JP3758184B2 - Inkjet recording head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a maintenance technique in an ink jet recording apparatus that records on recording paper by ejecting ink droplets from nozzles.
[0002]
[Prior art]
FIG. 1 is a configuration diagram illustrating an example of the periphery of a head of an inkjet recording apparatus. In a state where printing is not performed at the end of the printing operation or during standby, the head 1 is capped by the capping means 2 in order to prevent clogging due to ink evaporation from the nozzles. The cap blocks the head from the outside air, and the moisturizing effect due to the evaporation of ink absorbed by the ink absorber 3 such as a sponge provided inside the cap suppresses the increase in the viscosity of the ink in the nozzle portion, and also causes the clogging to progress. It is suppressed.
[0003]
However, during printing, the cap is removed from the head and opened. For this reason, as a recovery operation that ejects a predetermined number of ink droplets from all nozzle openings of each recording head at regular intervals, in order to prevent drying and sticking of nozzles that are infrequently used and infrequently used In other words, a refresh operation is performed. This refresh operation is effective in preventing clogging and recovering from clogging, but consumes extra ink other than the recorded image.
[0004]
FIG. 2 shows an example of a sectional view of an ink jet recording head in the prior art. 10 is an orifice plate, 20 is an ink chamber, 30 is a fixing member, 40 is an ink supply tube, and 50 is an ink cartridge. The ink 60 is supplied from the ink cartridge 50 to the common ink chamber 21 through the supply tube 40 and the fixing member 30. The ink 60 held in the common ink chamber 21 passes through the ink supply port 22, the pressure generation chamber 23, and the communication port 24 communicating with the ink discharge port, and the nozzle opening provided in the orifice plate 10. 11, ink droplets are ejected.
[0005]
In order to obtain a good image in an ink jet printer, it is important that an appropriate meniscus is obtained with a nozzle. Normally, when printing is not performed for a long time, the head is capped to prevent an increase in meniscus viscosity due to evaporation of moisture and other volatile components in the ink. However, the head at the time of printing does not always eject ink, and printing and non-printing are repeated. In particular, in the case of the heads arranged on the line in the width of the printing paper, there is a region with a relatively low printing load. For this reason, in the non-driven nozzle, evaporation of moisture and volatile matter in the ink proceeds from the ink discharge port, and the viscosity of the meniscus increases. Furthermore, as the drying progresses, the ink component forms a film on the meniscus surface, leading to ejection failure and nozzle clogging when resuming printing.
[0006]
Therefore, in order to obtain good printing, the meniscus vibrates enough to prevent ink from being ejected when not driven, in order to prevent the ink component from forming a film on the meniscus surface or to destroy the formed film. So-called refreshing is performed in which a normal meniscus is obtained by oscillating the ink to be added and periodically ejecting ink on the meniscus surface having increased viscosity from the nozzles.
[0007]
However, frequent refreshing for head maintenance results in a decrease in printing speed. Further, ink ejected by refresh for head maintenance is not used for printing. In order to reduce the consumption of ink used for purposes other than printing, the number of refreshes may be reduced. However, if the number of refreshes is insufficient, ejection failure or nozzle clogging may occur.
[0008]
In addition, in the serial method in which printing is performed with a relatively slow speed and the head moves, frequent refresh operations are possible. However, in the line method characterized by high-speed printing, refreshing that causes a decrease in printing speed is frequently performed. This causes a decrease in printing performance.
[0009]
With respect to rocking, which is the other maintenance operation, ink is not consumed since it does not reach ink ejection. However, frequent swinging takes a lot of time other than printing, which also causes a decrease in printing speed.
[0010]
[Problems to be solved by the invention]
An object of the present invention is to solve these inconveniences and to obtain an ink jet recording apparatus which does not cause a discharge failure without causing a decrease in printing speed and excessive ink consumption for maintenance.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a common ink chamber that stores ink, an ink supply port that communicates with the common ink chamber, a pressure generation chamber that communicates with the ink supply port, and a target by ejecting ink. A recording head comprising a plurality of nozzle openings for recording on a recording material, wherein the orifice plate is made of a porous member that can be impregnated with ink, and the orifice outlet side of the orifice plate The surface of the film is subjected to ink repellent treatment.
[0012]
Further, the orifice plate seals one surface of a common ink chamber that supplies ink to each nozzle opening for discharging ink.
[0013]
A common ink chamber that stores ink; an ink supply port that communicates with the common ink chamber; a pressure generation chamber that communicates with the ink supply port; and a plurality of nozzles that eject ink and record on a recording material A recording head comprising an orifice plate having an opening, wherein the orifice plate is made of a porous member that can be impregnated with ink, and the surface of the orifice plate has been subjected to a surface treatment without ink permeability. Features.
[0014]
In addition, an ink supply path to the common ink chamber and a second supply path for supplying moisturizing liquid or ink to the orifice plate are provided.
[0015]
The second communication port is connected to an orifice plate at one end and a suction pump to the other end.
[0016]
Further, the surface of the orifice plate on the ink chamber side is treated with an ink affinity, and the surface of the ink ejection side is treated with an ink repellent.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
[0018]
FIG. 3 is a cross-sectional view showing the configuration of the first example of the ink jet recording head in the present invention. FIG. 4 is an enlarged view of the nozzle portion of the head of the first example of the present invention.
[0019]
Here, the difference from the prior art is that the orifice plate 10 constituting the nozzle opening 11 is formed of a porous member capable of impregnating and holding a liquid, for example, a metal made by sintering or a ceramic material. There is to be.
[0020]
When a porous material is used for the orifice plate 10 and its properties are utilized, when ink is filled in the head, the orifice plate 10 has a surface in contact with the common ink chamber and around the nozzle opening. In addition, the ink is permeated and held by capillary action.
[0021]
That is, the area around the meniscus 17 shown in FIG. 4 is always moisturized, and ink drying can be suppressed as much as possible even when the cap is opened. Further, the surface of the orifice plate 10 on the discharge opening side is subjected to a surface treatment of the ink repellent film 18 so as to prevent the ink from exuding to the surface of the orifice plate 10 other than around the nozzle.
[0022]
Furthermore, only the periphery of the nozzle opening has a slightly recessed shape, and the ink repellent treatment is not applied to that portion, so that the meniscus moisture retention can be more effectively maintained.
[0023]
FIG. 5 shows a second example of the present invention. A second communication port 41 provided in the fixing member 30 is directly connected to the orifice plate 10. A moisturizing liquid (for example, glycerin having a reduced viscosity) that does not cause a problem even when mixed with ink is supplied to the second communication port 41 so as to permeate and hold in the orifice plate 10.
[0024]
Further, the surface of the orifice plate 10 (including the surface on the ink chamber side opposite to the surface on the ejection opening side) is subjected to a surface treatment that does not transmit ink so that it does not mix with ink in the common ink chamber. It has become.
[0025]
Here, the surface treatment that does not transmit ink is specifically the formation of a film on the surface of the multi-material member by metal, resin, or a composite thereof, and in particular, a surface treatment that has a function as a water-repellent film. Indicates. Examples of the treatment method include a plating treatment, a treatment by a vacuum deposition method or a sputtering method, or a coating treatment generally used for a magnetic tape or the like.
[0026]
Further, it is preferable that the surface of the orifice plate 10 on the ink chamber side is subjected to ink affinity treatment, and the surface treatment on the ejection opening side is subjected to ink repellent treatment. The reason for this is that the surface of the orifice plate 10 on the ink chamber side is subjected to ink-philic treatment, so that ink priming is facilitated, and the surface treatment on the ejection opening side is subjected to ink repellent treatment. This is because there is an improvement in straightness and cleaning performance.
[0027]
Due to the effect of the moisturizing liquid impregnated in the orifice plate 10, the moisture retaining property at the meniscus portion in the vicinity of the nozzle is maintained, and drying of the ink is prevented.
[0028]
Further, as shown in FIG. 6, one end of the second communication port is connected to an orifice plate and the other end is connected to a suction pump. The negative pressure sucked by the suction pump gives a negative pressure to the pores of the orifice plate, and the ink near the nozzle opening can be sucked. Here, even when printing is being performed, there are times when printing is not performed as much as possible.
[0029]
For example, in the case of a cut sheet, printing is not performed in a non-printing section between pages, and in the case of continuous paper, printing is performed at a line break such as a page break. At this time, the suction pump is operated to apply a slight negative pressure. By this negative pressure, ink in the vicinity of the nozzle, that is, the meniscus is sucked. By periodically performing this suction, it is possible to prevent the ink from being thickened at the meniscus portion due to the drying of the ink as described above.
[0030]
This makes it possible to obtain substantially the same effect as the periodic refresh operation as performed in the conventional example. In other words, it is possible to obtain the same effect as the conventional refresh operation without interrupting printing, thereby preventing a decrease in the effective printing speed of the printing apparatus.
[0031]
In the present invention, from the viewpoint of preventing foreign matter from adhering to the orifice plate 10, although capping means is necessary, the frequency of capping is lower than in the prior art. Moreover, since it is sufficient to prevent foreign matter from adhering, a relatively simple capping means can be used.
[0032]
【The invention's effect】
As described above, according to the present invention, the area around the meniscus is always moisturized, and even when the capping means is opened, ink drying can be suppressed as much as possible.
[0033]
Further, by applying a negative pressure to the porous orifice plate and periodically sucking the ink in the vicinity of the nozzle, that is, the meniscus, it is possible to prevent the ink from thickening in the meniscus portion due to the drying of the ink.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an example of a periphery of a head of an ink jet recording apparatus.
FIG. 2 is an example of a cross-sectional view of an ink jet recording head in the prior art.
FIG. 3 is a cross-sectional view showing a configuration of a first example of an ink jet recording head according to the present invention.
FIG. 4 is an enlarged view of a nozzle portion in FIG.
FIG. 5 is a configuration diagram illustrating a second example of an ink jet recording head according to the present invention.
FIG. 6 is a schematic diagram illustrating an example of an ink jet recording apparatus according to the present invention.
[Explanation of symbols]
1 is a head, 2 is a capping means, 3 is an ink absorber, 4 and 5 are suction pumps, 6 is a waste ink tank, 10 is an orifice plate, 11 is a nozzle opening, 17 is a meniscus, 18 is an ink repellent film, 20 Is an ink chamber, 21 is a common ink chamber, 22 is an ink supply port, 23 is a pressure generating chamber, 24 is a communication port, 30 is a fixing member, 40 is an ink supply tube, 41 is a second communication port, and 42 is an ink suction port. A tube, 50 is an ink cartridge, and 60 is ink.

Claims (6)

A common ink chamber that stores ink; an ink supply port that communicates with the common ink chamber; a pressure generation chamber that communicates with the ink supply port; and a plurality of nozzle openings that eject ink and record on a recording material The orifice plate is made of a porous member that can be impregnated with ink, and the surface of the orifice plate on the ink discharge port side is subjected to ink repellent treatment. An ink jet recording head. 2. The ink jet recording head according to claim 1, wherein the orifice plate seals one surface of a common ink chamber that supplies ink to each nozzle opening for ejecting ink. A common ink chamber that stores ink; an ink supply port that communicates with the common ink chamber; a pressure generation chamber that communicates with the ink supply port; and a plurality of nozzle openings that eject ink and record on a recording material The orifice plate is made of a porous member that can be impregnated with ink, and the surface of the orifice plate is subjected to a surface treatment without ink permeability. Inkjet recording head. 4. An ink jet recording head according to claim 3, further comprising an ink supply path to the common ink chamber and a second supply path for supplying moisturizing liquid or ink to the orifice plate. 5. The ink jet recording head according to claim 4, wherein one end of the second communication port is connected to an orifice plate and the other end is connected to a suction pump. 4. The ink jet recording head according to claim 3, wherein an ink chamber side surface of the orifice plate is subjected to an ink affinity process, and an ink discharge side surface is subjected to an ink repellent process.

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