JP4529267B2 - Inkjet printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet printer having a configuration in which a filter for removing foreign matters contained in ink is arranged in an ink passage for supplying ink to an ink jet head. More specifically, the present invention relates to an ink jet printer that can avoid adverse effects such as defective printing caused by trapping bubbles in a filter.
[0002]
[Prior art]
In an ink jet printer, if foreign matter is mixed in the ink supplied from the ink tank to the ink jet head, the ink nozzles of the ink jet head may be clogged, which may cause problems such as defective ink ejection. Therefore, a foreign matter removing filter is disposed in the ink supply path in the vicinity of the ink jet head to prevent the foreign matter from entering the ink jet head together with the ink.
[0003]
[Problems to be solved by the invention]
Here, a removable ink cartridge or the like is used as the ink tank. If the emptied ink cartridge is removed when replacing the ink cartridge, the ink supply system is opened to the atmosphere, so that bubbles may enter the ink supply system. When the ink filling operation is performed from the ink cartridge toward the ink jet head after the ink cartridge replacement, the invading bubbles are also sent to the ink jet head side together.
[0004]
There is no problem if the bubbles are discharged to the outside through the respective ink nozzles of the ink jet head, but they may be trapped by the filter disposed in the ink supply path and stay there. When bubbles are trapped in the filter, the bubbles gradually grow with the bubbles as nuclei. As a result, the following adverse effects occur.
[0005]
First, ink supply becomes unstable due to bubbles trapped in the filter. As a result, when a required amount of ink is not supplied to the ink nozzle, ink droplet ejection failure occurs. Furthermore, when bubbles trapped in the filter expand, ink droplets cannot be ejected.
[0006]
An object of the present invention is to propose an ink jet printer which can automatically eliminate bubbles trapped by a filter.
[0007]
[Means for Solving the Problems]
The present invention relates to an ink jet head, an ink intake port formed in the ink jet head, a filter disposed on the upstream side of the ink intake port, and a connection block located above the filter and having an ink passage to the filter. An ink supply pipe portion in which a cross-sectional shape of the ink passage is formed substantially constant along an ink flow direction, and is positioned between and connected to the ink supply pipe portion and the filter. A connection block having an ink passage connection portion extending in the direction of the filter, and an internal volume of the ink passage connection portion is substantially equal to or less than a volume of a sphere inscribed in the ink supply pipe portion. Features.
[0008]
In the present invention, when the bubbles accumulated in the ink passage connection portion are separated from the upper surface of the filter to become a spherical bubble sphere, the bubble sphere is not larger than the size that can pass through the ink supply pipe portion. Therefore, the bubbles trapped on the upper surface of the filter are automatically discharged upward via the ink supply pipe portion by buoyancy acting on the bubbles.
[0009]
Here, it is preferable that the ink passage connection portion has a substantially truncated cone shape. From the above configuration, since the bubbles above the filter have a tapered inner peripheral surface, the bubbles released from the upper surface of the filter rise to the ink supply pipe part side along the tapered inner peripheral surface, The ink is reliably discharged from the ink passage.
[0010]
Further, it is more preferable that the inner peripheral surface forming the ink passage connecting portion is formed of a curved surface bulging inward than the tapered shape.
[0011]
Further, the connection block is preferably attached so that the ink passage connection portion and the ink supply pipe portion are substantially vertical. In this case, the bubble sphere includes the ink passage connection portion and the ink supply pipe. The inner peripheral surface forming the part is reliably discharged without being hindered from rising.
[0012]
Furthermore, it is desirable that the ink supply pipe portion is substantially cylindrical. As a result, the shape of the rising bubble sphere is not disturbed by buoyancy, and the ink is smoothly discharged through the ink supply tube.
[0013]
Furthermore, it is desirable that the filter is disposed at the ink intake port. From the above configuration, air bubbles entering the ink jet head can be reliably prevented when the ink jet head is arranged near the ink jet head.
[0014]
In the present invention, it is also effective to have a bubble pool for storing bubbles rising above the ink supply pipe above the connection block. If it does in this way, the bubble caught by the filter upper part will leave | separate from the said filter upper surface with a buoyancy, will float through a connection block, and will be stored in the bubble pool above it. As a result, it is possible to avoid the adverse effect that the bubbles once removed from the upper surface of the filter are again flowed to the filter through the ink supply pipe portion by the ink flow and trapped there.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
First Embodiment Hereinafter, a first embodiment of an ink jet printer to which the present invention is applied will be described with reference to FIGS.
[0016]
FIG. 1 is an overall configuration diagram of the ink jet printer of this example. As shown in this figure, an ink jet printer 1 includes an ink jet head 2, a carriage 3 carrying the ink jet head 2, and a belt type for reciprocating the carriage 3 in the main scanning direction (direction of arrow A). A drive mechanism 4 and a guide shaft 5 for the carriage 3 are provided.
[0017]
The ink nozzle surface of the inkjet head 2 is directed downward, and a platen roller 6 is disposed below the ink nozzle surface so as to face the ink nozzle surface. A desired print can be formed on the surface of the recording paper 7 by the inkjet head 2 while the recording paper 7 is conveyed in the sub-scanning direction (arrow B) by the platen roller 6.
[0018]
The ink pressure attenuator 8 shown in FIG. 2 is also mounted on the carriage 3, and the ink in the ink cartridge 10 that is detachably attached to the ink cartridge attachment portion 9 is supplied to the ink tube 11 and the ink pressure attenuator 8. Via the inkjet head 2.
[0019]
A waste ink recovery mechanism 13 is disposed at a position outside the printing area in the main scanning direction where printing is performed by the inkjet head 2. The waste ink recovery mechanism 13 includes a cap 14 capable of capping the ink nozzle surface of the inkjet head 2, and a suction pump that suctions and recovers the waste ink recovered by the cap 14 into a waste ink tank 16 via a waste ink tube 15. 17 is provided.
[0020]
Next, FIG. 2 is a configuration diagram showing an ink supply mechanism of the ink jet printer 1, and FIG. 3 is a sectional view thereof. Referring to these drawings, the ink supply mechanism 20 is basically composed of an ink cartridge 10, an ink tube 11, and an ink pressure attenuator 8.
[0021]
The ink cartridge 10 includes a flat cuboid-shaped hard case 101 and a flexible ink bag 102 that is housed in the case 101 and in which ink is sealed. An ink outlet 103 is formed in the ink bag 102, and the ink outlet 103 protrudes outward from the case 101.
[0022]
An ink supply needle 112 is attached to one end of the ink tube 11, and the ink supply needle 112 is inserted into the ink outlet 103 of the ink cartridge 10. The ink supply needle 112 is fixed to the printer 1 and is inserted into and removed from the ink outlet 103 by the attachment / detachment operation of the ink cartridge 10.
[0023]
On the other hand, the other end of the ink tube 11 is connected to the ink pressure attenuator 8.
[0024]
As shown in FIG. 3, the ink pressure attenuator 8 includes a flat cup-shaped hard case body 81 and a soft film 82 attached to the case body 81 so as to close the opening of the case body 81. And a leaf spring 83 attached to the inner surface of the film 82, and a pressure attenuation chamber 80 is formed between the case body 81 and the film 82.
[0025]
An ink inlet 84 and an ink outlet 85 are formed in the case body 81. The ink tube 11 is connected to the ink inlet 84, and the ink outlet 85 communicates with the upper end of the ink outlet path 86 formed in the case body 81. The lower end of the ink outflow path 86 is a large-diameter head connection portion 87.
[0026]
A predetermined amount of ink 40 is stored in the pressure attenuation chamber 80 of the ink pressure attenuator 8 having this configuration. As the internal pressure of the pressure attenuation chamber 80 increases or decreases, the film 82 elastically deforms the leaf spring 83 outward or inward, and its volume increases or decreases. Due to the displacement of the film 82, the internal pressure of the pressure attenuation chamber 80 is held constant. Therefore, even if the ink pressure on the ink inlet 84 side fluctuates, the ink supply pressure supplied from the ink outlet 85 to the inkjet head 2 side is held constant.
[0027]
Next, referring to FIG. 3 and FIG. 4, the inkjet head 2 includes an ink chamber 201 that stores ink, and an ink intake port 202 for taking ink into the ink chamber 201. Ink is supplied from the chamber 201 toward each ink nozzle 203. As described above, the inkjet head 2 is mounted on the carriage 3 such that the ink nozzle surface 204 is in a downward posture, and the ink intake port 202 is open to the unit case upper wall 210 of the inkjet head 2.
[0028]
On the unit case upper wall 210, a connection block 21 having an ink supply pipe portion 23 formed with a substantially constant inner diameter d connected to the ink pressure attenuator 8 and a connection portion 22 having a substantially frustoconical shape is connected to the ink intake. It is attached corresponding to the mouth 202.
[0029]
The upper end portion of the ink supply pipe portion 23 is inserted into the head connection portion 87 by deforming the packing 88 so that ink does not leak from the lower side.
[0030]
Further, a filter plate 24 for removing foreign matter from the ink supplied from here to the ink jet head 2 is sandwiched between the connection block 21 and the unit case upper wall 210 at a position directly above the ink intake port 202. ing.
[0031]
Here, the structure of the ink passage connection portion in which the filter 24 is disposed will be described in more detail. The ink passage formed inside the connection portion 22 having an inner truncated cone shape has a large diameter lower end portion 221 communicating with the ink intake port 202 and a small diameter communicating with the ink supply pipe portion 23. An upper end portion 223, a filter attachment portion 224 formed on the lower end portion 221, and a truncated cone-shaped ink passage connection portion 222 extending from the filter attachment portion 224 to the upper end portion 223 are provided.
[0032]
In this example, the internal volume of the ink passage connection portion 222 between the filter upper surface 24 a and the upper end portion 223 is equal to or smaller than the inscribed sphere volume of the ink supply pipe portion 23 communicating with the upper end portion 223. Is set. For example, the internal volume of the ink passage connection portion 222 is set to be the same as the inscribed sphere volume of the ink supply pipe portion 23.
[0033]
In the inkjet printer 1 configured as described above, bubbles may enter the ink supply passage when the ink cartridge 10 is replaced. Bubbles that have entered the ink supply passage may reach the filter 24 by an ink suction operation in which the cap 14 is attached to the ink nozzle surface 204 of the inkjet head 2 and suctioned by the suction pump 17. The bubbles 30 reaching the filter 24 are captured by the filter upper surface 24a, and are attached to the filter upper surface 24a in a flat hemispherical state as shown in FIG.
[0034]
When the ink suction is stopped, the bubbles attached to the filter upper surface 24a become spherical due to the surface tension. Since the internal volume of the frustoconical passage portion 222 is set as described above, the diameter D of the bubble 30A accumulated in a spherical shape has a diameter D of the ink supply pipe portion 23 extending substantially vertically upward. It will never be greater than the inner diameter d. Therefore, the bubble 30A is lifted along the inner peripheral surface of the frustoconical ink passage connecting portion 222 by the buoyancy of the ink 40, and floats on the ink supply pipe portion 23 continuing to the upper end thereof, and the filter 24 Is discharged from the connecting portion 22 to which is attached.
[0035]
As a result of an experiment in which the specific gravity of the ink 40 is 1.06 and the inner diameter of the ink supply pipe portion 23 is 1.6 mm, the inner volume of the ink passage connection portion 222 is inscribed in the ink supply pipe portion 23 communicating with the upper end portion 223. It was confirmed that the bubbles surely moved up to 1.1 times the sphere volume, moved or not moved at 1.2 times, and hardly moved at 1.3 times.
[0036]
As described above, in this example, the bubbles 30 trapped on the filter upper surface 24a float from the filter upper surface 24a by buoyancy, and further float above the ink supply pipe portion 23 extending substantially vertically above. Therefore, it is possible to avoid the bubbles 30 from staying on the upper surface of the filter.
[0037]
Further, in this example, since the ink passage connection portion 222 from the filter upper surface 24 a to the ink supply pipe portion 23 has a truncated cone shape, the bubbles 30 captured by the filter upper surface 24 a are tapered in the ink passage connection portion 222. It is possible to rise quickly along the inner peripheral surface. Accordingly, it is possible to avoid the adverse effect of bubbles trapped on the step surface and staying there, as in the case where a horizontal step surface or the like in a downward state is formed in the ink passage connection portion.
[0038]
Here, if a bubble pool is formed above the ink supply pipe portion 23 that is arranged substantially vertically to store the air bubbles 30A that have risen, such bubbles will enter the filter 24 side again. Since it can prevent, it is preferable.
[0039]
In the present embodiment, a bubble pool 89 is provided above the ink inlet 84 of the pressure attenuation chamber 80. In this case, even if the ink in the ink jet head 2 is sucked from the ink nozzle 203, the ink in the pressure attenuation chamber 80 flows downward from the ink inlet 84 to the ink jet head 2. Air bubbles are not drawn into the filter 24 side.
[0040]
Second Embodiment Next, a second embodiment of the connection block will be described with reference to FIG.
FIG. 6 corresponds to FIG. 4 in the first embodiment described above, and other configurations and functions are the same as those in the first embodiment. In addition, parts having the same or the same functions as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
[0041]
1st Embodiment is that the inner wall of the connection part 25 of the connection block 21a is formed in the curved surface.
[0042]
Here, the structure of the ink passage connection portion in which the filter 24 is disposed will be described in more detail. The ink passage formed in the connection portion 25 having a curved surface is a large-diameter lower end portion 221 communicating with the ink intake port 202 and a small diameter communicating with the ink supply pipe portion 23. The upper end portion 223 of the filter, the filter mounting portion 224 formed at the lower end portion 221, and the ink formed with a curved surface with a curved curve that becomes narrower as the inner wall bulges inward from the filter mounting portion 224 to the upper end portion 223. And a passage connecting portion 222.
[0043]
In this example, the internal volume of the ink passage connecting portion 222 between the filter upper surface 24a and the upper end portion 223 is substantially equal to or less than the inscribed sphere volume of the ink supply pipe portion 23 communicating with the upper end portion 223. Is set to For example, the internal volume of the ink passage connection portion 222 is set to be the same as the inscribed sphere volume of the ink supply pipe portion 23.
[0044]
According to the above configuration, substantially the same effect as that of the first embodiment described above can be obtained, and further an effect can be obtained in which bubbles are more easily separated from the upper surface of the filter than the first embodiment.
[0045]
Third Embodiment Next, a third embodiment of the connection block will be described with reference to FIG.
FIG. 7 corresponds to FIG. 4 in the first embodiment described above, and other configurations and functions are the same as those in the first embodiment. In addition, parts having the same or the same functions as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
[0046]
The first embodiment is that the ink supply pipe portion 23 is formed in a step shape so that the inner wall of the connection portion 26 of the connection block 21b can be easily manufactured.
[0047]
Here, the structure of the ink passage connection portion in which the filter 24 is disposed will be described in more detail. The ink passage formed inside the cylindrical connection portion 26 has a large-diameter lower end portion 221 communicating with the ink intake port 202 and a small-diameter upper end portion 223 communicating with the ink supply pipe portion 23. And a filter attachment portion 224 formed at the lower end portion 221 and a columnar ink passage connection portion 222 extending from the filter attachment portion 224 to the upper end portion 223.
[0048]
In this example, the internal volume of the ink passage connecting portion 222 between the filter upper surface 24a and the upper end portion 223 is substantially equal to or less than the inscribed sphere volume of the ink supply pipe portion 23 communicating with the upper end portion 223. Is set to For example, the internal volume of the ink passage connection portion 222 is set to be the same as the inscribed sphere volume of the ink supply pipe portion 23.
[0049]
According to the above configuration, substantially the same effect as that of the first embodiment described above was obtained.
[0050]
Fourth Embodiment A fourth embodiment of the connection block will be described with reference to FIG. FIG. 8 corresponds to FIG. 4 in the first embodiment described above, and other configurations and functions are the same as those in the first embodiment. In addition, parts having the same or the same functions as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
[0051]
In the connection block 21c of the present embodiment, the inner wall of the connection portion 26 is a combination of the shapes of the first and third embodiments.
[0052]
Here, the structure of the ink passage connection portion in which the filter 24 is disposed will be described in more detail. The ink passage formed inside the connection portion 27 having a shape obtained by combining the truncated cone shape and the columnar shape communicates with the large-diameter lower end portion 221 communicating with the ink intake port 202 and the ink supply pipe portion 23. The upper end portion 223 having a small diameter, the filter mounting portion 224 formed at the lower end portion 221, and the ink passage connection having a shape obtained by combining the truncated cone shape and the columnar shape extending from the filter mounting portion 224 to the upper end portion 223. Part 222.
[0053]
In this example, the internal volume of the ink passage connecting portion 222 between the filter upper surface 24a and the upper end portion 223 is substantially equal to or less than the inscribed sphere volume of the ink supply pipe portion 23 communicating with the upper end portion 223. Is set to For example, the internal volume of the ink passage connection portion 222 is set to be the same as the inscribed sphere volume of the ink supply pipe portion 23.
[0054]
According to the above configuration, substantially the same effect as that of the first embodiment described above was obtained.
[0055]
The present invention is not limited to the above-described embodiment, and various changes can be made.
[0056]
For example, in the present embodiment, the ink nozzle surface of the inkjet head 2 is directed downward. However, the ink nozzle surface is not limited to that direction. For example, the ink jet surface may be ejected laterally.
[0057]
In this embodiment, the connection block is attached so that the ink supply pipe portion of the connection block is substantially vertical. However, the connection block is not limited to be vertical, and the angle formed by the supply pipe portion and the horizontal plane is about 45 degrees. However, bubbles are more likely to float away from the upper surface of the filter, and the effect is greater when the angle is vertical or near vertical.
[0058]
Furthermore, in this embodiment, the filter is installed at the ink intake port into the ink chamber of the ink jet head. However, the present invention is not limited to this. For example, the filter may be arranged in the ink flow path away from the ink jet head. However, it is easier to prevent bubbles from entering the ink jet head when it is arranged near the ink jet head.
[0059]
Furthermore, in the present embodiment, the case where the ink supply pipe portion of the connection block is a circular cylinder having a circular cross section has been described, but the cross section may be rectangular, and in this case, the contents of the ink passage connection portion The same effect can be obtained by setting the product to be equal to or less than the substantially spherical volume inscribed in the ink supply pipe section.
[0060]
【The invention's effect】
As described above, in the ink jet printer of the present invention, even if air bubbles are captured by the filter disposed in the ink supply path in order to remove foreign matter from the ink supplied to the ink jet head, such air bubbles are not generated. The filter is automatically separated from the upper surface of the filter by buoyancy and discharged to a portion other than the ink supply path where the filter is disposed.
[0061]
Therefore, it is possible to avoid problems such as instability of the ink supply amount caused by trapping bubbles in the filter and staying there, and associated printing failure or printing failure. Therefore, an ink jet printer with high printing reliability can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an ink jet printer to which the present invention is applied.
FIG. 2 is a configuration diagram illustrating the ink supply mechanism of FIG. 1;
3 is a cross-sectional view of the ink supply mechanism of FIG.
4 is a partial explanatory view showing an ink passage of a filter arrangement portion in the ink supply mechanism of FIG. 2; FIG.
FIG. 5 is an explanatory diagram showing a state where bubbles are released from the upper surface of the filter and floated in FIG. 4;
FIG. 6 is a partial explanatory view showing an ink passage of a connection block portion in a second embodiment of the present invention.
FIG. 7 is a partial explanatory view showing an ink passage of a connection block portion in a third embodiment of the present invention.
FIG. 8 is a partial explanatory view showing an ink passage of a connection block portion in a fourth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Inkjet head 8 Ink pressure attenuator 9 Ink cartridge mounting part 10 Ink cartridge 11 Ink tube 20 Ink supply mechanism 21 Connection block 22 Connection part 23 Ink supply pipe part 24 Filter 201 Ink chamber 202 Ink intake port 221 Lower end part 222 Ink passage connection part 223 Upper end part 30, 30A Bubble 40 Ink

Claims (7)

An inkjet head;
An ink intake port formed in the inkjet head;
A filter disposed upstream of the ink intake port;
An ink supply pipe section, which is located above the filter and has an ink passage to the filter, the cross section of the ink passage being substantially constant along the direction of ink flow; and the ink A connection block having an ink passage connection portion located between the supply pipe portion and the filter and connected and having a cross-sectional shape extending in the direction of the filter;
An ink jet printer according to claim 1, wherein an inner volume of the ink passage connection portion is substantially equal to or less than a volume of a sphere inscribed in the ink supply pipe portion.   The ink jet printer according to claim 1, wherein the ink passage connection portion of the connection block has a substantially truncated cone shape. Inner peripheral surface, an ink jet printer according to claim 1, characterized in that it is formed from a bulged inwardly curved surface forming the ink passage connecting portion.   4. The ink jet printer according to claim 1, wherein the connection block is attached so that the ink passage connection portion and the ink supply pipe portion are substantially vertical. 5.   5. The ink jet printer according to claim 1, wherein the ink supply pipe portion has a substantially cylindrical shape.   The inkjet printer according to claim 1, wherein the filter is disposed in the ink intake port.   7. The ink jet printer according to claim 1, further comprising: a bubble pool for storing bubbles rising up the ink supply pipe above the connection block. 8.

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