JP2004338244A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the discharge stability of ink from lowering by protecting the nozzle face of an inkjet recording device. <P>SOLUTION: The nozzle face 9 can be protected from damage or the like due to contact or a collision with a recording medium by providing a protective member 10 on the nozzle face 9 of the inkjet recording device 1 having an inkjet head 2 discharging the ink as ink droplets from the discharge holes 3 of the nozzle face 9. Furthermore, by providing through holes 11 larger than the discharge holes 3 to the protective member 10, applying pressure to the ink so as to reserve the ink extruded from the discharge holes 3 in the through hole 11 and sucking the ink by a suction section 7, foreign matter is suspended in the ink reserved in the through holes 11 and is completely removed from the nozzle face 9 together with the ink even if the foreign matter sticks to the nozzle face 9 in the vicinity of the discharge holes 3, a lowering of the discharge stability of the ink can be prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inkjet recording device.
[0002]
[Prior art]
An ink jet recording apparatus is provided with an ink jet head having a nozzle surface provided with an ejection hole and ejecting ink as ink droplets from the ejection hole, and is an apparatus for recording an image on a recording medium by the inkjet head.
[0003]
In such an ink jet recording apparatus, since the ink jet head is close to the recording medium during the recording operation, the ink scatter generated by the collision of the ink droplets with the recording medium may contaminate the nozzle surface of the ink jet head. In particular, in the on-demand type ink jet recording apparatus, since the ejection energy of the nozzle droplet is small and the ink jet head is provided at an interval of about several mm with respect to the recording medium, ink adheres to the nozzle surface due to ink scattering. And the nozzle surface is contaminated. In addition, foreign substances such as dust and dust existing on the recording medium may adhere to the nozzle surface and its peripheral portion. In order to solve these problems, a cleaning technique has been proposed in which the nozzle surface is wiped (wiped) with a flexible flat wipe blade to remove ink remaining on the nozzle surface (Patent Document 1). reference).
[0004]
On the other hand, the recording medium in a state where wrinkles or floating have occurred may contact or collide with the nozzle surface, thereby damaging the nozzle surface or its peripheral portion. Therefore, a method has been proposed in which the nozzle surface of the head substrate is recessed by 5 μm to 500 μm from the surface of a mask plate (protective member) surrounding the head substrate in which the ejection holes are formed (see Patent Document 2). Further, a method has been proposed in which a nozzle protection plate (protection member) supported at a predetermined distance from the nozzle surface is provided, and ink is discharged along the nozzle protection plate (see Patent Document 3). With these techniques, the nozzle surface and its peripheral portion can be protected from contact or collision with the recording medium.
[0005]
[Patent Document 1]
JP-A-6-71904 [Patent Document 2]
Japanese Patent Application Laid-Open No. Hei 5-3300041 [Patent Document 3]
JP 2001-18390 A
[Problems to be solved by the invention]
However, in the technique of Patent Literature 2, the ink mist generated when the ink flies tends to accumulate in the depression. In addition, foreign substances such as dust and dirt enter the depression, and furthermore, the depression makes it difficult to perform cleaning by wiping. If the ink or foreign matter accumulates in the depressions and grows as a lump as described above, the lump becomes a factor that causes clogging of the nozzle and bending of the flight. Therefore, there is a problem in that the ink or foreign matter accumulated in the depression becomes a cause of lowering the ejection stability of the ink.
[0007]
On the other hand, in the technique of Patent Document 3, if a certain amount of ink does not accumulate, the ink does not flow through the nozzle protection plate, but stays there due to surface tension, and is dried and fixed. Further, the foreign matter is harder to flow than the ink, so that the foreign matter stays on the spot, which causes the clogging of the nozzle and the bending of the flight. Therefore, there is a problem that the fixed ink and foreign matter cause a reduction in the ejection stability of the ink.
[0008]
An object of the present invention is to provide an ink jet recording apparatus capable of protecting a nozzle surface and preventing a decrease in ink ejection stability.
[0009]
[Means for Solving the Problems]
In the ink jet recording apparatus of the present invention, a protection member for covering and protecting the nozzle surface is provided on the nozzle surface of the ink jet head that discharges ink as ink droplets from the discharge hole provided on the nozzle surface, and faces the discharge hole. A through-hole larger than the ejection hole was provided in the protection member positioned at the position, and pressure was applied to the ink so that the ink extruded from the ejection hole was accumulated in the through-hole, and the ink accumulated in the through-hole was sucked.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a front view schematically showing an inkjet recording apparatus 1 of the present embodiment, FIG. 2 is an external perspective view schematically showing the vicinity of an inkjet head 2 provided in the inkjet recording apparatus 1, and FIG. FIG. 4 is a sectional view taken along line AA of FIG.
[0011]
The ink jet recording apparatus 1 includes an ink jet head 2 that discharges ink as ink droplets from a discharge hole 3 onto a recording medium, an ink tank 5 that is connected to the ink jet head 2 via an ink supply path 4 and stores ink, and an ink jet head. A pressurizing unit 6 for applying pressure to the ink so as to push out the ink from the second ejection holes 3; and a suction unit 7 for sucking the ink pushed out from the ejection holes 3 by the pressurizing unit 6. Further, the inkjet recording apparatus 1 is equipped with a recording medium transport unit (not shown) for sequentially sending out a recording medium such as paper and transporting the recording medium in the sub-scanning direction, and reciprocates in the main scanning direction with the inkjet head 2 mounted thereon. A carriage (not shown) is also provided.
[0012]
The ink jet head 2 includes a plurality of nozzles 8 formed in a substantially straight line. Thus, the ejection holes 3 of the plurality of nozzles 8 are formed on the nozzle surface 9 of the inkjet head 2 in a substantially straight line. That is, the inkjet head 2 is configured to eject ink as ink droplets from the ejection holes 3 of the nozzle surface 9. As the ink jet head 2, for example, a piezoelectric ink jet head 2 using a piezoelectric element (for example, a piezo element), a thermal ink jet head 2 using a heating element, or the like is used.
[0013]
The nozzle surface 9 is provided with a protection member 10 that covers and protects the nozzle surface 9. As the protective member 10, a protective sheet or the like is used, but the present invention is not limited to this. For example, a plate-like protective member or a protective film applied on the nozzle surface may be used. The protective member 10 is provided with a plurality of through holes 11 larger than the discharge holes 3 positioned at positions facing the discharge holes 3. The through hole 11 is formed in a circular shape, but is not limited to this, and may be formed in, for example, an elliptical shape.
[0014]
The pressurizing unit 6 includes a pressurizing pump 12 for generating a pressurizing force for extruding the ink existing in the nozzle 8 in the ejection direction, and a pressurizing path 13 for communicating the pressurizing pump 12 with the ink tank 5. ing. The pressurizing unit 6 uses a pressurizing pump 12 to extrude the ink from the ejection holes 3 of the inkjet head 2 in the ejection direction, and applies pressure to the ink so that the extruded ink is stored in the through holes 11.
[0015]
The suction unit 7 is located at a position facing the nozzle surface 9 and is provided so as to be movable in a direction in which the plurality of nozzles 8, that is, the ejection holes 3 are arranged. , A suction pump 16 for generating a suction force for sucking ink stored in the through hole 11 and ink remaining on the protection member 10, and a communication between the suction head 14 and the suction pump 16. It comprises a suction path 17 and a waste ink tank 18 connected to the suction pump 16 and containing waste ink. The movement drive unit 15 includes a guide screw 19 that guides and moves the suction head 14 in a direction in which the plurality of discharge holes 3 (nozzles 8) are arranged, and a drive motor 20 that drives the guide screw 19 to rotate. I have. The suction unit 7 moves the suction head 14 in the direction in which the ejection holes 3 are lined up by the movement driving unit 15, and the ink stored in the through holes 11 and the ink remaining on the protection member 10 by the suction force of the suction pump 16. Is sucked from a position facing the nozzle surface 9. The sucked ink (waste ink) flows into the waste ink tank 18 through the suction path 17.
[0016]
Here, as the ink, various inks such as a water-based ink, an oil-based ink, a solvent ink, and a UV ink (ultraviolet curable ink) are used. The UV ink includes, for example, a pigment, a monomer, an oligomer, a photopolymerization initiator, a dispersant, and other additives (for example, a surface tension adjuster).
[0017]
Further, in the present embodiment, in order to store the ink pushed out in the discharge direction from the discharge hole 3 in the through hole 11, the ink viscosity, the wettability of the surface of the protection member 10, the thickness of the protection member 10, and the penetration The pressing force by the pressing unit 6 is adjusted in consideration of the size, shape, and the like of the hole 11. In addition, if necessary, the ink used (for adjusting the ink viscosity), the material of the protective member 10 (for adjusting the wettability of the surface of the protective member 10), the thickness of the protective member 10, and the through hole The size, shape, etc. of 11 are also adjusted.
[0018]
FIG. 5 is a block diagram schematically showing the electrical connection of each unit included in the inkjet recording apparatus 1. The inkjet recording apparatus 1 incorporates a controller 30. The controller 30 includes a CPU (Central Processing Unit) 31, which centrally controls each unit, a ROM (Read Only Memory) 32, which stores various programs executed by the CPU 31, and the CPU 31. A random access memory (RAM) 33, which functions as a work area, and a timer 34 are connected by a bus line 35.
[0019]
The inkjet head 2 is connected to the CPU 31 via an inkjet head control unit 36, the drive motor 20 is connected via a drive motor control unit 37, and the pressure pump 12 and the pressure pump 12 are connected via a pump control unit 38. A suction pump 16 is connected. Further, an external device (not shown) such as a personal computer is connected to the CPU 31 via a communication interface (not shown), and further, a recording medium is conveyed via a drive control unit (not shown). Section (not shown) and a carriage (not shown) are connected.
[0020]
Such an ink jet recording apparatus 1 moves a carriage on which an ink jet head 2 is mounted while conveying a recording medium in a sub-scanning direction by a recording medium conveying unit based on image data received from an external device via a communication interface. An image is recorded (formed) on a recording medium by moving the inkjet head 2 from the home position (standby position) in the main scanning direction and controlling the driving of the inkjet head 2.
[0021]
Next, a cleaning operation in which the inkjet recording apparatus 1 cleans the nozzle surface 9 of the inkjet head 2 by the pressurizing unit 6 and the suction unit 7 will be described with reference to FIG. The cleaning operation is performed, for example, when the inkjet head 2 is located at the home position.
[0022]
6A and 6B schematically show, in an enlarged manner, the vicinity of the nozzle surface 9 of the ink jet head 2, wherein FIG. 6A is a cross-sectional view taken along the line AA before cleaning, and FIG. FIG. 3C is a cross-sectional view taken along line AA after cleaning.
[0023]
As shown in FIG. 6A, for example, a foreign substance F such as an ink droplet or dust adheres to the nozzle surface 9 near the ejection hole 3. In such a state, the ink jet recording apparatus 1 moves the ink jet head 2 to the home position, and controls the driving of the pressurizing unit 6 when the ink jet head 2 does not perform the recording operation. That is, the inkjet recording apparatus 1 drives and controls the pressure pump 12 to push out the ink from the ejection holes 3 in the ejection direction, and accumulates the ejected ink in the through holes 11. At this time, as shown in FIG. 6B, the ink remains in the through hole 11 due to surface tension, and the foreign matter F is floating in the ink. In such a state, the inkjet recording apparatus 1 then controls the driving of the suction unit 7. That is, the inkjet recording apparatus 1 drives and controls the drive motor 20 while driving and controlling the suction pump 16 to rotate the guide screw 19 and move the suction head 14 of the suction unit 7. Thereby, as shown in FIG. 6C, the ink stored in the through-hole 11 is sucked and removed by the suction unit 7. At this time, the foreign matter F is also sucked and removed together with the ink.
[0024]
As described above, in the present embodiment, even if the foreign matter F adheres to the nozzle surface 9 near the ejection hole 3, the ink is accumulated in the through hole 11 by the pressurizing unit 6 and then sucked by the suction unit 7. Since the foreign matter F floats in the ink stored in the through hole 11 and is completely removed from the nozzle surface 9 together with the ink, it is possible to prevent a decrease in the ejection stability of the ink. As a result, it is possible to prevent the occurrence of printing defects. Further, by providing the protection member 10 on the nozzle surface 9, the nozzle surface 9 can be protected from damage due to contact or collision of the recording medium.
[0025]
A second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a plan view schematically showing the inkjet head of the present embodiment, and FIG. 8 is a cross-sectional view of the inkjet head taken along line BB. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.
[0026]
The basic configuration of this embodiment is the same as that of the first embodiment. Here, differences between the present embodiment and the first embodiment will be described. On the nozzle surface 9 of the inkjet head 2, a plurality of discharge holes 3 are formed on three parallel straight lines extending in the longitudinal direction. In addition, a protection member 10 that covers and protects the nozzle surface 9 is provided on the nozzle surface 9. As the protective member 10, a protective sheet or the like is used. However, the present invention is not limited to this. For example, a plate-like protective member 10 or a protective film applied on the nozzle surface may be used.
[0027]
The protective member 10 is provided with a plurality of through holes 11 corresponding to two or more discharge holes 3. Here, one through hole 11 is associated with three discharge holes 3. That is, one through hole 11 is formed to have a size including three ejection holes 3, and the three ejection holes 3 exist in one through hole 11. The through hole 11 is formed in a substantially elliptical shape, but is not limited to this, and may be formed in a rectangular shape, for example. In addition, here, one through hole 11 is provided in association with three ejection holes 3, but is not limited thereto, and, for example, one through hole 11 is associated with two ejection holes 3. May be provided. In this case, one through hole 11 is formed to have a size including two discharge holes 3.
[0028]
Next, a cleaning operation in which the inkjet recording apparatus 1 cleans the nozzle surface 9 of the inkjet head 2 by the pressurizing unit 6 and the suction unit 7 will be described with reference to FIG. The cleaning operation is performed, for example, when the inkjet head 2 is located at the home position.
[0029]
9A and 9B schematically show, in an enlarged manner, the vicinity of the nozzle surface 9 of the inkjet head 2, wherein FIG. 9A is a sectional view taken along the line BB before cleaning, and FIG. FIG. 3C is a sectional view taken along line BB after cleaning.
[0030]
As shown in FIG. 9A, for example, foreign matter F such as ink droplets and dust adheres to the nozzle surface 9 near the ejection hole 3. In such a state, the ink jet recording apparatus 1 moves the ink jet head 2 to the home position, and controls the driving of the pressurizing unit 6 when the ink jet head 2 does not perform the recording operation. That is, the inkjet recording apparatus 1 drives and controls the pressure pump 12 to push out the ink from the ejection holes 3 in the ejection direction, and accumulates the ejected ink in the through holes 11. At this time, as shown in FIG. 9B, the ink remains in the through hole 11 due to the surface tension, and the foreign matter F is floating in the ink. In such a state, the inkjet recording apparatus 1 then controls the driving of the suction unit 7. That is, the inkjet recording apparatus 1 drives and controls the drive motor 20 while driving and controlling the suction pump 16 to rotate the guide screw 19 and move the suction head 14 of the suction unit 7. Thus, as shown in FIG. 9C, the ink stored in the through-hole 11 is sucked by the suction unit 7 and removed. At this time, the foreign matter F is also sucked and removed together with the ink.
[0031]
As described above, in the present embodiment, even if the foreign matter F adheres to the nozzle surface 9 near the ejection hole 3, the ink is accumulated in the through hole 11 by the pressurizing unit 6 and then sucked by the suction unit 7. Since the foreign matter F floats in the ink stored in the through hole 11 and is completely removed from the nozzle surface 9 together with the ink, it is possible to prevent a decrease in the ejection stability of the ink. As a result, it is possible to prevent the occurrence of printing defects. Further, by providing the protection member 10 on the nozzle surface 9, the nozzle surface 9 can be protected from damage due to contact or collision of the recording medium.
[0032]
In the present embodiment, a plurality of ejection holes 3 are provided, and a plurality of through holes 11 are provided in association with two or more ejection holes 3. Compared with the case where one through hole 11 is formed correspondingly, the through hole 11 can be easily formed in the protection member 10 and the processing of the protection member 10 becomes easy.
[0033]
In each embodiment, a plurality of ejection holes 3 are provided, and the suction unit 7 relatively positions the suction head 14 that covers a part of the plurality of ejection holes 3 and the inkjet head 2 and the suction head 14. And a movement drive unit 15 for moving the entirety of the plurality of discharge holes 3, the discharge holes 3 can be partially sucked, and a large suction pump is not required. Can be realized.
[0034]
In each embodiment, the suction unit 7 is configured such that the suction head 14 moves in the direction in which the plurality of ejection holes 3 are arranged. However, the present invention is not limited to this. It suffices if the structure 14 is configured to move over the entirety of the plurality of ejection holes 3.
[0035]
Further, in each embodiment, the suction head 14 is moved with respect to the inkjet head 2 by the movement driving unit 15, but the present invention is not limited to this, and the suction head 14 and the inkjet head 2 move relatively. For example, the inkjet head 2 may be configured to move with respect to the suction head 14.
[0036]
Further, in each of the embodiments, the suction head 14 is configured to cover a part of the plurality of discharge holes 3 in the inkjet head 2. However, the present invention is not limited to this. It may be configured to cover the hole 3. In this case, there is no need to provide the movement drive unit 15, and space saving and cost reduction can be realized.
[0037]
【The invention's effect】
According to the present invention, by providing a protective member on the nozzle surface, the nozzle surface can be protected from damage due to contact or collision of the recording medium, and even if foreign matter adheres to the nozzle surface near the ejection hole, Foreign matter floats in the ink stored in the through-hole and is completely removed from the nozzle surface together with the ink. Can be prevented from lowering.
[Brief description of the drawings]
FIG. 1 is a front view schematically showing an ink jet recording apparatus according to a first embodiment of the present invention.
FIG. 2 is an external perspective view schematically showing the vicinity of an inkjet head provided in the inkjet recording apparatus.
FIG. 3 is a plan view schematically showing an inkjet head.
FIG. 4 is a sectional view taken along line AA of the inkjet head.
FIG. 5 is a block diagram schematically showing an electrical connection of each unit included in the inkjet recording apparatus.
6A and 6B schematically show an enlarged view of the vicinity of the nozzle surface of the inkjet head, wherein FIG. 6A is a cross-sectional view taken along the line AA before cleaning, and FIG. FIG. 3C is a sectional view taken along line AA after cleaning.
FIG. 7 is a plan view schematically showing an inkjet head according to a second embodiment of the present invention.
FIG. 8 is a sectional view taken along line BB of the inkjet head.
9A and 9B schematically show, in an enlarged manner, the vicinity of the nozzle surface of the inkjet head, wherein FIG. 9A is a cross-sectional view taken along the line BB before cleaning, and FIG. FIG. 3C is a sectional view taken along line BB after cleaning.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ink jet recording apparatus 2 Ink jet head 3 Discharge hole 6 Pressurization part 7 Suction part 9 Nozzle surface 10 Protective member 11 Through hole 14 Suction head 15 Movement drive part

Claims (3)

An inkjet head having a nozzle surface provided with an ejection hole and ejecting ink as ink droplets from the ejection hole,
A protection member provided on the nozzle surface and covering and protecting the nozzle surface,
A through hole that is provided at the protection member and is located at a position facing the discharge hole, and is larger than the discharge hole;
A pressurizing unit that extrudes ink from the ejection holes in the ejection direction, and applies pressure to the ink so that the extruded ink is stored in the through holes;
A suction unit that suctions ink stored in the through hole from a position facing the nozzle surface,
An ink jet recording apparatus comprising: A plurality of the discharge holes are provided,
The ink jet recording apparatus according to claim 1, wherein a plurality of the through holes are provided in association with two or more of the ejection holes. A plurality of the discharge holes are provided,
The suction unit,
A suction head that covers a part of the plurality of discharge holes,
A movement drive unit that relatively moves the inkjet head and the suction head over the plurality of ejection holes,
The inkjet recording apparatus according to claim 1, further comprising:

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