JP2001191518A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet head in which no bubble is left between an ink channel and the common ink chamber of a cover plate at the time of initially filling ink and defective print, e.g. missing of dots (print) or bending of print, due to a residual bubble can be prevented. SOLUTION: A step 24a is provided in the vicinity of the outlet of a wide ink channel 24 located in the vicinity of the inlet of an ink supply opening 22 and a filter 30 is fixed using the step 24a. The ink channel 24 has planar shape similar to that of the ink supply opening 22 in a cover plate 17.

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 mounted on an ink jet recording apparatus applied to, for example, a printer and a facsimile.

[0002]

2. Description of the Related Art Conventionally, there has been known an ink jet recording apparatus for recording characters and images on a recording medium by using a recording head for discharging ink from a plurality of nozzles. In such an ink jet recording apparatus, a recording head facing the recording medium is provided on a head holder, and the head holder is mounted on a carriage and scans in a direction orthogonal to a transport direction of the recording medium.

FIG. 1 is an exploded perspective view of an example of such an ink-jet head, FIG.
FIG. 3 shows a cross-sectional front view of an essential part taken along line XX of FIG. 1 to 3
As shown in (1), a plurality of grooves 12 are provided side by side in the width direction of an actuator plate 11 made of piezoelectric ceramic, and each groove 12 is separated by a side wall 13. One end of each groove 12 in the longitudinal direction is the actuator plate 11
, And the other end does not extend to the other end face, but gradually decreases in depth. Electrodes 15 for applying a drive voltage are formed on the opening side surfaces of both side walls 13 and 13 of each groove 12 over the longitudinal direction.

[0004] A cover plate 17 is joined to the opening side of the groove 12 of the actuator plate 11 via an adhesive 19. Each of the grooves 1 is provided on the cover plate 17.
2 has a common ink chamber 21 serving as a concave portion communicating with the other end portion of which is shallow, and an ink supply port 22 penetrating from the bottom of the common ink chamber 21 in a direction opposite to the groove 12. An ink flow path 24 of a flow path block 23 communicates with and opens to the ink supply port 22.

[0005] On the end face of the joint body between the actuator plate 11 and the cover plate 17 where the groove 12 is open,
The nozzle plate 25 is attached and bonded with an adhesive, and a nozzle opening 27 is formed at a position of the nozzle plate 25 facing each of the grooves 12. A wiring board 36 is fixed to a surface of the actuator plate 11 opposite to the nozzle plate 25 and opposite to the cover plate 17. Each of the electrodes 15 is provided on the wiring board 36.
A wiring 38 connected to the electrode 15 by a bonding wire 37 or the like is formed, and a driving voltage can be applied to the electrode 15 via the wiring 38.

In the recording head configured as described above,
From the ink flow path 24 to the ink supply port 22, the common ink chamber 2
1 is filled with ink into each groove 12 through a predetermined groove 12.
When a predetermined driving voltage is applied to the side walls 13 on both sides of the first through the electrodes 15, the side walls 13 are deformed and the volume in the predetermined grooves 12 is changed. Discharged.

For example, as shown in FIG. 4 which is a front sectional view of a main part, when ink is ejected from the nozzle opening 27 corresponding to the groove 12a, the electrodes 15a, 15 in the groove 12a are discharged.
A positive drive voltage is applied to the electrode b, and the opposing electrodes 15c and 15d are grounded. As a result, a driving electric field acts on the side walls 13a and 13b in a direction toward the groove 12a. If this is perpendicular to the polarization direction of the actuator plate 11 made of piezoelectric ceramic, the side walls 13a and 13b are moved in the direction of the groove 12 by the piezoelectric thickness-shear effect. Warp, the volume in the groove 12 decreases, the pressure increases,
Ink is ejected from the nozzle openings 27.

Conventionally, the flow path block 2 communicating with and opening to the ink supply port 22 of the cover plate 17 has been described.
As shown in FIG. 8, which is a front sectional view of the ink jet head, a filter 40 for filtering foreign matter in the ink in the ink flow path 24 of the third embodiment has a narrow opening near the ink inlet 31 for taking in ink from outside the flow path. 32 is provided with a step portion 32a, and a filter 40 having a relatively small area is provided in the step portion 32a.
I was wearing.

[0009]

By the way, when the ink jet recording apparatus is first used, when the recording head is exchanged, and when the ink cartridge is exchanged, etc., the printing medium of the nozzle plate 25 is opposed. A suction cap (not shown) of a vacuum suction device (not shown) is brought into close contact with the surface on the side to be cleaned, and ink is passed through the ink inlet 31 and the filter 40 from the ink cartridge (not shown) through a tube (not shown) from the ink cartridge (not shown) while performing vacuum suction. While the recording head was initially filled with ink.

However, in the recording head having the above-described configuration, the shape of the ink flow path 24 is different from that of the filter 4.
After passing through 0, the width of the common ink chamber 21 over the substantially entire width of the cover plate 17 rapidly increases so as to extend over substantially the entire width of the ink supply port 22 penetrating in a direction opposite to the groove 12. For this reason, the ink that has passed through the filter 40 is scattered in a wide cross-sectional area in the ink flow path 24 like a shower while the air is entrained, and the cover plate 17
Even if ink flows into the inside of the actuator plate 11 and the inside of the actuator plate 11, bubbles 41 remain between the filter 40 of the ink flow path 24 and the common ink chamber 21 of the cover plate 17.

The ink flow path 24 of the flow path block 23
And the planar shape of the ink supply port 22 provided on the upper part of the cover plate 17 are significantly different. In particular, when the latter is larger than the former, it is difficult for the ink to flow into the shoulder formed at the joint between the two. As a result, air bubbles are generated and air bubbles 4
1 remains. The remaining bubbles 41 are
Since the pumping action of the groove 12 due to the application of voltage to the electrode 15 of the groove 12 of the actuator plate 11 is impeded, ink is not ejected from the nozzle opening 27 of the nozzle plate 25, causing dot missing (printing missing) or nozzle opening. Ink is bent and ejected from 27 to cause printing failure.

In view of the above-mentioned problems, the present invention does not allow air bubbles to remain between the ink flow path and the common ink chamber of the cover plate at the time of initial filling of ink. It is an object of the present invention to provide an ink jet head capable of preventing the occurrence of printing defects such as print omission and print bending.

[0013]

According to a first aspect of the present invention, there is provided an actuator plate made of a piezoelectric ceramic having a plurality of grooves formed on one side and one end, and an actuator plate formed of the piezoelectric ceramic. A common ink chamber joined to one surface and sealing a part of the opening of the groove and an ink supply port penetrating from the bottom of the common ink chamber in a direction opposite to the groove were formed. A cover plate, a flow path block having a wide ink flow path in which an input side communicates with a narrow opening near the ink inlet and an output side communicates with the ink supply port, and sealing the one end surface of the actuator plate; A nozzle plate having a nozzle opening corresponding to each of the grooves; and applying a drive voltage to electrodes provided on side walls in the grooves. An ink jet head that changes the volume in the groove and discharges the ink filled therein from the nozzle opening, wherein a filter is provided near an outlet of the wide ink flow path close to an inlet of the ink supply port. An inkjet head characterized by being mounted.

According to a second aspect of the present invention, in the first aspect, the planar shape of the ink flow path is similar to the planar shape of the ink supply port of the cover plate. Head. Third of the present invention
The aspect of the present invention is the ink jet head according to the second aspect, wherein the planar shape of the ink flow path is formed larger than the planar shape of the ink supply port of the cover plate.

According to a fourth aspect of the present invention, in the first aspect, the planar shape of the ink supply port of the cover plate is approximated to the planar shape of the wide ink flow path of the flow path block. Is an ink jet head. According to a fifth aspect of the present invention, in the fourth aspect,
An ink jet head, wherein the planar shape of the ink supply port of the cover plate is formed smaller than the planar shape of the wide ink flow path of the flow path block. (Function) With the above-described configuration, the ink flowing from the ink inlet of the flow path block flows through a narrow opening near the ink inlet and a wide ink flow path on the upstream side of the filter. It spreads to a planar shape approximating the supply port and then passes uniformly through the filter. As a result, the ink does not flow from a narrow opening near the ink inlet through a part of the filter near the ink, resulting in a short-circuit and rapid flow, and the other ink has a narrow opening near the ink inlet. Part, and spreads to both sides with lower flow resistance. By this phenomenon, the ink is uniformly filled in the wide ink flow path, in other words, the entire wide ink storing section, and the bubbles in the ink flow path at the time of the initial ink filling are prevented from remaining.

In addition, the ink uniformly filled in the wide ink flow path, in other words, the entire wide ink reservoir, is filtered by a filter and then flows into an ink supply port having a substantially similar planar shape, and the cross-sectional area of the flow is sharp. As in the case of the conventional inkjet head, the ink that has passed through the filter does not become entangled with air as in the case of the conventional inkjet head, and does not scatter to the ink supply port as in a shower. Air bubbles in the ink supply port are prevented from remaining.

Further, the planar shape of the ink flow path and the planar shape of the ink supply port are approximated, and the planar shape of the ink flow path is formed larger than the planar shape of the ink supply in the approximate planar shape. Alternatively, by forming the planar shape of the ink supply port smaller than the planar shape of the ink flow path, the residual air bubbles are trapped at the shoulder of the wide ink flow path, and air bubbles are generated between the filter and the common ink chamber of the cover plate. Prevent the inflow of water.

As a result, it is possible to eliminate ink discharge defects such as missing dots and print bending due to residual bubbles, and to realize stable discharge.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited thereto. FIG. 1 is an exploded perspective view of a main part of an embodiment of the present invention, FIG. 2 is a side sectional view of the main part of the embodiment, FIG.
FIG. 4 is a front sectional view of a main part taken along the line XX of FIG. 2, and FIG. 4 is a front sectional view of a main part for explaining the driving principle of the ink jet head of the present embodiment.

The structure and the driving principle of the ink jet head shown in FIGS. 1 to 4 are the same as the structure and the driving principle of the conventional ink jet head described above with reference to FIG. FIG. 5 is a front sectional view taken along the line YY of FIG. 2 showing an embodiment of the present invention according to any one of claims 1, 2 and 4.

As shown in FIG. 5, in the embodiment of the present invention, a step 24a is provided near the outlet of the wide ink flow path 24 near the inlet of the ink supply port 22.
And the filter 30 is mounted using the step 24a. In the embodiment of the present invention according to claim 2 or 4, as shown in FIG. 5, the planar shape of the ink flow path 24 is a planar shape similar to the ink supply port 22 of the cover plate 17. .

Incidentally, the aperture of the filter 30 is such that when the inner diameter of the nozzle opening 27 is, for example, 25 μm,
The size may be smaller than this, for example, 20 μm.
With the above configuration, the ink flowing from the ink inlet 31 of the flow path block 23 flows through the narrow opening 32 near the ink inlet 31 to the wide ink flow path 24 on the upstream side of the filter 30 to flow through the filter 30. It spreads to a planar shape approximate to the ink supply port 22 due to the path resistance, and then passes through the filter 30 uniformly. Therefore, the ink does not flow from the narrow opening portion 32 near the ink inlet 31 through a part of the filter 30 close to the ink inlet 31 to form a short-circuit fast flow, and the other ink does not flow. It spreads away from the nearby narrow opening 32 and to both sides having lower flow path resistance. By this phenomenon, the ink is uniformly filled in the wide ink flow path 24, in other words, the entire wide ink storage section 24, and the bubbles 41 in the ink flow path 24 at the time of the initial ink filling are prevented from remaining.

The ink uniformly filled in the wide ink flow path 24, in other words, the entire wide ink storing section 24, is filtered by the filter 30 and then flows into the ink supply port 22 having a substantially similar planar shape, and the flow of the ink is changed. Since the cross-sectional area does not suddenly increase, the ink that has passed through the filter 30 as in the case of the conventional inkjet head shown in FIG. This prevents the bubbles 41 from remaining in the ink supply port 22 during the initial filling of the ink.

FIG. 6 is a front sectional view of a principal part taken along the line Y--Y of FIG. 2 showing an embodiment of the present invention according to claim 3 or claim 5. In the embodiment of the present invention according to claim 3 or 5, as shown in FIG.
In the configuration in which the planar shape of the ink supply port 22 is approximated to the planar shape of the ink supply port 22, the planar shape of the ink flow path 24 may be formed larger than the planar shape of the ink supply port 22, The planar shape of the ink supply port 22 is formed smaller than the planar shape of the passage 24.

According to the embodiment of the present invention according to claim 3 or 5 configured as described above, according to claim 1,
The embodiment of the present invention shown in FIG. 5 according to any one of claims 2 and 4 has the same operation and effect as the above operation and effect, and also has the following operation and effect. To play. That is, even if the planar shape of the ink flow path 24 and the planar shape of the ink supply port 22 are formed to be close to each other, the planar shape of the ink flow path 24 is changed as shown in FIG. Forming smaller than the shape,
If the planar shape of the ink supply port 22 is formed larger than the planar shape of the ink flow path 24, the ink flow path 2
4 and a portion where the flow of ink stagnates downstream of the filter 30 at the shoulder of the junction between the ink supply port 22 and
In the ink supply port 22 of the cover plate 17, bubbles 4
1 will remain. According to the above embodiment, such an inconvenient phenomenon can be prevented. Further, even if the flow of the ink is partially uneven due to the bias of the flow path resistance due to the filter 30 in the ink flow path 24,
By forming as in the embodiment shown in FIG. 6, the residual air bubbles 41 are trapped in the shoulder portion in the wide ink flow path 24 (in other words, the wide ink storing portion 24) on the upstream side of the filter, and the cover is removed from the filter. The bubbles 41 can be prevented from flowing into the common ink chamber of the plate 17.

[0026]

The present invention has the following excellent effects. (1) According to the present invention according to any one of the first, second, and fourth aspects, with the above-described configuration, the ink flowing from the ink inlet of the flow path block is supplied to the ink inlet. The ink spreads in a wide ink flow path upstream of the filter from a nearby narrow opening to a planar shape approximate to the ink supply port due to the flow path resistance of the filter, and then passes through the filter uniformly. As a result, the ink does not flow from a narrow opening near the ink inlet through a part of the filter near the ink, resulting in a short-circuit and rapid flow, and the other ink has a narrow opening near the ink inlet. Part, and spreads to both sides with lower flow resistance. By this phenomenon, the ink is uniformly filled in the wide ink flow path, in other words, the entire wide ink storing section, and the bubbles in the ink flow path at the time of the initial ink filling are prevented from remaining.

In addition, the ink which is uniformly filled in the wide ink flow path, in other words, the entire ink storage portion, is filtered by a filter and then flows into an ink supply port having a substantially similar planar shape, and the cross-sectional area of the flow sharply increases. As in the case of the conventional inkjet head, the ink that has passed through the filter does not become entangled with air as in the case of the conventional inkjet head, and does not scatter to the ink supply port as in a shower. Air bubbles from the ink flow path to the common ink chamber are prevented from remaining. As a result, missing dots (missing printing) and poor printing are eliminated. (2) According to the third or fifth aspect of the present invention, the planar shape of the ink flow path and the planar shape of the ink supply port are formed by approximating the planar shape of the ink flow path. By forming the shape larger than the plane shape of the ink supply or by forming the plane shape of the ink supply port smaller than the plane shape of the ink flow path, in addition to the same effect as the above item (1), a wide ink flow Residual air bubbles are trapped at the shoulder of the road, so that air bubbles can be prevented from flowing from the filter to the common ink chamber of the cover plate.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main part of an embodiment of an ink jet head according to the present invention.

FIG. 2 is a side sectional view of a main part of the embodiment.

FIG. 3 is a front sectional view of a main part taken along line XX of FIG. 2;

FIG. 4 is a main part front sectional view for explaining the driving principle of the ink jet head of the embodiment.

FIG. 5 is one of claims 1, 2 and 4;
FIG. 3 is a front sectional view taken along line YY of FIG. 2 according to the embodiment of the present invention.

FIG. 6 is a front sectional view taken along the line YY in FIG. 2 of the embodiment of the present invention according to claim 3 or 5;

FIG. 7 is a front sectional view taken along the line YY of FIG. 2 for explaining the operation of the embodiment of the present invention according to claim 3 or 5;

FIG. 8 is a front sectional view taken along line YY of FIG. 2 showing an example of a conventional inkjet head.

[Explanation of symbols]

 Reference Signs List 11 actuator plate 12, 12a groove 13, 13a, 13b side wall 15 electrode 15a to 15d electrode 17 cover plate 19 adhesive 21 common ink chamber 22 ink supply port 23 flow path block 24 ink flow path 24a step 25 nozzle plate 27 nozzle opening 30 Filter 31 Ink inlet 32 Opening 32a Step 36 Wiring board 37 Bonding wire 38 Wiring 40 Filter 41 Bubble

Claims (5)

[Claims] 1. An actuator plate made of piezoelectric ceramic having a plurality of grooves formed on one side and one end, and a part of the opening of the groove is sealed while being joined to the one side of the actuator plate. A cover plate in which a common ink chamber communicating with the groove and an ink supply port penetrating from the bottom of the common ink chamber in a direction opposite to the groove are formed, and the inlet side is connected to a narrow opening near the ink inlet and out. A channel block provided with a wide ink channel having a side communicating with the ink supply port; and a nozzle plate sealing the one end surface of the actuator plate and having a nozzle opening corresponding to each of the grooves. By applying a driving voltage to the electrodes provided on the side walls in the groove, the volume in the groove is changed to fill the inside of the groove. An ink jet head that discharges ink from the nozzle opening, wherein a filter is mounted near an outlet of the wide ink flow path close to an inlet of the ink supply port. 2. The ink jet head according to claim 1, wherein the planar shape of the ink flow path is similar to the planar shape of the ink supply port of the cover plate. 3. The ink jet head according to claim 2, wherein the planar shape of the ink flow path is formed larger than the planar shape of the ink supply port of the cover plate. 4. The ink jet head according to claim 1, wherein the planar shape of the ink supply port of the cover plate is approximated to the planar shape of a wide ink flow path of the flow path block. 5. The ink jet head according to claim 4, wherein the planar shape of the ink supply port of the cover plate is formed smaller than the planar shape of the wide ink flow path of the flow path block.