JP2003165230A - Ink-jet recording head and its recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent adhesion of paper dust, dust or the like to the periphery of a nozzle part of an ink jet recording head, to prevent drying or the like of ink in the periphery of the nozzle part and further to improve the cleanability of the periphery of the nozzle part in relation to the ink jet recording head and its recorder for recording to recording papers with the use of an ink jet head. <P>SOLUTION: An air duct set to surround a nozzle plate with a plurality of nozzles is made movable to the nozzle plate. The air duct is projected from a nozzle formation face of the nozzle plate at a recording time and at a recording standby time to jet humidification air. The air duct is retreated towards the nozzle plate at a maintenance operation for the recording head to jet humidification air. Moreover, a cap member for capping nozzles is set to the air duct. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording head for ejecting inkjet ink onto a conveyed recording sheet for recording and an apparatus therefor, and in particular, paper powder, dust or the like around the nozzle portion of the recording head. Prevention of adhesion of
And to prevent ink from drying around the nozzle.

[0002]

2. Description of the Related Art In the case of an apparatus for performing ink jet recording on a recording sheet, adhesion of paper powder or dust around the nozzle portion of a recording head or thickening of ink around the nozzle portion is a cause.
It is important to eliminate printing defects due to ink curling and ejection failure.

Up to now, recording papers with a reduced amount of paper dust and inks which are difficult to dry have been developed, but they are not sufficient in terms of performance. Therefore, it is necessary to take countermeasures on the ink jet recording head and the apparatus side thereof, and many proposals have been made to prevent the adhesion of paper powder, dust and the like to the periphery of the nozzle portion of the recording head and the ink drying of the nozzle portion.

For example, in the case of a continuous ink jet recording head in which ink particles continuously discharged from a nozzle are charged to collect ink particles unnecessary for recording, ink is ejected while ejecting air from an air duct provided at the tip of the nozzle. Since paper is ejected, the amount of paper powder, dust, etc. attached to the periphery of the nozzle is extremely small. Further, since the ink is ejected and collected in the air duct, the inside of the air duct can be kept at high humidity and the ink around the nozzle portion can be prevented from drying.

However, nothing is disclosed about the cleaning property of thickened ink, dust and the like adhering to the periphery of the nozzle portion covered with the air duct, that is, the workability at the time of so-called maintenance of the recording head.

On the other hand, as a correspondence on the device side, Japanese Patent Laid-Open No.
As described in Japanese Patent No. 1-035186, a paper dust suction tube communicating with a suction fan is arranged near the recording head, or as described in Japanese Patent No. 2796719, cleaning in which an adhesive layer is formed. It has been proposed to remove paper dust attached to the paper feed roller with a tool.

[0007]

Due to the adhesion of paper powder or dust around the nozzle portion of the recording head, or the ink deflection or non-ejection caused by the thickening of the ink around the nozzle portion,
This will cause printing defects. Recording paper that reduces the amount of paper dust generated and ink that does not dry easily have been developed, but it is not sufficient in terms of performance.

On the apparatus side, it is possible to dispose a paper dust suction tube communicating with a suction fan near the recording head, or to remove the paper dust adhering to the paper feed roller with a cleaning tool having an adhesive layer. However, there is a limit in the performance of removing paper powder and dust.

Further, in order to prevent paper dust or dust from adhering to the periphery of the nozzle portion on the recording head side, in the case of a continuous ink jet recording head, ink is ejected while ejecting air from an air duct provided at the tip of the nozzle. Although it is discharged, there is a big problem in cleanability around the nozzle part in a narrow area covered by the air duct.

The object of the present invention is to reduce the adhesion of paper powder, dust and the like to the periphery of the nozzle portion, prevent the ink from drying around the nozzle portion, and increase the viscosity of the ink adhered to the periphery of the nozzle portion. It is an object of the present invention to provide an ink jet type recording head and a recording apparatus therefor which are excellent in cleaning properties such as ink, paper powder, and dust.

[0011]

In order to achieve the above object, in the present invention, a nozzle plate having a plurality of nozzles arranged in a row at a constant pitch, and a nozzle plate provided so as to surround the nozzles of the nozzle plate. In an ink jet recording head, which comprises an air duct and an air ejecting means communicating with the air duct, and ejects ink from the nozzle while sending air from the air duct to the nozzle, the nozzle plate is attached to the air duct. Movable means that can move relative to each other is provided. In this case, at the time of inkjet recording and recording standby, the air duct is projected from the nozzle forming surface of the nozzle plate to eject air, so that not only adhesion of paper powder and dust around the nozzle part can be prevented, but also head maintenance is possible. Since the air duct sometimes recedes toward the nozzle plate side, the cleanability of the nozzle plate surface can be improved.

Further, since the movable means of the air duct is provided in association with the recording head or the movable means of the air duct is provided in conjunction with the retract operation of the recording head, the movement of the air duct can be easily performed.

Alternatively, since the cap member for capping the nozzle forming surface of the nozzle plate by moving the air duct is provided in the air duct,
It is possible to prevent the ink around the nozzle portion from drying.

Further, the air velocity and the air volume ejected from the air duct are reduced during the ink jet recording and the recording standby, and the air velocity and the air volume are increased during the maintenance operation of the recording head. Therefore, the ink ejected during the recording is ejected. It is possible to prevent flying bending and prevent ink from entering the air duct during the maintenance operation.

Alternatively, at the time of recording, humidified air is jetted from the air duct and a moisturizing material is provided on the inner wall of the air duct, so that the ink around the nozzle portion can be prevented from drying.

Further, since the air duct is made of an ink repellent material or the surface of the air duct is treated to be ink repellent, ink does not adhere to the air duct.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An example of the present invention will be described below with reference to the drawings. FIG. 1 is a partial cross-sectional view showing an ink jet recording head as an example of the present invention.

First, referring to FIG. 1, 1 is a nozzle plate, 1a is a nozzle formed on the nozzle forming surface 1b of the nozzle plate 1 in a row at a constant pitch, 2 is an ink chamber, and 3 is a filling chamber. Ink, 4 is an air duct made of an ink repellent material provided so as to surround the nozzle 1a of the nozzle plate 1, 4a is an air ejection hole provided so as to face the position of the nozzle 1a, and 5 is provided on the inner wall of the air duct 4. A moisturizing material made of continuous foam sponge, 6 is a blower which communicates with the air duct 4 and sends clean air 7 in which dust and the like are filtered in advance, 8 is a humidifier for humidifying the air 7 sent from the blower 6, and 9 is air Solenoid 10, which is a movable means capable of projecting and retracting the nozzle plate 1 of the duct 4, is a recording sheet.

Next, the operation of the recording head at the time of printing will be described with reference to FIG. 1. The filling ink 3 in the ink chamber 2 is
The pressure change of the ink chamber 2 due to the displacement of the vibrating plate to which the piezoelectric element (not shown) is bonded causes the ink droplets 3a from the nozzles 1a to land on the recording paper 10 moving at a constant speed. Since the piezoelectric element is driven only when recording is required, it is called a drop-on-demand inkjet recording head, as opposed to the continuous inkjet recording head described above.

The filling ink 3 in the ink chamber 2 is supplied from an ink tank (not shown). Further, the stop position of the air duct 4 with respect to the nozzle plate 1 is held by the solenoid 9 so that the air ejection hole 4a is projected to the nozzle forming surface 1b. On the other hand, the air 7 indicated by a plurality of arrows is sent out from the blower 6 and then humidified by the humidifier 8 so that the nozzle 1a
The recording sheet 10 is jetted from the air jet holes 4a through the air flow paths 4b on both sides of the sheet. At this time, the wind speed and the air volume of the air 7 ejected from the air ejection hole 4a depend on the ink droplets 3
It is set to be small enough not to cause a problem such as a bend in the ink flight of a.

Therefore, the ink droplet 3a ejected from the nozzle 1a is accompanied by the humidified air 7 and the air ejection hole 4
Since it passes through a, it is possible to prevent paper dust, dust, and the like carried by the moving recording paper 10 from entering the peripheral portion of the nozzle 1a.

Further, since the position of the air duct 4 and the jetting state of the air 7 are the same as in printing even during printing standby, it is possible to prevent paper powder, dust, etc. from entering the peripheral portion of the nozzle 1a and to prevent nozzle 1a. It is possible to prevent the surrounding ink from drying.

Further, since the air duct 4 protrudes from the nozzle plate 1, even if the recording paper 10 is jammed at the nozzle plate 1, the recording paper 10 comes into contact with the nozzle plate 1 so that the nozzles 1a are exposed. Adhesion of paper powder, dust, etc. can be avoided. In addition, since the moisturizing material 5 is provided on the inner wall of the air duct 4, the humidified state inside the air duct 4 is stabilized, and it is possible to prevent the periphery of the nozzle 1a from drying even when the temperature of the recording paper is high.

Next, the operation when the recording head is maintained will be described. FIG. 2 is a partial cross-sectional view for explaining the recording head maintenance operation state of the ink jet recording head as an example of the present invention.

Air duct 4 for nozzle plate 1
The position 9 is held by the solenoid 9 so that the air ejection hole 4a retreats toward the nozzle forming surface 1b and the air ejection hole 4a is slightly left from the nozzle plate 1. On the other hand, 11 is a recording head maintenance portion having an air suction hole 11a facing the position of the air ejection hole 4a, and has a function of sucking air from the air suction hole 11a by having a suction means (not shown). Further, when the recording head maintenance operation is performed, the air suction hole 11a of the recording head maintenance unit 11 is moved by the moving means (not shown) to the air duct 4
The air 7 sent from the blower 6 can flow into the air suction hole 11a from the air ejection hole 4a because the air 7 comes into contact with the air suction hole 11a.

Here, since the ink droplet 3a is ejected from the nozzle 1a at the same time when the air 7 flows into the recording head maintenance section 11, unnecessary ink whose viscosity has increased due to contact with the outside air at the tip of the nozzle 1a, The paper powder and dust around the nozzle 1a can be discharged together with the recording head maintenance unit 11.

When the ink droplet 3a is ejected from the nozzle 1a with the air ejection hole 4a protruding from the nozzle plate 1 as shown in FIG. 1, the ink droplet 3a overflows around the air ejection hole 4a. It goes without saying that it cannot be smoothly discharged to the maintenance unit 11. In particular, in the case of a drop-on-demand type ink jet recording head, ink droplets tend to adhere to the periphery of the nozzle portion during ink ejection during maintenance of the recording head, so that the ink droplet overflow becomes noticeable.

Therefore, when the recording apparatus is powered on or in recording standby, the air suction hole 1 of the recording head maintenance unit 11 removes thickening ink, paper powder, dust, etc. adhering to the periphery of the nozzle unit.
It can be sucked into 1a.

Further, since the air 7 blown out from the blower 6 and jetted from the air jet holes 4a has a large wind speed and volume, paper dust, dust, ink, etc. adhering to the periphery of the nozzle portion should enter the air duct 4. The cleaning performance of the nozzle plate can be improved. This is particularly effective in the case of a drop-on-demand type ink jet recording head that ejects a small amount of energy.

Next, the capping operation around the nozzle portion when the power is off, which is another function for maintaining the recording head, will be described with reference to FIGS. 3 and 4.

FIG. 3 is a partial cross-sectional view for explaining the operation of the recording head cap mechanism of the ink jet recording head which is an example of the present invention.

In FIG. 3, the cap 12 fixed to the inner wall of the air duct 4 is held by the solenoid 9 so that the cap 12 is pressed against the nozzle 1a. In this state, it is possible not only to prevent paper powder and dust from adhering to the nozzle 1a, but also to prevent ink drying of the nozzle 1a portion. The material of the cap 12 is preferably rubber which has elasticity and is not attacked by ink.

FIG. 4A is a view of the nozzle plate 1 and the air duct 4 in FIG. 3 seen from the direction A. The nozzles 1a are arranged on the nozzle plate 1 in a row at a constant pitch.
The cap 12 fixed to the inner wall of the air duct 4.
Are aligned respectively. Further, air ejection holes 4a facing the nozzle 1a are provided between the caps 12, respectively.

FIG. 4 (b) shows the position of the air duct 4 relative to the nozzle plate 1 in FIG. 4 (a), which is shifted in the B direction, which is the direction in which the nozzles are arranged, by a moving means (not shown). Here, the nozzle 1a and the air ejection hole 4
“A” is aligned with each other, and indicates the state at the time of inkjet recording shown in FIG. 1 or at the time of recording standby shown in FIG. In this state, since the nozzle 1a and the cap 12 are separated from each other, there is no adverse effect on ink ejection or the like.

In this example, the movable means of the air duct with respect to the nozzle plate is provided on the recording head side, but this movable means may be interlocked with the retract mechanism of the recording head. The retract mechanism of the recording head performs an operation of moving the recording head away from the recording sheet when a jam or the like of the recording sheet occurs, and the recording head movable means is provided on the recording apparatus side. Since the moving direction of this recording head matches the moving direction of the air duct with respect to the nozzle plate in this example, for example, a protrusion is provided in a part of the air duct, and the head moving force on the recording apparatus side is provided through this protrusion. May be transmitted to the air duct.

[0036]

As described above, according to the present invention, during the ink jet recording and the recording standby, the air duct is projected from the nozzle forming surface of the nozzle plate to eject the air, so that the paper dust or the like around the nozzle portion is ejected. Not only can dust and the like be prevented from adhering, but since the air duct retracts toward the nozzle plate side during head maintenance, the cleanability of the nozzle plate surface can be improved.

Further, since the cap member for capping the nozzle forming surface of the nozzle plate by the movement of the air duct is provided in the air duct, it is possible to prevent the ink around the nozzle portion from drying.

Alternatively, since the humidified air is jetted from the air duct and the moisturizing material is provided on the inner wall of the air duct, it is possible to prevent the ink around the nozzle portion from drying.

Further, since the air velocity and the air volume ejected from the air duct are reduced during the ink jet recording and the recording standby, and the air velocity and the air volume are increased during the maintenance operation of the recording head, the ink ejected during the recording is ejected. It is possible to prevent flying bending and prevent ink from entering the air duct during the maintenance operation.

Since the air duct protrudes from the nozzle plate, the recording paper comes into contact with the nozzle plate when the recording paper is jammed, and paper dust, dust or the like is attached to the peripheral portion of the nozzle or a mechanical shock is given. There is no fear.

Further, since the moisturizing material 5 is provided on the inner wall of the air duct, the humidified state in the air duct is stabilized, and the periphery of the nozzle can be prevented from being dried even if the temperature of the recording paper is high.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an inkjet recording head as an example of the present invention.

FIG. 2 is a partial cross-sectional view for explaining a recording head maintenance operation state of an inkjet recording head that is an example of the present invention.

FIG. 3 is a partial cross-sectional view for explaining the operation of the recording head cap mechanism of the inkjet recording head that is an example of the present invention.

FIG. 4 is a schematic view of the nozzle plate 1 and the air duct 4 in FIG. 3 viewed from the direction A.

[Explanation of symbols]

1 is a nozzle plate, 1a is a nozzle, 1b is a nozzle forming surface, 2 is an ink chamber, 3 is filled ink, 3a is an ink droplet,
4 is an air duct, 4a is an air ejection hole, 4b is an air flow path, 5 is a moisturizing material, 6 is a blower, 7 is air, 8 is a humidifier, 9 is a renoid, 10 is a recording sheet, and 11 is a recording head maintenance section. , 11a are air suction holes, and 12 is a cap.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Takahagi             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. (72) Inventor Hajime Terachi             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. F-term (reference) 2C056 EA04 EA14 EA16 EA17 EC04                       EC08 EC30 EC53 EC57 HA13                       HA19 HA60 JA01 JC18 JC20

Claims (10)

[Claims] 1. A nozzle plate comprising a plurality of nozzles arranged in a row at a constant pitch, an air duct provided so as to surround the nozzles of the nozzle plate, and an air injection means communicating with the air duct. In an ink jet recording head that ejects ink from the nozzle while sending air from the air duct to the nozzle, the air duct is provided with a movable means that can move with respect to the nozzle plate. Inkjet recording head. 2. The ink jet recording head according to claim 1, wherein the moving means provided in the air duct has the same moving direction as the ink ejecting direction, and the moving means is provided in the recording head. 3. The ink jet recording head according to claim 1, wherein the movable means of the air duct is interlocked with a retract mechanism of the recording head. 4. The ink jet recording head according to claim 1, wherein the air duct is provided with a cap member that caps the nozzles by moving in the nozzle arrangement direction. 5. The ink is ejected by projecting the air duct from the nozzle forming surface of the nozzle plate during ink jet recording and recording standby, and retracting the air duct to the nozzle plate side during maintenance operation of the recording head. The ink jet recording head according to any one of claims 1 to 4, wherein air is jetted. 6. The air wind velocity and air volume ejected from the air duct during ink jet recording and recording standby are reduced, and the air wind velocity and air volume ejected from the air duct during the maintenance operation of the recording head are increased. The ink jet recording head according to claim 1. 7. The ink jet recording head according to claim 1, wherein humidified air is jetted from the air duct during ink jet recording. 8. The ink jet recording head according to claim 1, wherein a moisturizing material is provided on an inner wall of the air duct on the nozzle plate side. 9. The ink jet recording head according to claim 1, wherein the air duct is made of an ink repellent material, or the surface of the air duct is subjected to an ink repellent treatment. 10. A recording apparatus comprising the ink jet recording head according to claim 1.