JPH0626891B2 - Liquid ejector - Google Patents

Description

The present invention relates to a liquid ejecting apparatus, and more particularly to a liquid ejecting apparatus including a droplet ejection recovery unit.

In recent years, the non-impact recording method has been attracting attention because the noise generated during recording is extremely small. Among them, the liquid jet recording method in which flying droplets are deposited on a recording member to perform recording can perform recording without requiring special processing such as so-called fixing on plain paper, and can also perform high-speed recording. Is attracting attention.

In addition, since the liquid jet recording method ejects liquid droplets from a fine orifice, the foreign matter such as paper dust is caught in the orifice to stop the ejection of droplets, or the recording liquid ( Since the solvent in the liquid) evaporates, the solute remaining in the orifice or in the vicinity thereof may become an obstacle and the discharge of the droplet may be stopped. In addition, the dissolved gas in the liquid may not be present continuously from the liquid reservoir storing the liquid to the orifice due to the gas generated by being released from the liquid and entering due to other causes. Atsuta When that happens,
In some cases, the energy for ejecting the droplets from the orifice is not transmitted to the liquid, or even if the energy is transmitted, the droplets are not ejected or the ejection becomes unstable. Further, if unnecessary gas is present, the liquid may not be supplied in proportion to the amount of liquid discharged due to the gas.

Among the above, in the liquid jet recording apparatus, non-ejection of droplets due to clogging of the orifice or the liquid flow path communicating with the orifice is an important problem, and various proposals have been made as countermeasures against it.

Moreover, as described above, various reasons may be considered as the cause of clogging, and it is necessary to take countermeasures according to the cause. One of the causes of such non-ejection is considered to be an increase in ejection resistance due to thickening of the ink due to evaporation of the low boiling point substance of the ink near the ink ejection holes. In such a case, as a countermeasure against this, a method in which a porous body is brought into close contact with the ink ejection holes and the thickened ink is absorbed by the porous body is effective. However, in such a method, the absorbed ink saturates the porous body, which requires frequent replacement of the porous body.

Further, there are cases where the liquid is not absorbed by the porous body due to the increase in the viscosity of the liquid or the evaporation of the solvent. That is, although the above-described means for recovering liquid droplet ejection is excellent as a preventive means for preventing liquid non-ejection and a measure for mild clogging, foreign matter is clogged or a large amount of gas enters the liquid flow path. In some cases, it was not possible to eliminate the causes of severe clogging and severe ejection failure, such as when rubbed in.

As a means to eliminate the cause of non-ejection of equal severity, the orifice surface of the recording head is capped with a cap, and the inside of the cap is sucked using a suction means that generates a suction force.
Means for eliminating the cause of non-ejection by sucking out gas are known. However, in this case, it is difficult to balance the suction force and the force for removing the cause of non-ejection of droplets, and air bubbles may be generated due to the cavitation during the recovery operation.

In addition, when the porous body is brought into contact with an orifice surface having a plurality of orifices for recovery, the thickened liquid sucked into the porous body is unevenly distributed in the porous body. As a result, suction recovery of only some of the orifices is performed, while suction recovery of other orifices in a region where the thickened liquid is largely distributed may be insufficient. In addition, air bubbles may be generated due to cavitation caused in the liquid flow path communicating with the above-mentioned partial orifice in which suction is performed due to a drop in pressure due to excessive suction.

That is, even though the operation for recovering the ejection of the droplets is performed, the cause of the failure or the inability of the droplet ejection is generated, or the sucked liquid remains near the orifice and the ejection of the droplets is performed. There is a case where the conventional recovery means may cause the instability.

Also, in the case of recovery by suction, when there is no liquid in the liquid chamber, when the recovery means is released from the orifice surface while the recording head side is depressurized, the atmosphere flows back from the atmosphere side and no recovery operation is performed. I got it. Furthermore, if a filter is installed to prevent foreign matter in the liquid from clogging the orifice surface, when the atmosphere reaches the filter, the atmosphere (air) will enter the filter, and the discharge characteristics after that will be a major obstacle. In some cases, there were serious drawbacks.

〔Purpose〕

The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid ejecting apparatus equipped with a recovery means capable of controlling suction force with a simple configuration. It is also an object of the present invention to provide a liquid ejecting apparatus equipped with a recovery means that ensures recovery of droplet ejection.

Still another object of the present invention is to provide a liquid jet recording apparatus which realizes a long life of the porous body as described above and is provided with a highly reliable means for recovering droplet discharge.

Still another object of the present invention is to remove the thickened liquid adhering to the vicinity of a plurality of orifices while preventing bubbles from being generated in the liquid in the liquid channel due to cavitation, and to recover the droplet discharge of the plurality of orifices. Another object of the present invention is to provide a liquid ejecting apparatus equipped with a recovery means capable of reliably performing the above.

According to the present invention, a porous body, which is in contact with an orifice surface provided with a plurality of orifices for ejecting a liquid that forms flying droplets, is disposed inside, a cap for capping the orifice, and the cap via the cap are provided. Suction means for sucking the liquid from the orifice, and when the pressure in the cap becomes smaller than a predetermined value due to the suction force generated by the suction means, the atmosphere is introduced into the cap, and by the introduction, the inside of the cap Suction force adjusting means for stopping the introduction of the atmosphere into the cap when the pressure becomes larger than a predetermined value, and suctioning the liquid droplets in the porous body in the cap by the suction force adjusting means. Another object of the present invention is to provide a liquid ejecting apparatus that performs introduction of air into and out of the atmosphere.

The liquid ejecting apparatus provided by the present invention is an apparatus having a plurality of orifices for forming flying droplets, and is preferably used for forming a liquid flow path communicating with the orifices and flying droplets. And an energy generator that generates the generated energy.

〔Example〕

 The present invention will be described below with reference to preferred embodiments.

FIG. 1 is a schematic perspective partial view for explaining a liquid jet recording apparatus of the present invention. As shown in FIG. 1, in this embodiment, a carriage driving belt 7 is provided on the recording paper 1 which is moved on the platen 2 in the sub-scanning direction (direction of arrow A) by the paper feed roller 3 and the pinch roller 4. Droplets from a multi-nozzle head unit 9 to 12 (hereinafter referred to as a head) fixed via a head door liner 8 to a carriage 5 which is moved along a guide shaft 6 in the main scanning direction (direction of arrow B). Is an example of performing printing by ejecting in accordance with an input signal. Each of the heads 9 to 12 has a liquid chamber 13, and each of the liquid chambers 13 is connected to an ink pipe 15 to 18 communicating with an ink tank (not shown) via a coupler 14. Further, the flexible wiring 19 is connected to each of the heads 9 to 12, and an electric signal for ejecting a droplet is input by this.

22 to 25 are porous bodies and are held by the cap 21, which is also a porous body holder, and fixed to the duct 27 via the elastic support body 26. A suction pipe 28 having one end connected to a suction means 29 for generating a suction force is connected to the duct 27. Also, the duct 27 is the duct 27.
Is fixed to the substrate 30 holding the. Sachet pipe 2
A suction force adjusting means 37 is attached to the device 8. In addition, duct 2
7 is movable together with the porous bodies 22 to 25 in the direction of arrow C shown in FIG.

The recovery operation in this embodiment is performed as follows. First, the carriage 5 is detected by the sensor 23 to reach a predetermined position, the carriage 5 is stopped, and the duct 27 is moved toward the carriage 5, whereby the porous bodies 22 to 25 are attached to the orifice surface of each head. Make them adhere to each other. Next, the suction means 29 is operated to generate a suction force to suck the liquid or gas absorbed by the porous body. At this time, when a suction force that may cause the above-described non-ejection of droplets acts on the cap 21, suction force adjusting means 37 attached to the suction pipe 28 in this embodiment works and the suction pipe 28 operates.
Introduce the atmosphere into. Then, the suction force decreases due to the introduction of the atmosphere, so that the cause of non-ejection is prevented. When the suction force acting in the cap 21 decreases due to the introduction of the atmosphere, the introduction of the atmosphere is stopped. This operation of the suction force adjusting means 37 is repeated while the suction force is working. After that, the operation of the suction means 29 is stopped, and the duct 27 is separated from the carriage 5. That is, the cap 21 is removed from the heads 9 to 12.

In this embodiment, the recovery of droplet discharge is performed as described above.

An example of the recovery means in the liquid jet recording apparatus according to the present invention will be described in more detail with reference to the head 9 shown in FIG. 1 as an example. FIG. 2 is a schematic partial sectional view of the head 9 when a recovery operation is performed. The numbers shown by the lead lines in FIG. 2 are the same as the numbers shown in FIG.

As shown in FIG. 2, a waste liquid reservoir 33 is formed on the cap 21 holding the porous body 22. In addition, a hole 32 is provided in at least a suction means side of a portion where the porous body 22 and the cap 21 are in contact with each other so that a suction force acts on the porous body 22.

The duct 28 is moved in the direction of arrow C shown in FIG. 1 by pushing the cam follower 36 fixed to the base plate 30 by the eccentric cam 35 that rotates together with the shaft 31 rotated by a motor or the like. As a result, the porous body 22 is pressed against the head 9. At that time, the elastic support member 26 is slightly compressed to give an appropriate pressing force to the porous member 22. And the porous body 22
Adheres to the orifice surface of the head 9 and absorbs the liquid near the orifice.

By operating the suction means in that state, the porous body 2
The back surface of 2 is negatively pressured. The liquid absorbed in the porous body 22 is guided to the back through the continuous foaming holes of the porous body 22,
The liquid saturated on the back surface is stored in the waste liquid reservoir 33. The suction force adjusting means 37 repeats the operation described in FIG. 1 while the suction force is generated.

FIG. 3 and FIG. 6 (b) are schematic sectional views showing a preferred embodiment of the suction force adjusting means in the present invention. Third
In FIG. 6 and FIG. 6 (b), 101 is a valve body, 102 is a suction pipe, and 103 is an elastic body.

The valve elements 101 shown in FIGS. 5 to 6 (b) are respectively valve elements 1
01 itself has an elastic force, and also functions as the elastic body 103 shown in FIGS. 3 and 4.

Each valve body 101 of FIGS. 3 to 6 (b) is a suction pipe 1
The suction force in 02 pulls the inside of the suction pipe 102 to connect the atmosphere with the inside of the suction pipe 102. The elastic body is appropriately selected so as to have a force that operates when a predetermined suction force is generated in the suction pipe 102.

Incidentally, FIG. 6 (b) shows a state when the valve body 101 shown in FIG. 6 (a) is introducing the atmosphere.

Incidentally, FIG. 1 shows a liquid jet recording apparatus having a plurality of heads.
The number may be more or less than the number, and of course, the number may be singular. However, when a plurality of heads are provided, the holder and the elastic support are provided for each head in order to evenly adhere the porous body to each other's head or to prevent the ink in each head from mixing. It is preferable that each is independent. Further, the elastic support is not always necessary, but it is preferable to provide it in order to effectively transmit the suction force generated by the suction means to the porous body or to enhance the adhesion between the porous body and the head.

It is preferable that the porous body is a continuously foamed elastic body and is made of a material that easily adapts to a liquid. It is also preferable that the porous body has appropriate elasticity.

As the elastic support, a closed-cell type with little air circulation, for example, a so-called rubber having appropriate softness is preferably used.

Although FIG. 2 shows an example of using the eccentric cam as a method for moving the duct 31, it is needless to say that the duct 31 can be moved by various methods other than the eccentric cam.

Further, the recovery operation may be performed when the carriage comes to the home position without providing a mechanism for stopping the carriage at a predetermined position.

Although the suction force adjusting means is provided in the suction pipe in the present embodiment, it is not necessary to provide it separately here. It may be provided between the suction means that generates the suction force and the cap. That is, it may be attached to a place where the suction force generated by the suction means can be adjusted with a sufficient response.

[Effect]

As described above in detail, according to the present invention, since the life of the porous body that absorbs the liquid is remarkably extended, it is not necessary to replace the porous body for a much longer period than in the past. Therefore, the management and economic burden of the porous material is greatly reduced.
Also, by setting the suction force generated by the suction means to an appropriate size, the liquid by the orifice can be sucked,
Not only can the liquid adhering to the vicinity of the orifice be removed, but also clogging in the liquid flow path can be eliminated. Further, unlike the conventional device provided with a means for removing the clogging by suction, the porous body absorbs the excess liquid, so that the liquid does not adhere to the vicinity of the orifice and the ejection cannot be stabilized.

Further, by further repeating the introduction of the atmosphere into the cap and the suspension of the introduction of the atmosphere by the suction force adjusting means, the uneven distribution of the thickened liquid sucked into the porous body in the porous body is eliminated, and the orifice It is possible to remove the thickened liquid adhering to the vicinity of the plurality of orifices and to reliably perform the ejection recovery of the plurality of orifices, while preventing the generation of bubbles due to cavitation in the liquid in the liquid flow path related to.

That is, since the liquid jet recording apparatus of the present invention is provided with a very excellent means for recovering droplet discharge, it is possible to always perform excellent recording even when it is used for a long period of time.

[Brief description of drawings]

1 and 2 are each a view for explaining a preferred embodiment of the present invention, FIG. 1 is a schematic perspective view, and FIG. 2 is a schematic sectional view. 3 to 6 are sectional views showing a preferred embodiment of the suction force adjusting means used in the liquid jet recording apparatus of the present invention. 1 ... Recording paper, 2 ... Platen, 3 ... Paper feed roller, 4 ... Pinch roller, 5 ... Carriage, 6 ...
Guide shaft, 7 ... Carriage drive belt, 8 ... Head door liner, 9, 10, 11, 12 ... Head, 13 ... Liquid chamber, 14 ... Coupler, 15, 16, 17, 18 ... Ink pipe, 19: Flexible wiring, 20: Sensor, 2
1 ... Cap, 22, 23, 24, 25 ... Porous body, 26 ...
... elastic support, 27 ... duct, 28, 102 ... suction pipe, 29 ... suction means, 30 ... substrate, 31 ...
… Shaft, 32… Hole, 33… Waste liquid reservoir, 34… Frame, 3
5 ... Eccentric cam, 36 ... Cam follower, 37 ... Suction force adjusting means, 101 ... Valve body, 103 ... Elastic body

Claims (3)

[Claims] 1. A cap for capping the orifice, wherein a porous body, which is in contact with an orifice surface having a plurality of orifices for ejecting a liquid that forms flying droplets, is disposed inside, and a cap that caps the orifice. Suction means for sucking the liquid from the orifice, and when the pressure in the cap becomes smaller than a predetermined value due to the suction force generated by the suction means, the atmosphere is introduced into the cap, and by the introduction, the inside of the cap Suction force adjusting means for stopping the introduction of the atmosphere into the cap when the pressure of the cap becomes larger than a predetermined value, and the suction force adjusting means sucks liquid droplets in the porous body by the suction force adjusting means. A liquid ejecting apparatus, which is performed by introducing air into the interior and stopping the introduction of the atmosphere. 2. The liquid ejecting apparatus according to claim 1, wherein the suction force adjusting means is a valve. 3. The liquid ejecting apparatus according to claim 1, wherein a plurality of the caps are provided.