JP3855434B2 - Inkjet recording device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording apparatus that records an image based on ejection of ink in a predetermined container from a nozzle provided in the container.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a printer using a piezoelectric element (PZT) for a print head of an ink jet printer is known. In such an ink jet head (print head of an ink jet printer), a pulse voltage corresponding to image data is applied to a piezoelectric element, and ink in an ink channel that becomes a predetermined container due to distortion of the piezoelectric element caused by the application of the pulse voltage. Is pressed, and an ink drop is ejected from a nozzle provided in the ink channel toward a recording sheet such as paper or an OHP sheet. On the recording sheet, an image based on image data transmitted from a personal computer or the like is printed by ejecting these ink drops.
[0003]
If the ink jet printer as described above is left unprinted for a long time, the exposed portion of the ink near the nozzle dries, the viscosity of the ink increases or the ink solidifies, causing the nozzle hole to become clogged, It adversely affects ink drop ejection. In general, in order to prevent the ink from drying near the nozzles, the ink jet printer has a nozzle surface (surface on which the nozzles of the ink jet head are formed) and a cap (a space that is in close contact with the nozzle surface and separated from the outside air). A cap mechanism is provided which is sealed by a member for forming the.
[0004]
[Problems to be solved by the invention]
However, the cap mechanism provided in the conventional ink jet printer as described above cannot completely prevent the ink from drying in the exposed portion near the nozzle, and cannot prevent clogging of the nozzle hole. .
[0005]
An object of the present invention is to provide an ink jet recording apparatus that can completely prevent clogging of nozzle holes.
[0006]
[Means for Solving the Problems]
An ink jet recording apparatus according to the present invention is an ink jet recording apparatus that records an image on a recording medium by ejecting ink in an ink channel from a nozzle provided in the ink channel onto the recording medium .
[0007]
The ink jet recording apparatus includes: an ink tank that stores ink; a common ink chamber that supplies ink to the ink channel; a first channel that supplies ink from the ink tank to the common ink chamber; and the common ink chamber. A second flow path for returning ink from the ink tank to the ink tank, and circulation means for circulating ink in a circulation path formed by the ink tank, the first flow path, the common ink chamber, and the second flow path And the circulating means draws the ink in the ink channel in the direction opposite to the ejection direction at the nozzle when the image is not recorded, thereby sucking the ink in the ink channel into the common ink chamber. The ink is circulated in the circulation path so as to be removed from the channel .
[0008]
According to the invention described in claim 1, when not performed recording of the image, the liquid surface of ink is formed inside the nozzles when recording images are moved toward the inside of the ink channels, the ink ink in the channel Ru removed from the aspirated ink channel to the common ink chamber. Thereby, when not in use, the ink does not dry near the nozzle hole, and the nozzle hole is completely prevented from being clogged.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an ink jet printer as an embodiment of an ink jet recording apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view for explaining the configuration of the ink jet printer according to the first embodiment of the present invention.
[0020]
In this ink jet printer, the recording paper 301 is fed to a portion facing the ink jet head 150 by a paper feed roller 302 and sent via a main body control unit 303 that controls input / output of image data from a connected computer or the like. An image based on the image data processed by the image control unit 304 is formed based on ink being ejected onto the recording paper 301 by the inkjet head 150. After the image is formed, the recording paper 301 is conveyed in the direction of arrow D 1, and after the ink is fixed on the recording paper 301 by the fixing unit 305, the recording paper 301 is discharged onto the paper discharge unit 306. Further, the operation of each of these units is controlled by the control unit 307.
[0021]
The ink jet printer includes a maintenance unit 200 in addition to the above-described units, and the positions of the ink jet head 150 and the maintenance unit 200 can be moved. At the time of printing, the inkjet head 150 and the maintenance unit 200 are positioned as shown in FIG. 1, and an image is printed on the recording paper 301 as described above. That is, it moves upward, and the maintenance unit 200 moves in the direction of arrow D3, that is, forward. The inkjet head 150 is capped by the maintenance unit 200 at the moved position.
[0022]
2-4 is a figure for demonstrating the structure of the inkjet head 150 of the inkjet printer which is the 1st Embodiment of this invention. 2 is a plan view showing the nozzle surface of the inkjet head 150, FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.
[0023]
As shown in FIG. 3, the inkjet head 150 has a configuration in which a nozzle plate 401, a diaphragm 402, a PZT 403, and a ceramic substrate 404 are integrally stacked.
[0024]
The nozzle plate 401 is made of metal or ceramic and has a nozzle 405. The inner surface of the nozzle 405 is subjected to ink repellent treatment, and the inner surface of the nozzle 405 has an ink repellent treatment portion 414. A thin film is used for the diaphragm 402, and the diaphragm 402 is fixed between the nozzle plate 401 and the PZT 403.
[0025]
A plurality of ink channels 407 that store ink 406 and an ink inlet 409 that connects each ink channel 407 to a common ink chamber 408 are formed between the nozzle plate 401 and the vibration plate 402. The common ink chamber 408 is connected to an ink tank (not shown), and the ink 406 in the common ink chamber 408 is supplied to the ink channel 407.
[0026]
A surface of the PZT 403 in contact with the diaphragm 402 is provided with an individual electrode side wiring portion 412 connected to the driver circuit 410 via the flexible wiring 411 and individually connected to the plurality of PZTs 403 in the inkjet head 150, and the ceramic substrate 404. Above, a common electrode side wiring portion 413 connected to the ground and connected in common to a plurality of PZTs 403 in the inkjet head 150 is provided. The individual electrode side wiring portion 412 is connected to the individual electrode in the PZT 403, and the common electrode side wiring portion 413 is connected to the common electrode in the PZT 403.
[0027]
The operation of the ink jet head 150 configured as described above is controlled by the driver circuit 410. A predetermined pulse voltage based on image data sent from a personal computer or the like is applied between the driver circuit 410 and the individual electrode and the common electrode provided in the PZT 403, and the PZT 403 pushes the diaphragm 402. It deforms in the direction of arrow D4 in FIG. The deformation of the PZT 403 is transmitted to the diaphragm 402, the ink 406 in the ink channel 407 is pressurized, and the ink drop 450 flies toward the recording sheet through the nozzle 405.
[0028]
The ink jet head 150 is moved at right angles to the direction in which the nozzles are arranged while the nozzle surface is kept parallel to the recording sheet, and thereby an image based on the image data is printed.
[0029]
In the ink jet head 150 of the present ink jet printer, the position of the ink surface near the nozzle 405 is different between when the image is printed and when it is not printed (when printing is continuously stopped). FIG. 5 is a diagram illustrating the position of the ink surface near the nozzle 405.
[0030]
In the ink jet head 150, the ink liquid level 421 is formed near the opening end near the recording sheet of the nozzle 405 during printing, and an ink drop is ejected. The ink is retreated to the side closer to the inside of 407 to form an ink liquid level 422. In order to stabilize the liquid surface 422 formed at the time of non-printing, the inner surface of the nozzle 405 with which the liquid surface 422 contacts is subjected to ink repellent treatment, and the inner surface of the nozzle 405 has an ink repellent treatment portion 414.
[0031]
Here, Cytop (manufactured by Asahi Glass Co., Ltd.) is applied as the ink repellent treatment, but other fluorine-based resins such as perfluoroacrylate are applied, or eutectoid of fluorine-containing particles and metal. Plating can be used.
[0032]
Such retreat of the ink level is achieved by performing capping as shown in FIG.
[0033]
FIG. 6 is a diagram for explaining capping performed in the ink jet printer. FIG. 6A is a diagram illustrating a state before the sealing portion is pressurized by the cap, and FIG. 6B is a diagram illustrating a state where the sealing portion is pressurized by the cap.
[0034]
A sealing part 432 is formed on the nozzle surface of the inkjet head 150 using an elastic cap 431 during non-printing. In particular, in the present ink jet printer, unlike the conventional ink jet printer, either the cap 431 or the ink jet head 150 is moved to move the cap 431 to the nozzle surface of the ink jet head 150 as shown in FIG. By pressing, the sealing part 432 is brought into a pressurized state. When the sealing portion 432 is in a pressurized state in this way, the liquid level of the ink formed inside the nozzle 405 is changed from the position at the time of printing as shown in FIG. It is retracted toward the inside of the channel 407.
[0035]
As a cap for sealing the nozzle surface, a cap having a different shape from the above can be used. FIG. 7 is a diagram for explaining capping using a cap having a shape different from the cap shown in FIG. FIG. 7A is a diagram illustrating a state before the sealing portion is pressurized by the cap, and FIG. 7B is a diagram illustrating a state where the sealing portion is pressurized by the cap.
[0036]
Here, an elastic cap 433 shaped to cover the entire nozzle surface of the ink jet head 150 during non-printing is used, and either the cap 433 or the ink jet head 150 is moved to form the sealed portion 434. The The sealed portion 434 is in a pressurized state in the same manner as the sealed portion 432 shown in FIG. 6, and when not printed, as shown in FIG. 5, the liquid level of the ink formed inside the nozzle 405 is printed. The ink channel 407 is retracted from the position toward the inside.
[0037]
As described above, the vicinity of the nozzle hole is sealed, pressurized from the nozzle surface toward the inside of the ink channel, and the liquid level of the ink is moved toward the inside of the ink channel, so that the ink jet printer is moved near the nozzle hole when not in use. The ink is not dried, and the nozzle holes are completely prevented from being clogged.
[0038]
Subsequently, an ink jet printer according to a second embodiment of the present invention will be described with reference to FIGS.
[0039]
FIG. 8 is a view for explaining the configuration around the inkjet head 155 of the inkjet printer according to the second embodiment of the present invention.
[0040]
The ink jet printer is provided with an ink jet head 155 corresponding to each color of K, C, M, and Y (black, cyan, magenta, yellow), and printing is performed on a recording sheet. The ink jet printer according to the present embodiment is configured such that the ink supplied to and recovered from each ink jet head 155 passes through different ink flow paths 181 and 182, respectively. When the conveying roller 160 is rotated in the direction of arrow D5, the conveying belt 170 conveys the recording sheet 190 in the direction of arrow D6. As will be described later, a pump is connected to the common ink chamber of the inkjet head 155 via the ink flow paths 181 and 182, and when necessary, the ink flows through the ink flow paths 181 and 182 with the arrows D7 and D7, respectively. It is configured to flow in the direction D8.
[0041]
9 and 10 are diagrams for explaining the configuration of the inkjet head 155. FIG. 9 is a plan view showing the nozzle surface of the inkjet head 155, and FIG. 10 is a sectional view taken along line XX of FIG. Here, the sectional view taken along line IV-IV in FIG. 10 is the same as the sectional view shown in FIG. 9 and 10, the same reference numerals are used for portions having functions equivalent to those of the inkjet head 150 shown in FIGS. 2 to 4.
[0042]
As shown in these drawings, the inkjet head 155 has substantially the same configuration as the inkjet head 150. In particular, the ink inlet 409 has an ink repellent treatment portion 415, and when necessary, the direction of the arrow D7. The ink jet head 150 is different from the ink jet head 150 in that ink can flow.
[0043]
In this ink jet printer as well, as in the first embodiment, the position of the ink liquid level during non-printing is different from that during printing. FIG. 11 is a diagram illustrating the position of the ink liquid level when the image is printed and when the image is not printed.
[0044]
In the ink jet head 155, an ink liquid level 423 is formed in the vicinity of the nozzle surface at the time of printing, and an ink drop is ejected toward the recording sheet. On the other hand, at the time of non-printing, the ink liquid level reaches to the vicinity of the ink inlet 409. Is retracted, and the ink level 424 is formed. In order to stabilize the liquid level 424 formed at the time of non-printing, the ink repellent process in which the same ink repellent process as the ink repellent process part 414 shown in FIG. A portion 415 is provided. Further, when the ink in the common ink chamber 408 is pressurized, the liquid level 424 at the time of non-printing is restored to the liquid level 423 at the time of printing.
[0045]
Such a retreat of the ink surface can be performed by using a pump as shown in FIG.
[0046]
FIG. 12 is a diagram for explaining a configuration of a portion related to ink purging in the ink jet printer.
[0047]
The ink jet printer includes an ink tank 201 for containing ink, a purge pressure pump 202 for discharging ink from the ink tank 201 toward the common ink chamber of the ink jet head 155, and a common ink chamber to the ink tank 201. A purge suction pump 203 for sucking ink toward the ink, a pressure increasing / decreasing pump 204 for discharging air toward the nozzle face of the ink jet head 155 and sucking air near the nozzle face, and unnecessary ink are contained. A waste ink tank 205, valves 206 and 207 for adjusting the flow of ink, and a cap 208 provided with an air communication valve 209 for sealing the inkjet head 155. Moreover, these each part is connected by the flow paths 211-215.
[0048]
In this ink jet printer, as a maintenance of the ink jet head 155, after printing is finished, the ink jet head 155 is first capped by the cap 208 (the state shown in FIG. 12), and the purge pressure pump 202 and the purge suction pump 203 are turned on. Ink purge for ejecting ink from the nozzle 405 is performed. Thereafter, the cap 208 is opened, and the ink in the cap 208 is collected by sucking air by the pressure-reducing pump 204, and the air is sufficiently put in the flow path 215.
[0049]
Next, the inkjet head 155 is capped again by the cap 208, and air is discharged into the ink channel through the nozzles by the air being discharged by the pressure increasing / decreasing pump 204. Note that after ink purging, an operation called wiping is performed to remove ink droplets scattered around the nozzles during ink purging, ink solid matter adhering to the nozzle plate, and paper powder by wiping with a rubber blade (not shown). It is.
[0050]
As a result, the liquid level of the ink in the vicinity of the nozzle 405 at the time of printing can be retracted to the ink inlet 409 as shown in FIG. 11, and the ink does not dry near the nozzle hole when the ink jet printer is not used. Clogging of the nozzle hole is completely prevented.
[0051]
Further, in the present ink jet printer, the following maintenance for collecting bubbles in the common ink chamber of the ink jet head 155 can be performed.
[0052]
After the printing is completed, first, the cap 208 is removed, and the ink flow is stopped by the purge pressure pump 202 (an additional valve may be provided depending on the role of the valve and the type of pump). Subsequently, a negative pressure is generated in the common ink chamber by the purge suction pump 203, and then the valve 206 is opened to suck the ink.
[0053]
Accordingly, in the present ink jet printer, bubbles in the common ink chamber in the ink jet head 155 can be collected.
[0054]
Further, in the ink jet printer, the ink in the ink channel can be removed as follows. FIG. 13 is a diagram for explaining the removal of ink from the ink channel by circulating the ink in the common ink chamber at a high speed.
[0055]
Here, the ink in the common ink chamber is circulated at high speed using the pressurizing pump 202 and the suction pump 203 shown in FIG. When the ink in the common ink chamber is circulated at high speed in this way, the ink in the ink channel is sucked into the common ink chamber 408 by the principle of the aspirator, and the ink is removed from the ink channel (the same configuration as in FIGS. 9 and 10). It is.
[0056]
For example, when the ink is discharged from the ink tank 201 toward the ink jet head 155 by the purge pressure pump 202, if the flow path resistance of the flow path 214 from the ink jet head 155 to the ink tank 201 is sufficiently small, The ink is drawn into the common ink chamber 408, the liquid level near the nozzle 405 during printing retreats, and an ink level 435 is formed.
[0057]
Thereafter, the bubbles 440 in the common ink chamber 408 are carried to the ink tank 201 by gently circulating the ink.
[0058]
In the above description, the liquid level of the ink is retreated to the vicinity of the ink inlet, but the retreat of the liquid level of the ink can be performed to the middle of the ink channel. FIG. 14 is a diagram illustrating the position of the ink liquid level at the time of non-printing when the ink liquid surface recedes up to the middle of the ink channel 407. Here, at the time of printing, as in FIGS. 5 and 11, the position of the ink liquid surface is in the vicinity of the opening end of the nozzle 405 on the recording sheet side, and the ink repellent processing unit 437 is in the vicinity of the liquid surface 436 after the retreat. Provided.
[0059]
In addition to the ink jet head having the shape described above, an ink jet head having the following shape can be used. FIG. 15 is a diagram showing an inkjet head having a shape different from that described above. FIG. 15A is a plan view showing a nozzle surface of the ink jet head, FIG. 15B is an enlarged view of a portion B in FIG. 15A, and FIG. 15C is FIG. It is a CC sectional view taken on the line of FIG.
[0060]
In such an ink jet head as well, the ink repellent processing section 438 is provided in the same manner as described above, and the ink level can be retracted to the ink inlet 409 when not in use.
[0061]
As described above, by retreating the ink surface to the vicinity of the common ink chamber, the ink is not dried near the nozzle hole when not in use. Also, by retreating the ink surface from the nozzle surface to the vicinity of the common ink chamber (inside the ink channel), the concentration of the vaporized ink solvent increases near the ink surface, so that the ink surface is The drying rate by evaporation is slower than when exposed on the surface. As a result, clogging of the nozzle holes can be completely prevented.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view for explaining a configuration of an ink jet printer according to a first embodiment of the present invention.
FIG. 2 is a plan view showing a nozzle surface of the ink jet head according to the first embodiment of the present invention.
3 is a cross-sectional view taken along line III-III in FIG.
4 is a cross-sectional view taken along the line IV-IV in FIG. 3;
FIG. 5 is a diagram illustrating a position of an ink liquid level in the vicinity of a nozzle.
FIG. 6 is a diagram for explaining capping performed by the ink jet printer according to the first embodiment.
7 is a diagram for explaining capping using a cap having a shape different from that of the cap shown in FIG. 6; FIG.
FIG. 8 is a view for explaining a configuration around an inkjet head 155 of an inkjet printer according to a second embodiment of the present invention.
FIG. 9 is a plan view showing a nozzle surface of the inkjet head.
10 is a cross-sectional view taken along line XX of FIG.
FIG. 11 is a diagram illustrating the position of the ink liquid level when an image is printed and when it is not printed.
FIG. 12 is a diagram for explaining a configuration of a portion related to ink purging in the ink jet printer according to the second embodiment.
FIG. 13 is a diagram for explaining ink removal from an ink channel by circulating ink in a common ink chamber at a high speed.
FIG. 14 is a diagram illustrating the position of the ink liquid level at the time of non-printing when the ink liquid level is set back to the middle of the ink channel.
15 is a diagram showing an inkjet head having a shape different from that of the inkjet head shown in FIGS. 2 to 4 or the inkjet head shown in FIGS. 9 and 10. FIG.
[Explanation of symbols]
150 Inkjet head 401 Nozzle plate 402 Diaphragm 403 PZT
404 Ceramic substrate 405 Nozzle 406 Ink 407 Ink channel 408 Common ink chamber 409 Ink inlet 410 Driver circuit 411 Flexible wiring 412 Individual electrode side wiring unit 413 Common electrode side wiring unit 414 Ink repellent processing unit 421 Ink liquid level 422 during printing Ink level during printing 450 Ink drop

Claims (1)

An ink jet recording apparatus that records an image on a recording medium by ejecting ink in an ink channel onto the recording medium from a nozzle provided in the ink channel,
An ink tank for containing ink;
A common ink chamber for supplying ink to the ink channel;
A first flow path for supplying ink from the ink tank to the common ink chamber;
A second flow path for returning ink from the common ink chamber to the ink tank;
A circulation means for circulating ink in a circulation path formed by the ink tank, the first flow path, the common ink chamber, and the second flow path;
When the image is not recorded, the circulation means draws ink in the nozzle in the direction opposite to the ejection direction, so that the ink in the ink channel is sucked into the common ink chamber and removed from the ink channel. As described above, an ink jet recording apparatus that circulates ink in the circulation path.

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