direction of the nozzle 5 and the supply side (not shown) accordingly, but ink droplets are ejected from the nozzle 5 toward the outside. Multilayer piezoelectric element 4
When the ink is contracted and displaced in the direction opposite to the arrow D, the ink flows into the pressure chamber 2. With the above operation, stable printing can be continued during normal operation.

However, when the power of the printer is turned off during printing and the nozzle front face of the head is left uncapped for a long period of time, ink in the nozzle portion is solidified and clogging occurs. Further, in the case of an ink using a pigment as a coloring material, it is particularly easy to solidify. The inkjet head of the present embodiment can deal with these problems. That is, when the power is turned off during printing, the voltage applied to the actuating means (for example, an electromagnetic magnet) acting on the arm 10b against the biasing force of the spring 9 is also not applied, so that the spring is automatically operated. The cap 10 moves in the direction of arrow P by the urging force of 9, and the nozzle 5 is covered as shown in FIG. Therefore, evaporation of ink from the nozzles 5 is prevented and clogging is prevented. Further, in this state, the non-polar solvent 7 which is made of a polar solvent and is incompatible with the ink covers the opening of the nozzle 5 to completely shut off the outside air and maintain a state in which the hermeticity is improved. . When the printing operation is performed, since the power is turned on, the actuating means working on the arm 10b is also energized. As a result, the cap 5 moves in the direction of arrow F in FIG.
Since 0d comes to the position of the nozzle 5, there is no obstacle even if ink is ejected from the nozzle 5. Further, in a standby state where the printer is powered on and a print signal is not generated, it is possible to cancel the application of the voltage to the operating means that acts on the arm portion 10b.

[0020]

According to the present invention, since the cap is always urged in the direction of closing the front surface of the nozzle, the printer is turned off during printing and left in the same state for a long time. However, when the power is turned off, the power is not supplied to the operating means, and the cap is automatically closed. This prevents evaporation of ink from the nozzles,
The problem that dots cannot be formed when printing is performed at the next opportunity can be prevented. Further, in the present invention, since a non-polar solvent that is incompatible with the ink is injected into the gap between the nozzle and the cap to cover the nozzle portion, the ink from the nozzle is completely sealed even when left for a long time. It prevents the evaporation of and has a great effect on clogging.

That is, the dots forming characters / figures are always formed normally, and the recording on the print medium can be clearly and easily discriminated, so that the reliability of the ink jet head can be greatly improved. In particular, in the case of an ink using a pigment as a coloring material, although it was superior in printing quality to an ink using a dye, it could not be practically used because it was easily clogged. According to the present invention, it is possible to provide a new inkjet printer with good printing quality and high reliability. Further, the device is simpler and the cost can be reduced as compared with the device in which the capping operation is performed by the battery, the capacitor or the relay after the power is turned off.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an inkjet head of the present invention, (a) is a perspective view showing a state during printing, and (b) is a perspective view showing a state during non-printing.

FIG. 2 is a perspective view of an inkjet head showing a second embodiment.

FIG. 3 is a cross-sectional view of an inkjet head.

4 is a cross-sectional view taken along the line AA of FIG.

[Explanation of symbols]

 1 Nozzle Substrate 2 Pressure Chamber 3 Elastic Plate 4 Laminated Piezoelectric Element 5 Nozzle 9 Spring 10 Cap 11 Nonpolar Liquid 30 Inkjet Head

Claims (3)

[Claims] 1. In an inkjet head having a nozzle for ejecting ink, a cap that is constantly energized in a direction to close the front surface of the nozzle, and a cap that is energized when the inkjet head is activated to apply the energizing force to the cap. An ink jet head comprising: an actuating means that opens against resistance; and a non-polar solvent that is injected into a gap between the nozzle and the cap. 2. The ink jet head according to claim 1, wherein the non-polar solvent is one or more of a silicon-based solvent, a hydrocarbon-based solvent, and a fluorine-based solvent. 3. The ink according to claim 1 or 2, wherein the ink is a water-based pigment ink composed of a polar solvent.
The described inkjet head.