JP2002036576A - Liquid jet device and head cleaning method therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To clean the recording head of a liquid jet device with high reliability. SOLUTION: A head part 20 having a plurality of nozzle orifices 65 for ejecting liquid drops, a liquid housing part 7 housing the liquid supplied to the head part 20 and reciprocally moved along with the head part 20 and a cleaning mechanism 30 for cleaning the head part 20 are provided. The cleaning mechanism 30 has the cap member 31 pressed to the nozzle forming surface of the head part 20 when the head part 20 is cleaned to form a hermetically closed space between the nozzle forming surface and the cap member, a suction pump 32 for reducing the pressure in the hermetically closed space and an additive supply means 33 for adding an additive, which assists cleaning, to the hermetically closed space to mix the same with the liquid discharged to the hermetically closed space from a plurality of the nozzle orifices 65. The additive supply means 33 has an additive flow channel 34 piercing the cap member to be opened to the hermetically closed space at one end thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid ejecting apparatus for ejecting liquid droplets from a plurality of nozzle openings and a head cleaning method in the same.

[0002]

2. Description of the Related Art Ink jet recording apparatuses, which are one type of liquid ejecting apparatuses, have relatively low noise during printing and can form small dots at a high density. It is used.

[0003] Such an ink jet recording apparatus is generally equipped with an ink jet recording head mounted on a carriage and reciprocating in the width direction of the recording paper, and a paper for moving the recording paper in a direction perpendicular to the scanning direction of the recording head. A feeding unit is provided, and printing is performed by ejecting ink droplets from a printing head onto a printing sheet in accordance with print data. Then, on the carriage, for example, a recording head capable of discharging ink of each color of black, yellow, cyan, magenta is mounted, and not only text printing with black ink, but also full color printing by changing the discharge ratio of each ink. It is possible.

Such a recording head performs printing by discharging ink pressurized in a pressure generating chamber by a pressure generating element such as a piezoelectric vibrator or a heating means from a nozzle opening to a recording sheet as ink droplets. Printing failure may occur due to an increase in ink viscosity due to evaporation of the solvent from the opening, solidification of the ink, adhesion of dust, and mixing of air bubbles. For this purpose, the ink jet recording apparatus is provided with a cap member for sealing the nozzle opening of the recording head during non-printing, and a wiping member for cleaning the nozzle forming surface as necessary.

The cap member not only functions as a lid for preventing the ink from being dried at the nozzle opening, but also seals the nozzle forming surface with the cap member when the nozzle opening is clogged. The negative pressure from the suction pump causes the ink to be sucked and discharged from the nozzle opening to function as a cleaning mechanism for eliminating clogging of the nozzle opening and ink ejection failure due to air bubbles entering the ink flow path.

[0006] The process of forcibly sucking and discharging ink to eliminate clogging of the recording head and mixing of air bubbles into the ink flow path is called a cleaning operation. This is executed when printing is resumed later or when the user operates the cleaning switch after recognizing a defective printing state.After the ink is sucked and discharged from the recording head, the wiping member made of an elastic plate such as rubber is used. Then, an operation of wiping the nozzle forming surface of the recording head is performed.

[0007] The recording head also has a function of applying a drive signal unrelated to printing to eject ink droplets, which is called a flushing operation. This operation recovers an irregular meniscus generated near the nozzle opening of the recording head by the wiping operation by the wiping member during the cleaning operation, and also performs color mixing by slightly sucking the ink discharged to the cap member at the nozzle opening during the cleaning operation. Or at the nozzle opening where the ejection of ink droplets is small during printing.
This operation is performed at regular intervals in order to prevent clogging due to thickening of ink.

[0008]

However, in the above-described conventional cleaning mechanism, there is a problem that the ink discharged from the nozzle opening is agitated by the air flow due to the negative pressure inside the cap member, and bubbles are generated. . These bubbles are taken into the inside of the nozzle opening or adhere to the vicinity of the nozzle opening to cause unstable ejection. In order to prevent the ejection instability from being induced by such cleaning, various devices have been devised in the cleaning sequence and the structure around the cap member (Japanese Patent Laid-Open No. 7-276671 and Japanese Patent Laid-Open No.
0-202908 and JP-A-11-115212).

Further, when ink having a strong clogging property is used, even if the suction pump is rotated to make the inside of the cap member a negative pressure, it is difficult to suck the ink. Operation was required in some cases. Therefore, some measures have been taken to improve the reliability of cleaning (see JP-A-11-58776).

[0010] The reliability of cleaning is closely related to the ink composition, and the type and amount of additives to be added to the ink in order to suppress foaming and clogging have been devised (Japanese Patent Application Laid-Open No. Hei 9 (1998) -108). -268266).

However, if an additive is added to the ink in order to improve the reliability of cleaning, the use of the additive is naturally restricted because the properties such as printing stability and color developability may be deteriorated. However, sufficient reliability could not always be obtained.

Further, the ink jet technology is a technology applied not only to printing on paper, but also to various manufacturing processes using the printing technology, and the discharged liquid is not limited to dye ink and pigment ink. It has a great potential for future development. For this reason, it is required to perform cleaning on various liquids with high reliability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a liquid ejecting apparatus and a liquid ejecting apparatus capable of performing head section cleaning with high reliability. And to provide a head cleaning method.

[0014]

In order to solve the above-mentioned problems, a liquid ejecting apparatus according to the present invention comprises a head having a plurality of nozzle openings from which liquid droplets are ejected, and a liquid supplied to the head. A liquid storage unit that stores and reciprocates integrally with the head unit; and a cleaning mechanism for cleaning the head unit, wherein the cleaning mechanism includes a nozzle of the head unit when cleaning the head unit. A cap member pressed against a forming surface to form a sealed space with the nozzle forming surface, a suction pump for creating a negative pressure in the sealed space, and an additive for assisting cleaning, supplied to the sealed space Additive supply means for mixing the liquid discharged into the closed space from the plurality of nozzle openings, and the additive supply means, the cap member One end through is characterized by having an additive channel opening into the enclosed space.

[0015] Preferably, the additive supply means includes a flow control valve provided in the middle of the additive flow path;
A control unit that controls a flow rate of the additive discharged into the closed space by adjusting an opening degree of the flow control valve.

Preferably, the additive is discharged into the closed space from an end opening of the additive flow path by applying a negative pressure to the closed space.

Preferably, the additive has at least one of a defoaming effect on the liquid discharged into the closed space and a re-dissolving effect on the liquid fixed in the nozzle opening.

[0018] Preferably, the liquid ejected from the plurality of nozzle openings is ink.

In order to solve the above-mentioned problems, the present invention provides a head unit having a plurality of nozzle openings from which droplets are ejected,
A liquid container that contains the liquid supplied to the head unit and reciprocates integrally with the head unit.In a head cleaning method for a liquid ejecting apparatus, a cap member is pressed against a nozzle forming surface of the head unit. Forming a closed space between the nozzle forming surface and the cap member by applying pressure, a step of applying a negative pressure to the closed space, and an additive penetrating the cap member and opening one end to the closed space. Via a flow path, a step of supplying an additive for assisting cleaning to the closed space and mixing the additive with the liquid discharged into the closed space from the plurality of nozzle openings. I do.

[0020] Preferably, the flow rate of the additive discharged into the closed space is controlled by adjusting the opening of a flow control valve provided in the middle of the additive flow path.

Preferably, the additive is discharged into the closed space from an end opening of the additive flow path by applying a negative pressure to the closed space.

Preferably, the additive has at least one of a defoaming effect on the liquid discharged into the closed space and a re-dissolving effect on the liquid fixed in the nozzle opening.

Preferably, the liquid ejected from the plurality of nozzle openings is ink.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid ejecting apparatus according to an embodiment of the present invention will be described with reference to the drawings. The liquid ejecting apparatus according to the present embodiment is an ink jet recording apparatus that ejects ink droplets from nozzle openings of a recording head (head unit). In FIG. 1, reference numeral 1 denotes a carriage. The carriage 1 is configured to be reciprocated in the axial direction of a platen 5 while being guided by a guide member 4 via a timing belt 3 driven by a carriage motor 2. .

An ink jet recording head, which will be described later, is mounted on the side of the carriage 1 facing the recording paper 6, and an ink cartridge 7 for supplying ink to the recording head is detachably mounted on the upper portion thereof.

A cap member 31 is disposed at a home position (right side in the drawing), which is a non-printing area of the recording apparatus. The cap member 31 moves the recording head mounted on the carriage 1 to the home position. At times, the recording head is pressed against the nozzle forming surface to form a closed space between the recording head and the nozzle forming surface. The cap member 31 is located below the cap member 31.
A pump unit 10 for applying a negative pressure to the closed space formed by the above is disposed.

The cap member 31 functions as a lid for preventing the nozzle opening of the recording head from drying during the suspension of the recording apparatus, and also applies a drive signal unrelated to printing to the recording head to empty ink droplets. It functions as an ink receiver at the time of a flushing operation for discharging, and also functions as a cleaning mechanism that suctions and discharges ink by applying a negative pressure from a suction pump (described later) constituting the pump unit 10 to the recording head.

In the vicinity of the cap member 31 on the printing area side, a wiping means 11 having an elastic plate such as rubber is disposed so as to be able to advance and retreat in a horizontal direction, for example, with respect to the movement locus of the recording head. When the carriage 1 reciprocates toward the cap member 31, the nozzle forming surface of the recording head can be wiped as necessary.

FIG. 2 is a longitudinal sectional view showing a recording head provided with a piezoelectric vibrator in a longitudinal vibration mode in the liquid ejecting apparatus according to the present embodiment, and FIG. 3 is a cross-sectional view taken along line AA of FIG. FIG.

As shown in FIG. 2, the recording head (head portion) 20 includes a flow path forming substrate 60 and a nozzle plate 61 disposed on the surface 60a side of the flow path forming substrate 60.
And a case member 62 disposed on the back surface 60b side of the flow path forming substrate 60, and a flow path sealing plate 63 disposed between the rear surface 60b of the flow path forming substrate 60 and the case member 62. .

The flow path forming substrate 60 includes a plurality of pressure generating chambers 6.
The nozzle plate 61 has a plurality of nozzle openings 65 communicating with the plurality of pressure generating chambers 64. The flow path forming substrate 60 further includes a reservoir 66 for storing the ink supplied to each pressure generating chamber 64.
Are formed, and each pressure generating chamber 64 communicates with the reservoir 66 via each ink supply port 67 formed corresponding to each pressure generating chamber 64. The ink supply port 67 has a function of regulating the flow rate of ink between the reservoir 66 and the pressure generating chamber 64. The upper openings of the pressure generating chamber 64, the ink supply port 67, and the reservoir 66 are sealed by the flow path sealing plate 63.

A plurality of piezoelectric vibrators 68 arranged corresponding to the plurality of pressure generating chambers 64 are housed inside the case member 62, and each of the piezoelectric vibrators 68 is attached to the case member via a mounting portion 69. It is fixed to 62.

The flow path sealing plate 63 includes a plurality of piezoelectric vibrators 68.
And a vibrating plate 73 including an elastically deformable region 72 formed around the island-shaped portion 70. In addition, the diaphragm 73 has
Also, as shown in FIG. 3, a compliance portion 74 that absorbs fluctuations in ink pressure is formed substantially corresponding to the shape of the reservoir 66. The supply of the ink to the reservoir 66 is performed via an ink supply tube 75, which penetrates the flow path sealing plate 63 and communicates with the reservoir 66. The ink supply tube 75 is connected to a central position of the elongated reservoir 66, which shortens a flow path for the ink supplied from the ink supply tube 75 into the reservoir 66 to reach the end of the reservoir 66. This is to minimize the flow path resistance.

As shown in FIG. 4, the liquid ejecting apparatus according to the present embodiment includes a cleaning mechanism 30. The cleaning mechanism 30 includes a cap member 31 that is pressed against the nozzle forming surface of the recording head 20 to form a sealed space between the recording head 20 and the nozzle forming surface when cleaning the recording head 20, and reduces the pressure of the sealed space to a negative pressure. Suction pump 32
And an additive supply means 33 for supplying an additive for assisting cleaning to the closed space and mixing the additive with the liquid discharged from the plurality of nozzle openings 65 into the closed space.

The additive supply means 33 includes a cap member 31
Has an additive flow path 34 that penetrates through the side wall and opens at one end into the closed space. A flow control valve 35 is provided in the middle of the additive flow path 34, and the opening of the flow control valve 35 is adjusted by the control unit 36, thereby controlling the flow rate of the additive discharged into the closed space. be able to. The additive is discharged into the closed space from the end opening of the additive flow path 34 by applying a negative pressure to the closed space formed between the cap member 31 and the nozzle forming surface.

The additive is in a liquid form, and the cap member 31
It has at least one of a defoaming effect on the ink discharged into the nozzle and a re-dissolving effect on the ink fixed in the nozzle opening 65. The additive is preferably
Surfynol TG: 0.3% / triethylene glycol monobutyl ether: 5% / triethanolamine:
0.7% / remaining amount: has the composition of water.

Next, the head cleaning method in the liquid ejecting apparatus according to the present embodiment will be explained with reference to FIGS.

First, when the cleaning process is started,
As shown in step 11, any operation unnecessary for the cleaning process such as the paper feeding operation is prohibited, and in this state, the wiping member 11 (see FIG. 1) advances on the movement locus of the recording head 20.

Next, the carriage 1 is moved to the non-printing area, and the nozzle forming surface of the recording head 20 is moved to the wiping member 1.
1 (step 12). Thus, dust, paper dust, and the like attached to the nozzle forming surface of the recording head 20 are removed.

Subsequently, the carriage 1 is moved to the capping position, and a large amount of ink is sucked from the recording head 20 (step 13). FIG. 6 shows the state at this time. FIG. 6A shows a state in which the nozzle forming surface of the recording head 20 is sealed with a cap member 31. Subsequently, as shown in FIG. A negative pressure is accumulated in 31.

Due to the negative pressure in the cap member 31, ink is sucked and discharged into the cap member 31 as shown in FIG. At the same time as the suction and discharge of the ink, the additive for assisting the cleaning is sucked and released into the cap member 31 through the additive flow path 34 and mixed with the ink discharged into the cap member 31. Then, as shown in FIG. 6D, an amount of ink and additive corresponding to the negative pressure in the cap member 31 is discharged. Since the additive has a defoaming effect on the liquid ink and a re-dissolving effect on the solidified ink, foaming of the ink discharged into the cap member 31 is suppressed, and the additive adheres to the nozzle opening 65. Removal of waste ink is promoted.

Next, as shown as step 14 in FIG. 5, a step of a negative pressure release standby process is executed. In this step, the state where the nozzle forming surface of the recording head 20 is sealed by the cap member 31 is maintained, and the process waits until a predetermined time required for the internal space of the cap member 31 to return to the atmospheric pressure elapses. The predetermined time is set to, for example, about 3 seconds, and a predetermined amount of ink is discharged from the recording head 20 as the time elapses, and the negative pressure in the internal space of the cap member 31 becomes substantially equal to the atmospheric pressure.

When the pressure in the cap member 31 reaches the atmospheric pressure in this manner, the sealing of the nozzle forming surface of the recording head 20 by the cap member 31 shown in step 15 in FIG. , The operation of discharging ink from the cap member 31 is performed. The ink discharged from the cap member 31 is discharged to the waste liquid tank 40.

Subsequently, the wiping operation shown as step 16 in FIG. 5 is executed. That is, the nozzle forming surface of the recording head 20 is wiped by the wiping member 11 by the movement of the carriage 1 in the printing area direction, and the ink attached to the nozzle forming surface of the recording head 20 is wiped by the wiping member 11.

Next, at step 17, the suction pump 3
2 is driven again, and the ink retained in the cap member 31 at the time of ink suction in step 15 is sucked and discharged to the waste liquid tank 40.

Next, at step 18, the recording head 2
0 is moved to the capping position, and the nozzle forming surface of the recording head 20 is sealed by the cap member 31. Subsequently, operations other than the prohibited cleaning process are enabled (step 19), and a standby state is set in a state where the flushing operation for cleaning is executed (step 20), and the cleaning operation is completed.

As described above, according to the present embodiment, when cleaning the recording head 20, the additive having the defoaming effect on the liquid ink and the re-dissolving effect on the solidified ink is applied to the cap member 31. Since the ink is supplied to the inside, the bubbling of the ink discharged into the cap member 31 is suppressed, the removal of the ink fixed in the nozzle opening 65 is promoted, and the cleaning of the recording head 20 is performed with high reliability. Can be implemented below.

Further, since the additive housed separately from the ink supplied to the recording head 20 is mixed into the ink for the first time at the time of cleaning, there is a case where the additive is previously added to the ink. Differently, the type and amount of additive can be freely selected.

[0049]

As described above, according to the present invention, when cleaning the head portion, an additive for assisting cleaning is supplied to the inside of the cap member and discharged to the inside of the cap member. Since the liquid is mixed with the liquid, cleaning of the head portion can be performed with high reliability.

Further, since the additive housed separately from the liquid supplied to the head portion is mixed into the liquid for the first time at the time of cleaning, unlike the case where the additive is added to the liquid in advance. The type and amount of the additive can be freely selected.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a liquid ejecting apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a recording head including a piezoelectric vibrator in a longitudinal vibration mode in a liquid ejecting apparatus according to an embodiment of the present invention.

FIG. 3 is a transverse sectional view taken along line AA of FIG. 2;

FIG. 4 is a diagram showing a schematic configuration of a recording head, an ink cartridge, and a cleaning mechanism in the liquid ejecting apparatus according to the embodiment of the present invention.

FIG. 5 is a view showing a sequence of a head cleaning method in the liquid ejecting apparatus according to the embodiment of the present invention.

FIG. 6 is a schematic diagram for explaining a head cleaning operation performed according to the sequence shown in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carriage 7 Ink cartridge 20 Recording head (head part) 30 Cleaning mechanism 31 Cap member 32 Suction pump 33 Additive supply means 34 Additive flow path 35 Flow control valve 36 Control part 37 Piezoelectric vibrator 62 Case member 65 Nozzle opening 73 Vibration Board

Claims (10)

[Claims] A head unit having a plurality of nozzle openings from which liquid droplets are ejected; a liquid storage unit configured to store liquid supplied to the head unit and reciprocate integrally with the head unit;
A cleaning mechanism for cleaning the head unit, wherein the cleaning mechanism is pressed against a nozzle forming surface of the head unit when cleaning the head unit, and a closed space is formed between the head unit and the nozzle forming surface. Forming a cap, a suction pump for making the closed space a negative pressure, and supplying an additive for assisting cleaning to the closed space to supply the liquid discharged from the plurality of nozzle openings to the closed space. A liquid supply device, comprising: an additive supply means for mixing the additive; and wherein the additive supply means has an additive flow path penetrating the cap member and having one end opened to the closed space. 2. An additive supply means, comprising: a flow control valve provided in the middle of the additive flow path; and a flow rate of the additive discharged into the closed space by adjusting an opening degree of the flow control valve. The liquid ejecting apparatus according to claim 1, further comprising: a control unit configured to control the liquid ejecting apparatus. 3. The method according to claim 1, wherein the additive is discharged into the closed space from an end opening of the additive flow path by applying a negative pressure to the closed space. Liquid ejection device. 4. The method according to claim 1, wherein the additive has at least one of a defoaming effect on the liquid discharged into the closed space and a re-dissolving effect on the liquid fixed in the nozzle opening. The liquid ejecting apparatus according to claim 1. 5. The liquid ejecting apparatus according to claim 1, wherein the liquid ejected from the plurality of nozzle openings is ink. 6. A head unit having a plurality of nozzle openings from which droplets are ejected, a liquid storage unit that stores liquid supplied to the head unit, and reciprocates integrally with the head unit.
A head cleaning method in a liquid ejecting apparatus comprising: a step of pressing a cap member against a nozzle forming surface of the head portion to form a closed space between the nozzle forming surface and the cap member; A step of applying a negative pressure, and an additive for assisting cleaning is supplied to the closed space via an additive flow path that penetrates through the cap member and one end of which opens into the closed space. Mixing the liquid discharged from the nozzle opening into the closed space with the liquid discharged from the nozzle opening. 7. The method according to claim 6, wherein the flow rate of the additive discharged into the closed space is controlled by adjusting the opening of a flow control valve provided in the middle of the additive flow path. A head cleaning method for a liquid ejecting apparatus. 8. The method according to claim 6, wherein the additive is discharged into the closed space from an end opening of the additive flow path by applying a negative pressure to the closed space. A head cleaning method for a liquid ejecting apparatus. 9. The method according to claim 9, wherein the additive has at least one of a defoaming effect on the liquid discharged into the closed space and a re-dissolving effect on the liquid fixed in the nozzle opening. Item 9. A head cleaning method in the liquid ejecting apparatus according to any one of Items 6 to 8. 10. The head cleaning method for a liquid ejecting apparatus according to claim 6, wherein the liquid ejected from the plurality of nozzle openings is ink.