JPH10272770A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively remove air bubbles easy to remain in the vicinity of the final end of a supply channel at the time of the initial introduction of ink by purging in an ink jet head constituted so that the ink introduced into the supply channel within a manifold is supplied to a plurality of channels formed in an arranged state in an actuator and the ink in the channels is ejected from nozzles as liquid droplets by driving the actuator. SOLUTION: The width of the terminal part of a supply channel 16 is made narrower toward the final end thereof. By this constitution, an air bubble 39a is brought to a position extremely approaching the inlet end of any channel 6 present in the vicinity of the final end and, if purging is executed at the time of the initial introduction of ink, the air bubble can be easily and effectively removed through any channel 6 present in the vicinity of the final end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head provided in an ink jet type recording apparatus, and more particularly to an improvement in an ink flow path provided in an ink jet head.

[0002]

2. Description of the Related Art There is an ink jet recording apparatus as a recording apparatus having a relatively simple structure and capable of easily performing high-speed printing and high-quality printing. An ink jet recording apparatus that is of interest to the present invention will be described with reference to FIGS. 1 to 6 are also referred to for describing an embodiment of the present invention.

FIG. 1 is a perspective view schematically showing the entirety of an ink jet recording apparatus 1. A printing mechanism 2 and a purge device 3 are incorporated in the inkjet recording device 1. The main part of the printing mechanism 2 is shown in FIG. As shown in FIG. 2, the printing mechanism 2 includes an inkjet head 4 (not shown in FIG. 1) and an ink cartridge 5 that is detachably mounted on the inkjet head 4 to supply ink to the inkjet head 4. I have.

In the ink jet recording apparatus 1, FIG.
As shown by “5a”, “5b”, “5c” and “5d”, four ink cartridges 5 are mounted to supply inks of cyan, magenta, yellow and black to achieve colorization. Accordingly, four ink jet heads 4 are provided corresponding to the four ink cartridges 5.

FIG. 3 shows one ink jet head 4
Is shown in a perspective view. FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3, and FIG. 5 is a sectional view taken along the line VV in FIG. Inkjet head 4
Is composed of an actuator 7 in which a plurality of channels 6 containing ink are formed in an aligned state, and a manifold 8 for supplying ink from the ink cartridge 5 to each channel 6.

The actuator 7 changes the volume in a desired channel 6 by utilizing, for example, deformation when an electric field is applied to the piezoelectric ceramic. When the volume decreases, the ink in the channel 6 is ejected from the nozzle 9 as droplets. On the other hand, when the volume is increased, the ink from the ink cartridge 5 and the manifold 8 is introduced into the channel 6. The nozzle 9 is provided with a small hole 10 communicating with the outlet end of each channel 6.

Preferably, a dummy groove 11 is formed in the actuator 7 so as to extend in parallel with the channel 6 so as to sandwich each channel 6. Dummy groove 1
Numeral 1 is for making it easier to change the volume of each channel 6 due to the deformation of the piezoelectric ceramic described above, and is closed on the manifold 8 side so that ink is not introduced into the inside.

This actuator 7 is shown in FIGS.
As shown in FIG. 2, two substrates 12 and 13 for forming the channel 6 and the dummy groove 11 as described above, respectively.
And a center plate 14 sandwiched between the substrates 12 and 13. Therefore, in the actuator 7, the plurality of channels 6 are arranged in an aligned state while forming two rows.

[0009] The manifold 8 is joined to the actuator 7 on the inlet end side of the channel 6. The manifold 8 is provided with a supply path 16 that extends in the direction in which the plurality of channels 6 are aligned and that opens in common to each inlet end of the channel 6. The supply path 16 is formed along each column of the channel 6, as shown in FIGS. As shown in FIG. 6, the two rows of supply paths 16 are integrated with each other at the upper part, and communicate with the introduction port 21 connected to the ink cartridge 5. In addition,
A part of FIG. 6 also includes a configuration employed in the embodiment of the present invention.

As shown in FIG. 2, the manifold 8 has mounting pieces 17 and 18 formed at both ends thereof. The manifold 8 is positioned while the actuator 7 is sandwiched between the mounting pieces 17 and 18. By applying an adhesive (not shown) in this state, the actuator 7 and the manifold 8 are fixed in a liquid-tight manner. These integrated actuator 7 and manifold 8
The inkjet head 4 having the
And is held by the carriage 20 shown in FIG.

As shown in FIG. 2, the ink jet head 4 is arranged at an angle of about 45 degrees with the nozzle plate 9 down and the manifold 8 up. At this time, the manifold 8 is arranged such that the supply path 16 continues downward from the introduction port 21 with the introduction port 21 at the top. In addition,
The inkjet head 4 can be placed horizontally or vertically downward.
It is desirable that the supply path 16 be disposed below with 1 being on top.

Referring again to FIG. 2, the manifold 8
The above-described ink cartridge 5 is detachably attached to an introduction port 21 communicating with the supply path 16 via a seal member 22 made of rubber and an adapter 23. A filter 24 is provided at the inlet 21, while a filter 26 is provided at the outlet 25 of the ink cartridge 5. Ink is supplied from the ink cartridge 5 to the manifold 8 through these filters 24 and 26. You.

As shown in FIG. 1, the carriage 20 is held so as to be able to linearly reciprocate along a guide shaft 27 and a guide rail 28, and is connected to an endless belt 31 stretched over pulleys 29 and 30. . Therefore, when one pulley, for example, the pulley 30 is driven to rotate by a motor (not shown), the carriage 20 reciprocates linearly.

On the other hand, the recording paper 32 indicated by a two-dot chain line in FIG. 1 is fed in the direction of arrow 35 according to the rotation of the platen roller 33 in the direction of arrow 34 by a paper feed mechanism (not shown). Thus, the ink jet recording apparatus 1
In, the movement of the carriage 20 and the movement of the recording paper 32 cooperate with each other, and the ink jet head 4 ejects ink to a desired area on the recording paper 32 to achieve desired printing.

The above-described purge device 3 is provided on the side of the platen roller 33 so as to face the position of the inkjet head 4 in the reset state. During use, the ink jet head 4 may cause non-ejection due to generation or residual air bubbles inside the ink jet head 4 or adhesion of ink to the ejection surface. The purging device 3 generates a negative pressure by the pump 37 when the cap 36 covers the ejection surface of the inkjet head 4 in the vicinity of the inkjet head 4, and sucks a predetermined amount of ink inside the inkjet head 4 together with bubbles. Then, the ink is sent to the storage section 38, whereby the above-described inconvenience is solved, and the ink jet head 4 is restored to a favorable ejection state.

[0016]

FIG. 11 is an enlarged view of a portion corresponding to portion VIII of FIG.
In the structure considered by the applicant, the manifold 8 of the actuator 7 provided in the inkjet head 4 is used.
The part of the joining surface to the is shown enlarged. Referring to FIG. 11, when the ink cartridge 5 is replaced, the initial introduction of the ink into the inkjet head 4 is performed by sucking the ink from the ink cartridge 5 to the inkjet head 4 using the purge device 3. ,
At this time, the air is also sucked together, and air is generated near the final end of the supply path 16 (the end farthest from the inlet 21).
Tends to remain. In particular, if the inkjet head 4 is left unused, the bubbles 39a
Grows. The bubbles 39a remaining near the final end of the supply path 16 are relatively difficult to remove even if purging is performed.
In many cases, non-ejection of ink occurs in the channel 6 communicating with the vicinity of the final end of the ink. As shown in FIG.
In the case where the supply path 16 is formed parallel to the final end, not only the position where the bubble 39a faces the channel 6 but also
It is also generated at a shifted position, and it is very difficult to remove by suction by the purge device 3.

It is an object of the present invention to provide an ink jet head which can solve the above-mentioned problems.

[0018]

SUMMARY OF THE INVENTION The present invention is directed to an actuator and a channel, wherein a plurality of channels for accommodating ink are formed in an aligned state, and the actuator is driven to eject ink in the channels as droplets from nozzles. A supply passage extending in the alignment direction of the plurality of channels and commonly opening to each of the inlet ends of the channels, for supplying ink to the respective channels. In order to solve the above-mentioned technical problem, the width of the terminal end of the supply path is set to be equal to the width of the final end of the supply path. It is characterized by being narrower as going to.

As described above, when the width is gradually reduced at the end of the supply path, the air bubbles remaining there are brought to a position very close to the inlet end of one of the channels near the final end. Can be. According to a second aspect of the present invention, in the first aspect of the present invention, the deepest portion of the supply path is located at a position shifted from a position where the center line of the channel passes.

Such a characteristic configuration regarding the position of the deepest part of the supply path is such that the cross-sectional area of the supply path is kept substantially the same as compared with the case where the deepest part is located at the position where the center line of the channel passes. Or, without too much, increasing the distance between the deepest part and the inlet end of the channel so that even if the deepest bubble grows at a similar rate, the outer surface of the bubble will remain at the inlet end of the channel. However, when this characteristic configuration is adopted, air bubbles remaining at the deepest portion are undesirably moved away from the inlet end of the channel. As a result, it is more difficult to remove bubbles by purging. Therefore, when the characteristic configuration described in claim 2 is adopted, it is particularly advantageous to gradually reduce the width at the end of the supply path as described in claim 1,
This allows the bubble located at the terminal end to be closer to the inlet end of the channel, so that the bubble can be easily removed by purging.

According to a third aspect of the present invention, in the second aspect of the present invention, the deepest part at the end of the supply path is closer to the position where the center line of the channel passes as it approaches the final end of the supply path. It is characterized in that it has a form extending to When the above-described form is given to the deepest part at the end of the supply path in this way, bubbles remaining at the end of the supply path tend to be located at the deepest part, It is easier to remove bubbles by purging.

According to a fourth aspect of the present invention, in the first aspect of the present invention, a plurality of channels are formed in a plurality of rows and are aligned in each row, and the supply path is It is characterized by being formed along each column of a plurality of channels. In the inkjet head in which a plurality of channels are formed in a plurality of rows and are aligned in each row as described above, when the supply path is formed along each row of the plurality of channels, Since the cross-sectional area cannot be so large, it is significant that bubbles can be effectively removed as described in claim 1.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, FIGS.
Is also for describing the inkjet head 4 according to an embodiment of the present invention. A general description of the ink jet head 4 will be omitted from the description given above with reference to FIGS. 1 to 6 in order to clarify the background of the present invention, and will not be repeated here.

In this embodiment, first, as shown in FIG. 7, a positional relationship between the inlet end of the channel 6 on the actuator 7 side and the supply path 16 on the manifold 8 side is employed. FIG. 7 shows part VI of FIG.
It is an enlarged view of I, and has shown the supply path 16 shown by the solid line in FIG. FIG. 10 is a diagram corresponding to FIG. 7 and shows a structure considered earlier by the present applicant, and shows a supply path 16 indicated by an imaginary line in FIG.

Referring to FIG. 7, the supply path 16 on the manifold 8 side has its deepest portion 40 located at a position shifted from the position where the center line 41 of the channel 6 on the actuator 7 passes. In particular, in this embodiment, channel 6
The deepest part 40 is shifted to a position that does not face the entrance end. That is, the inner wall of the supply path 16 facing the inlet end of the channel 6 is inclined at an acute angle with the center line 41 of the channel 6 and continues to the deepest portion 40. The deepest portion 40 extends parallel to the row of channels 6 except for the channel 6 farthest from the inlet 21 as described later.

As described above, according to this embodiment, FIG.
0, or as shown by the imaginary line in FIG. 5, while maintaining the cross-sectional area of the supply channel 16 substantially the same as when the deepest portion is located at the position where the center line of the channel 6 passes, or Without increasing the depth, the deepest part 40
And the distance between the inlet end of the channel 6 can be increased. Therefore, as shown by the broken line and the solid line in FIG. 7, when the bubble 39 located at the deepest part 40 grows, even if the growth proceeds at the same speed as that shown by the imaginary line in FIG. The period until the outer surface reaches the inlet end of the channel 6 can be made longer.

For this reason, the bubble 39 can be prevented from being drawn into the channel 6 for a relatively long period of time, so that a good printing state can be maintained for a long time. Further, the frequency of the required purge can be reduced, the efficiency of the printing operation can be increased, and the burden on the maintenance system including the purge device 3 shown in FIG. 1 can be reduced. Further, since the amount of ink wasted by purging can be reduced, the amount of ink that can be used for the original printing can be increased.

FIG. 8 shows a characteristic configuration of the present invention in this embodiment. FIG. 8 shows a part of a joint surface of the actuator 7 with the manifold 8. In FIG. 8, a region where the manifold 8 contacts the actuator 7 is hatched.
The position of the deepest portion 40 of the supply path 16 is indicated by a dashed line.

The characteristic structure shown in FIG. 8 is for solving the following problem. As described above, generally, when ink is initially introduced, air bubbles tend to remain near the last end of the supply path, and the air bubbles that remain in the vicinity of the last end of the supply path are purged. Even so, it is relatively difficult to remove,
As a result, non-ejection of ink often occurs in a channel communicating with the vicinity of the end of the supply path.

The above tendency is observed when the deepest portion 40 of the supply path 16 is wider and flatter than the channel 6,
As shown in FIG.
Appear more remarkably when it is located at a position shifted from the position through which the center line 41 passes. Because, as mentioned above,
The air bubbles 39 are likely to remain at the position of the deepest portion 40, but in the former case, air bubbles may be generated at a position far from the inlet end of the channel 6, and in the latter case, they are surely kept away from the inlet end of the channel 6. Because it is.

In this embodiment, as shown in FIG. 8, at the end of the supply path 16, the width of the supply path 16 becomes narrower toward the final end, and furthermore, the deepest part of the supply path 16 40 extends closer to the position where the center line 41 of the channel 6 passes toward the final end of the supply path 16. Therefore, the shape of the supply path 16 corresponding to the channel 6 near the final end is substantially the same as in FIG.

FIG. 8 also shows bubbles 39a remaining near the last end of the supply path 16. This bubble 39
a remains at the position of the deepest part 40 of the supply path 16 similarly to the bubble 39 shown in FIG. 7, but due to the gradually narrowing of the width at the end of the supply path 16, 39a is brought very close to the inlet end of any channel 6 near the last end. In particular, in this embodiment, the deepest portion 40 of the supply path 16 is
As one goes to the last end of channel 6, the center line 41 of channel 6
Extends closer to the position where
As a result of 9a being brought to the position of the deepest part 40, the bubble 39a can be brought more reliably to a position very close to the inlet end of the channel 6.

Therefore, the bubbles 39a remaining in the vicinity of the final end of the supply path 16 can easily pass through any one of the channels 6 near the final end if the purging is performed during the initial introduction of the ink. And can be effectively removed. According to the experiment of the present inventor, as shown in FIGS. 8 and 9, the bubble 39 a is not only difficult to reach the state of contact with the final end face of the supply path 16, but also has a spherical surface as shown in FIG. 10. Since a gap is formed between the flat surface and the flat surface, an ink flow path is secured in the channel 6 at the final end of the supply path 16 as long as bubbles do not grow significantly. However, as shown in FIG.
The growth of the bubbles 39a tends to extend to the upstream side of the supply path 16, and often closes the channel 6 before closing the channel 6 at the final end. For this reason, by the purge at the time of the initial introduction of the ink, it is possible to early remove the air bubbles that cause the blockage.

Note that, as shown in FIG.
Of the inclined surface 2 at the end on the supply path 16 side so as to gradually increase the cross-sectional area toward the supply path 16.
1a. This is because when the ink is initially introduced into the inkjet head 4 from the ink cartridge 5, the ink violently collides with the end face of the inkjet head 4 on the manifold side to generate bubbles. This is to prevent the flow velocity from dropping. Thus, the number of bubbles entering the supply path 16 can be reduced as much as possible, and the configuration according to the present embodiment can be made more effective.

In the specific design of the form of the end portion of the supply path 16 as described above, the wettability of the material constituting the manifold 8, the surface tension of the ink, the final end of the supply path 10 and the endmost channel 6 Factors such as the distance from the inlet end of the ink jet head, the curvature of the inner surface at the end of the supply path 10, the direction of gravity when the ink jet head 4 is used, the volume of the bubbles 39a, and the depth of the channel 6.

Although the present invention has been described with reference to the illustrated embodiment, other embodiments are possible within the scope of the present invention. For example, the configuration described with reference to FIG. 7 is not indispensable, and may not be adopted unless an advantage of such a configuration is expected. Therefore, the present invention can be applied to the case where the deepest part 40 in the supply path 16 is located at the position where the center line 41 of the channel 6 passes as shown in FIG. 10 or the imaginary line in FIG. Can be.

In the illustrated embodiment, the actuator 6 has the channels 6 in two rows.
It may have more than one row, or just one row. Further, in the above description, the actuator 7 is of a type that ejects ink using deformation when an electric field is applied to the piezoelectric ceramic, but instead, for example, an actuator using a heating element is used. And so on.

[0038]

As described above, according to the first aspect of the present invention, the width of the end portion of the supply path is narrower toward the final end, so that the bubbles remaining there are reduced. , Can be brought very close to the entrance end of any channel near the final end, and therefore
If the purge is performed at the time of the initial introduction of the ink, the bubbles remaining near the final end can be easily and effectively removed through any of the channels near the final end. Therefore, after the initial introduction of the ink, and further, for example, when the ink jet head is left unused and is going to be used, bubbles remaining near the last end of the supply path cause the final end of the supply path. It is possible to prevent non-ejection of ink from occurring in a channel communicating with the vicinity, and it is possible to improve the reliability of the print quality of the ink jet head when ink is initially introduced.

Next, according to the invention as set forth in claim 2, first, the following effects are obtained. That is, since the supply path in the manifold is located at the deepest position at a position shifted from the position where the center line of the channel on the actuator side passes, it is compared with the case where the deepest portion is located at the position where the center line of the channel passes. Thus, the distance between the deepest part and the inlet end of the channel can be increased, while keeping the cross-sectional area of the supply channel substantially the same or not too large, and therefore located at the deepest part Even if the bubble growth proceeds at a similar rate, the time it takes for the outer surface of the bubble to reach the inlet end of the channel can be longer.
For this reason, it is possible to prevent bubbles from being drawn into the channel for a relatively long period of time, so that a good printing state can be maintained for a long time. Further, the frequency of the necessary purge can be reduced, and the burden on the maintenance system including the purge device can be reduced. Further, since the amount of ink wasted by purging can be reduced, the amount of ink that can be used for the original printing can be increased.

However, as a reverse of the advantageous effect as described above, if only the technical matter described in claim 2 is simply adopted, undesirably, the deepest part near the final end of the supply path is undesirably formed. Residual air bubbles are kept away from the inlet end of the channel, which may result in more difficult purging of the air bubbles. However, since the technical matter described in claim 2 is applied to the invention described in claim 1, the width of the terminal end of the supply path is gradually reduced as described in claim 1. Thus, the bubbles located near the final end of the supply path can be brought closer to the inlet end of the channel, and the bubbles can be easily removed by purging.

According to the third aspect of the present invention, since the bubbles remaining in the supply path tend to be located at the deepest part, the deepest part at the end of the supply path is defined as the final end of the supply path. By moving closer to the position where the center line of the channel passes, the air bubbles located at the deepest position can be reliably removed by purging.

The invention described in claim 4 is applied to the invention described in any one of claims 1 to 3,
As described in claim 4, a plurality of channels are formed in a plurality of rows and are respectively aligned in each row,
Further, when the supply path is formed along each row of the plurality of channels, the cross-sectional area of the supply path cannot be so large, so that the purge load can be reduced. In this case, bubbles cannot be retained for a long time. Therefore, it is important that bubbles remaining near the final end can be effectively removed as described in claim 1.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing the entirety of an ink jet recording apparatus 1 incorporating an ink jet head according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a main part of the printing mechanism 2 shown in FIG.

FIG. 3 is a perspective view showing the inkjet head 4 shown in FIG. 2 alone;

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is a sectional view taken along line VV in FIG. 3;

FIG. 6 is a diagram showing the inkjet head 4 with a cross section along the line VI-VI in FIG. 2;

FIG. 7 is an enlarged view of a portion VII in FIG. 5;

8 is an enlarged view of a portion VIII of FIG. 6, showing a part of a joint surface of the actuator 7 to the manifold 8. FIG.

9 is a view showing the vicinity of the last end of the supply path 16 with a cross section along the line IX-IX in FIG.

10 is an enlarged view of an inlet end of a channel 6 on an actuator 7 side and a supply path 16 on a manifold 8 side, which are provided in an ink jet head of interest to the present invention, corresponding to FIG.

11 is a diagram corresponding to FIG. 8 in the ink jet head of FIG. 10;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink-jet recording device 2 Printing mechanism 3 Purge device 4 Ink-jet head 5 Ink cartridge 6 Channel 7 Actuator 8 Manifold 9 Nozzle 16 Supply path 39, 39a Bubbles 40 Deepest part 41 Center line

Claims (4)

[Claims] 1. An actuator in which a plurality of channels for accommodating ink are formed in an aligned state, and the actuator is driven to eject ink in the channels as droplets from nozzles, and the actuator at an inlet end of the channel. And a supply path extending in the direction in which the plurality of channels are aligned and commonly opening to each of the inlet ends of the channels, for supplying ink to each of the channels. , A manifold,
In the ink jet head, the width of the terminal end of the supply path is narrower toward the final end. 2. The ink jet head according to claim 1, wherein the supply path has a deepest portion located at a position shifted from a position where a center line of the channel passes. 3. A terminal portion of the supply passage, wherein the deepest portion extends closer to a position where the center line of the channel passes as it goes to a final end of the supply passage. The inkjet head according to claim 2. 4. The method according to claim 1, wherein the plurality of channels are formed in a plurality of rows and are aligned in each row, and the supply paths are formed along each row of the plurality of channels. The inkjet head according to any one of claims 1 to 3.