JP2012162012A - Liquid injection device - Google Patents

Abstract

A technique capable of performing a flushing operation without moving an ejection head and capable of reliably collecting a liquid ejected by flushing.
The speed of a liquid (charged liquid) ejected from the ejection head is reduced by the potential difference generated between the ejection head and the ejection target medium, and the reduced liquid is sucked by the liquid suction means. . By doing so, the liquid ejected by the flushing operation can be collected, so there is no fear that the liquid adheres to the ejected medium and becomes dirty. Further, since the liquid ejected by the flushing operation can be collected, it is not necessary to move the ejection head to another position for the flushing operation. As a result, there is no misalignment that accompanies the movement of the ejection head,
It is possible to eject ink at the same position.
[Selection] Figure 4

Description

  The present invention relates to a liquid ejecting apparatus that ejects a liquid such as ink.

A so-called inkjet printer prints an image by ejecting ink onto a print medium. Since the position and amount of ink ejected can be controlled with extremely high accuracy, a high-quality image can be printed. It has also been proposed to form various functional parts such as electrodes and sensors by ejecting liquids containing various functional materials onto a substrate using this technique.

In such a liquid ejecting apparatus, the liquid is ejected by moving the position of the ejection target medium (printing medium) little by little (sub-scanning) while reciprocating (main scanning) the ejection head on the ejection target medium (printing medium). On the other hand, there is also proposed a method of ejecting liquid by moving (sub-scanning) only the ejected medium (print medium) little by little without moving the ejecting head. In the present specification, the former injection method is called “serial injection method”, and the latter injection method is called “line injection method”.

Regardless of which injection method is used, the liquid in the injection nozzle gradually increases in viscosity, so it is necessary to remove the liquid that has increased in viscosity in the injection nozzle by periodically performing liquid flushing. is there. In the serial ejection method in which the ejection head is main-scanned, a cap member is provided outside the area where the ejection medium is conveyed, and the viscosity is increased by moving the ejection head so far and ejecting liquid toward the cap member. Remove liquid. On the other hand, in the liquid ejecting apparatus of the line ejecting method, if the flushing is executed by the same method as the serial ejecting method, a positional deviation occurs when the ejecting head is returned from the position of the cap member to the original position. In some cases, it becomes impossible to eject the liquid.

Therefore, it is conceivable to perform flushing without moving the ejection head by providing a suction means next to the ejection head (Patent Document 1) and sucking the liquid ejected by flushing with the suction means.

JP 2000-255083 A

However, since the liquid is ejected at high speed during the flushing, there is a problem that it is difficult to reliably collect the ejected liquid by suction. As a result, there has been a problem that, for example, the ejected liquid may adhere to the ejection medium and contaminate the ejection medium.

The present invention has been made in order to solve at least a part of the above-described problems of the prior art, and it is possible to perform flushing without moving the ejection head, and the liquid ejected by flushing can be used. The purpose is to provide technology for reliable collection.

In order to solve at least a part of the problems described above, the liquid ejecting apparatus of the present invention employs the following configuration. That is,
A liquid ejecting apparatus that ejects liquid from an ejecting head toward an ejected medium,
Liquid charging means for charging the liquid ejected from the ejection head;
A potential difference in a direction in which the liquid ejected while being charged from the ejection head decelerates,
A potential difference generating means for generating between the ejection head and the ejection medium;
And a liquid suction means for sucking the liquid existing between the ejection head and the ejection target medium.

In such a liquid ejecting apparatus of the present invention, the speed of the liquid (charged liquid) ejected from the ejecting head is reduced by the potential difference generated between the ejecting head and the ejection target medium and then decelerated. Liquid is sucked by the liquid suction means. When charging the liquid,
For example, it may be charged using a device for charging the liquid, or may be charged by static electricity generated while the liquid moves through the passage. In addition, when a potential difference is generated between the ejection head and the ejection medium, the potential difference may be generated by applying a voltage having the same polarity as the liquid to the ejection medium side, or the liquid is generated on the ejection head side. A potential difference may be generated by applying a voltage having the opposite polarity.

In this way, by reducing the speed of the liquid ejected by the flushing operation, the suction force of the liquid suction means can sufficiently act on the liquid, so that the ejected liquid can be collected. Therefore, it is possible to avoid the ejection target medium from being contaminated by the liquid ejected during the flushing operation. Further, if the liquid ejected by the flushing operation can be collected in this manner, the ejection head does not need to be moved from the original position (position for ejecting the liquid) to another position. As a result, it is possible to prevent the displacement of the ejection head as the ejection head moves, so that it is possible to eject liquid to the same position before and after the flushing operation.

Further, in the above-described liquid ejecting apparatus of the present invention, a potential difference in the direction of decelerating the speed of the ejected liquid is provided between the ejecting head and the medium support unit that supports the ejected medium from the back side with respect to the ejecting head. It may be generated.

The ejection head and the medium support portion are provided at positions facing each other. Therefore, if a potential difference is generated between the ejection head and the medium support portion in the direction in which the liquid speed is reduced, such a potential difference can be easily generated.

Further, the liquid suction unit of the liquid ejecting apparatus of the present invention described above may suck the liquid ejected from the ejecting head from the direction in which the ejected medium is conveyed.

When the ejected medium is transported, an air flow is generated in the transport direction. Therefore, when a flushing operation is performed while transporting the ejected medium, the liquid ejected from the ejecting head moves in the transport direction by the air stream. Therefore, if the liquid is sucked from the direction in which the ejection target medium is conveyed, the liquid ejected by the flushing operation can be efficiently collected.

The above-described liquid ejecting apparatus of the present invention is a switching control that switches between a first operating state in which liquid is ejected while generating a potential difference by the potential difference generating means and a second operating state in which liquid is ejected without generating a potential difference. Means may be provided.

If such a switching control means is provided, the state in which the flushing operation is performed (that is, the first operation is performed).
It is possible to quickly switch between the operation state) and the state in which the liquid is ejected onto the ejection target medium (that is, the second operation state). Accordingly, it is possible to quickly restart the ejection of the liquid onto the ejection target medium after the flushing operation.

It is explanatory drawing which showed the rough structure of the liquid ejecting apparatus of a present Example using a line printer as an example. It is explanatory drawing which shows a state when a head unit is seen from the bottom face side. It is explanatory drawing which showed the structure of the ink collection | recovery mechanism of a present Example. It is explanatory drawing which showed a mode that the ink ejected by flushing was collect | recovered using a collection | recovery mechanism. It is explanatory drawing which showed the structure of the ink collection | recovery mechanism of a 1st modification. It is explanatory drawing which showed the structure of the ink collection | recovery mechanism of a 2nd modification. It is explanatory drawing which showed a mode that the ink ejected by flushing was collect | recovered using the ink collection | recovery mechanism of a 3rd modification.

Hereinafter, in order to clarify the contents of the present invention described above, examples will be described in the following order.
A. Device configuration:
B. Ink recovery mechanism of this embodiment:
C. Variations:
C-1. First modification:
C-2. Second modification:
C-3. Third modification:
C-4. Fourth modification:

A. Device configuration :
FIG. 1 is an explanatory diagram showing a rough structure of a liquid ejecting apparatus according to the present embodiment using a line printer 1 as an example. As shown in the drawing, the line printer 1 of the present embodiment has a box-shaped outer shape roughly, and a monitor 2 for displaying various information on the upper surface and operations for user operations. Panel 3 etc. are provided. In addition, a cartridge replacement door 4 for replacing the ink cartridge and a paper feed door 5 for loading printing paper are provided on the front surface of the line printer 1, and further, on the right side, printing is performed. A paper discharge port 6 is provided through which the printed paper is discharged.

Inside the line printer 1, a plurality of units or parts for executing various functions are mounted. First, a head unit 30 that ejects ink onto printing paper is provided at a substantially central position of the line printer 1, and a platen 40 (medium for supporting the printing paper from the back side) is located immediately below the head unit 30. Support part) is provided. A cartridge holder 60 is provided at a lower right position of the head unit 30, and an ink cartridge 62 filled with ink is attached to the cartridge holder 60. still,
In the line printer 1 of the present embodiment, the line printer 1 that performs black and white printing using black ink (K ink) is illustrated, but the line printer 1 includes cyan ink (C ink) in addition to K ink. Alternatively, the printer may perform color printing using a plurality of inks such as magenta ink (M ink) and yellow ink (Y ink).

A paper feed cassette 10 on which printing paper is loaded is provided at the lower left position of the head unit 30 on the paper surface of FIG. 1, and a paper feed roller 20 is located at a position in contact with the upper surface of the right end of the paper feed cassette 10. Is provided. A paper feed motor 22 is connected to the back side of the paper feed roller 20. When the paper feed motor 22 is driven to rotate the paper feed roller 20, one sheet of printing paper from the paper feed cassette 10 and the head unit 30. It is intended to be conveyed toward In FIG. 1, the conveyance path of the printing paper is indicated by a thick broken line.

A control unit 100 for controlling various movements of the line printer 1 is mounted at a position immediately below a portion where the monitor panel 2 and the operation panel 3 are provided. Further, the line printer 1 of the present embodiment is provided with a suction device 50 at a position on the right side of the head unit 30 on the paper surface of FIG. Although described in detail later, the line printer 1 of the present embodiment
Then, when an operation (flushing operation) of ejecting ink from the head unit 30 is performed for the purpose of removing the thickened ink in the head unit 30, the ejected ink is collected by the suction device 50. ing.

Next, the printing operation of the line printer 1 of the present embodiment will be described with reference to FIG. First, the printing paper taken out from the paper feed cassette 10 by the paper feed roller 20 is guided by a guide roller 24 provided between the paper feed roller 20 and the head unit 30 and below the head unit 30 (that is, the platen 40). To the top). Head unit 3
No. 0 is provided on the printing paper transport path so as to straddle the printing paper, and an ejection head (see FIG. 2) is provided on the bottom side of the head unit 30 (the side facing the printing paper). It has been. Ink is supplied to the head unit 30 from an ink cartridge 62 mounted on the cartridge holder 60 via an ink passage (not shown).
Ink is ejected from the ejection head provided at 0 toward the printing paper.

FIG. 2 is an explanatory view showing a state when the head unit 30 is viewed from the bottom side. As shown in the drawing, an elongated substantially rectangular ejection head 32 is provided on the bottom surface of the head unit 30 of this embodiment, and the ejection head 32 has a plurality of ejection nozzles that eject ink. Is provided. Note that the surface of the ejection head 32 provided with the ejection nozzles may be referred to as a “nozzle surface”.

When ink is ejected from the head unit 30 provided with the ejection head 32 in this way, an image is printed on the printing paper that is passing through the conveyance path shown in FIG. The printing paper on which the image is printed in this manner is guided by a guide roller 24 provided on the downstream side of the head unit 30 and is discharged out of the line printer 1 from the paper discharge port 6. Further, as described above, the line printer 1 of this embodiment is provided with the following mechanism for the purpose of collecting the ink ejected from the head unit 30 by the flushing operation.

B. Ink recovery mechanism of this embodiment:
FIG. 3 is an explanatory diagram showing a configuration of a mechanism for collecting ink ejected by the flushing operation. FIG. 3 shows a longitudinal section of the configuration around the head unit 30 when the line printer 1 shown in FIG. 1 is viewed from the front.

The ink recovery mechanism of the present embodiment is roughly based on a suction device 50 (liquid suction means) provided on the right side of the head unit 30 on the paper surface of FIG. 3, a mechanism provided on the platen 40 side, and the like. Composed. The suction device 50 is provided on the suction port 52 that opens toward the platen 40, the waste ink passage that connects the suction port 52 and a waste ink container (not shown), or the waste ink passage, and applies to the suction port 52. For example, a negative pressure pump 54 for generating a negative pressure for the purpose. As shown in FIG. 3, the suction device 50 is grounded by wiring.

The platen 40 is connected to a power source 70 (potential difference generating means) via a switch 72. In such a mechanism on the side of the platen 40, the switch 72 is turned on to turn on the platen 40.
When a voltage (a negative voltage in this embodiment) is applied to the platen, a positive charge is induced on the grounded suction device 50 side, and a negative charge is induced on the platen 40.

FIG. 4 is an explanatory view showing a state in which the ink ejected by the flushing operation is collected by the collection mechanism of the present embodiment. In the line printer 1 of the present embodiment, during printing, the negative pressure pump 54 of the suction device 50 described above is stopped and the switch 72 between the platen 40 and the power supply 70 is turned off (see FIG. 3). In this state, ink is ejected from the ejection nozzle toward the printing paper, thereby printing an image on the printing paper.

On the other hand, when the ink viscosity increases in the ejection nozzle and it becomes necessary to perform the flushing operation, first, as shown in FIG. 52
The suction is started, and the switch 72 is turned on to apply a negative voltage to the platen 40. Here, in the line printer 1 of this embodiment, the ink is charged to a negative charge by static electricity while the ink moves to the ejection head 32 through the ink passage 64. For this reason, as shown in FIG. 4B, when the flushing operation is performed with a negative voltage applied to the platen 40, the ink speed is reduced by the electric repulsive force.
Ink is sucked into the suction device 50 by the suction force from the suction port 52 reaching the ink thus decelerated. As a result, all the ink ejected by the flushing operation can be collected. In addition, since the ink ejected by the flushing operation can be prevented from adhering to the platen 40, the printing paper conveyed on the platen 40 is not soiled. Further, during the flushing operation, a potential difference is generated between the platen 40 and the suction device 50 (see FIG. 3), and a voltage in the direction in which the suction device 50 sucks ink is applied. An electric attractive force is provided to be collected by the suction device 50.

As described above, in the line printer 1 of the present embodiment, all the ink ejected by the flushing operation can be collected, and therefore it is not necessary to move the head unit 30 to another position when executing the flushing operation. As a result, since it is not necessary to perform flushing toward the cap member after the head unit 30 is moved to the position of the cap member, the head unit 30 is not displaced with the movement of the head unit 30. For this reason, ink can be ejected to the same position before and after the flushing operation.

Further, in the ink collecting mechanism of the present embodiment, the suction device 50 is disposed on the downstream side of the printing paper conveyance path as viewed from the head unit 30. For this reason, for example, if the flushing operation is performed while transporting a portion of the printing paper on which no image is printed, the ink can be moved in the direction of the suction device 50 by the airflow generated in the transport direction. As a result, the ink ejected by the flushing operation can be more easily collected.

C. Modified example:
Several modifications can be considered in the above-described embodiment. Hereinafter, these modified examples will be briefly described. Note that, in the modification described below, the same components as those in the above-described embodiment are denoted by the same reference numerals as those in the embodiment, and detailed description thereof is omitted.

C-1. First modification:
In the above-described embodiment, it has been described that the ink ejected from the ejection nozzle is charged by static electricity while the ink moves to the head unit 30 through the ink passage 64. Here, for the purpose of charging the ink more reliably, the line printer 1 may be provided with a mechanism for charging the ink.

FIG. 5 is an explanatory diagram showing the configuration of the ink collection mechanism of the first modification. In the illustrated recovery mechanism, a charging device 34 for charging the ink passing through the internal passage to a negative charge is provided in the middle of the internal passage of the head unit 30 reaching the ejection head 32. If such a charging device 34 is provided, the ink ejected from the ejection nozzle can be reliably charged, and therefore the ink ejection speed can be reliably reduced by the electric repulsive force from the platen 40. it can. As a result, the ink can be sucked with a relatively small suction force, so that the negative pressure pump 54 can be downsized, and the suction device 50 can be downsized.

C-2. Second modification:
In the above-described embodiment and the first modification, it has been described that the negative pressure pump 54 of the suction device 50 is driven when performing the flushing operation. However, the negative pressure pump 54 may be always driven while the line printer 1 is in operation (that is, in a power-on state).

A certain amount of time is required from the start of driving of the negative pressure pump 54 until the ink can actually be sucked by the suction device 50. Therefore, if the negative pressure pump 54 is always driven, the flushing operation can be started quickly only by charging the platen 40 to a negative voltage when performing the flushing operation. Also, the negative pressure pump 54
If the suction force of the suction device 50 is adjusted so as not to affect the ejection of ink during printing by adjusting the magnitude of the negative pressure generated in step 1, the print image quality is not deteriorated by suction.

C-3. Third modification:
In the second modification described above, it has been described that the flushing operation can be started quickly by always driving the negative pressure pump 54 while the line printer 1 is in operation. here,
When adopting a configuration in which the negative pressure pump 54 is always driven, the following configuration may be added to the line printer 1.

FIG. 6 is an explanatory diagram showing a configuration around the head unit 30 of the line printer 1 of the third modified example. In the line printer 1 of the third modified example shown in the figure, a power supply 74 for applying a positive voltage to the platen 40 via the switch 76 is added to the platen 40 of the line printer 1 described above with reference to FIG. ing. In such a line printer 1,
When ink is ejected toward the printing paper, a positive voltage can be applied to the platen 40 by turning on the switch 76. In this way, the ink ejected from the ejection nozzle can be reliably guided in the direction of the printing paper. Therefore, even when the configuration in which the negative pressure pump 54 is always driven as described above is employed, it is not necessary to suppress the suction force of the suction device 50 in consideration of the influence on the ejected ink. As a result, it is possible to collect the ink ejected with a sufficient suction force while allowing the flushing operation to be started quickly.

C-4. Fourth modification:
In the above-described embodiments and modifications, it has been described that the ejection speed of the ink ejected by the flushing operation is reduced by charging the platen 40 to a negative voltage. Here, as a configuration for decelerating the ink ejection speed, the following configuration is also conceivable.

FIG. 7 is an explanatory diagram showing the configuration of the ink collection mechanism of the fourth modified example. In the ink recovery mechanism of the fourth modification shown in FIG. 7A, as described above, the power supply 7 is connected to the platen 40.
Instead of adopting a configuration in which a voltage of 0 is applied (see FIG. 3), the injection nozzle and the platen 40
The voltage of the power source 70 is applied to the shutter member 82 of the shutter mechanism 80 that can be opened and closed.

In the ink collecting mechanism configured as described above, when the shutter member 82 is retracted outside the ink ejection path during printing and a flushing operation is performed, the shutter is moved as shown in FIG. A negative charge is induced in the shutter member 82 with the member 82 deployed. Thereby, similarly to the case described above with reference to FIG. 3, the speed of the ink ejected by the flushing operation can be reduced by the electric repulsive force. In the ink recovery mechanism shown in FIG. 7, the shutter member 82 blocks the ejection nozzle from the platen 40 during the flushing operation. Therefore, even when the negative pressure pump 54 fails or when a mechanism for applying a voltage to the shutter member 82 fails, the collected ink is received by the shutter member 82. be able to.
As a result, it is possible to more reliably avoid contamination of the platen 40 by the ejected ink.

As mentioned above, although the Example of this invention was described, this invention is not limited above,
The present invention can be implemented in various modes without departing from the gist thereof. For example, in the above-described embodiments and modifications, it has been described that a negative voltage is applied to the platen when performing the flushing operation. However, the voltage applied to the platen may be a voltage having the same polarity as the charge of the ink. If the charge of the ink is positive, the voltage applied to the platen may be positive.

In the above-described embodiments and modifications, it has been described that a voltage having the same polarity as the ink is applied to the platen side. However, for example, a voltage having a polarity opposite to that of the ink is applied to the ejection head side. May be. In this way, the ink speed can be reduced by pulling back the ink ejected during the flushing operation in the direction opposite to the ink ejection direction (that is, the direction of the ejection head). As a result, the ink can be easily collected by the suction device as in the case where a voltage having the same polarity as the ink is applied to the platen side.

1 ... Line printer, 30 ... Head unit, 32 ... Ejecting head,
34 ... Charging device, 40 ... Platen, 50 ... Suction device,
52 ... Suction port, 54 ... Negative pressure pump, 62 ... Ink cartridge,
64 ... ink passage, 70 ... power supply, 72 ... switch,
74 ... Power supply, 76 ... Switch, 80 ... Shutter mechanism,
82 ... Shutter member, 100 ... Control unit

Claims (4)

A liquid ejecting apparatus that ejects liquid from an ejecting head toward an ejected medium,
Liquid charging means for charging the liquid ejected from the ejection head;
A potential difference in a direction in which the liquid ejected while being charged from the ejection head decelerates,
A potential difference generating means for generating between the ejection head and the ejection medium;
A liquid ejecting apparatus comprising: a liquid sucking unit that sucks the liquid existing between the ejecting head and the ejected medium. The liquid ejecting apparatus according to claim 1,
A medium support part for supporting the ejection medium from the back side with respect to the ejection head;
The liquid ejecting apparatus, wherein the potential difference generating unit is a unit that generates the potential difference between the ejecting head and the medium support unit. The liquid ejecting apparatus according to claim 1 or 2,
Medium transport means for transporting the ejected medium in a predetermined direction from a position at which the liquid is ejected;
The liquid ejecting apparatus, wherein the liquid sucking unit is a unit that sucks the liquid from a direction in which the ejected medium is conveyed. The liquid ejecting apparatus according to any one of claims 1 to 3,
A first operation state in which the liquid is ejected while generating the potential difference using the potential difference generation means; and a second operation state in which the liquid is ejected without generating the potential difference by stopping the operation of the potential difference generation means. A liquid ejecting apparatus comprising switching control means for switching between the two.

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