JP3552024B2 - Ink jet recording head - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet recording head that presses ink in a pressure generating chamber that communicates with a nozzle opening and a reservoir by a pressure generating unit to discharge ink droplets from the nozzle opening.
[0002]
[Prior art]
The ink jet recording head seals a pressure generating chamber communicating with a reservoir, a nozzle opening, and a flow path substrate in which an ink supply port is formed by a lid, and seals the pressure generating chamber with a heating element or a pressure generating chamber. The pressure is applied by a pressure generating means such as a piezoelectric vibrator provided so that the portion can be deformed, and an ink droplet is ejected from a nozzle opening.
However, when one pressure generating chamber is pressurized by the pressurizing means to discharge ink droplets, a part of the ink flows backward from each ink supply port to the reservoir, and the pressure of the ink supply ports of the other pressure generation chambers fluctuates. As a result, crosstalk is generated, and the ejection performance of ink droplets is affected.
Therefore, in order to absorb the pressure fluctuation caused by the ink flowing back into the reservoir, an elastic deformation region displaceable by the pressure fluctuation is formed in the entire reservoir and absorbed in the elastic region.
[0003]
On the other hand, if the number of nozzle openings in one row increases to realize high-speed printing, it becomes difficult to eliminate air bubbles that have stagnated in the end region of the reservoir. The end area C of the reservoir B that supplies the ink is tapered, and a negative pressure is applied to the nozzle opening to increase the ink flow velocity in the end area at the time of forcibly discharging the ink, thereby improving the elimination of bubbles. Has been done.
[0004]
[Problems to be solved by the invention]
However, since the deformation region of the elastic plate that seals the end region C of the reservoir B becomes narrow, compliance in the end region C cannot be sufficiently ensured, and there is a disadvantage that crosstalk is likely to occur. .
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent ink droplet ejection failure due to bubbles remaining in an end region of a reservoir while ensuring compliance in the end region. It is an object of the present invention to provide an ink jet recording head capable of preventing the occurrence of crosstalk by securing the recording quality.
[0005]
[Means for Solving the Problems]
In order to solve such a problem, the present invention includes a plurality of pressure generating chambers that receive ink supply from a reservoir through an ink supply port, and are pressurized by pressurizing means to discharge ink droplets from a nozzle opening. In an ink jet recording head including a flow path unit provided with an elastically deformable region for absorbing pressure after ejecting ink droplets on one surface of the reservoir, the reservoir is formed as a substantially rectangular opening, An end region distant from the ink introduction port for receiving the ink supply is extended outside the ink supply port , and the end region is formed as a concave portion that opens to the elastic deformation region side .
[0006]
[Action]
Air bubbles that are likely to stagnate at the end of the reservoir are kept in an end area away from the ink supply port to prevent the bubbles from flowing into the pressure generating chamber during printing, and that a sufficient amount is provided outside the outermost ink supply port. Compliance can be given to prevent crosstalk.
Further, since the end region is formed as a concave portion that opens to the elastic deformation region side and has a small cross-sectional area, air bubbles stagnating in the end region can be moved to the ink supply port side and easily discharged. Can be.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Therefore, the details of the present invention will be described below based on the illustrated embodiment.
FIG. 1 shows an embodiment of the present invention, in which a piezoelectric vibrator 1 which expands and contracts in an axial direction which constitutes a pressure generating means has its tip abutting on an elastic plate 3 which constitutes a flow path unit 2. In this state, it is fixed to the head holder 4. The flow channel unit 2 is configured by laminating an elastic plate 3, a flow channel forming substrate 5, and a nozzle plate 7 having a nozzle opening 6.
[0008]
The flow path forming substrate 5 includes a reservoir 8 formed as a through hole, first and second pressure generating chambers 9 and 10 including concave portions formed on the piezoelectric vibrator 1 side and the nozzle plate 7 side, and a first pressure generating chamber. Nozzle communication comprising a first ink supply port 11 formed as a recess communicating with the generation chamber 9, a second ink supply port 12 communicating with the second pressure generation chamber 10, and a through hole at a position facing the nozzle opening 6. The hole 13 is formed.
[0009]
The elastic plate 3 is an island that transmits a displacement of the piezoelectric vibrator 1 by etching or the like by laminating a laminate of an elastically deformable film 3a having ink resistance such as a polymer and a highly rigid material 3b such as a metal. It comprises a diaphragm portion 15 for changing the volume of the pressure generating chamber 9 by the displacement of the portion 14, the island portion 14, and a compliance imparting portion 16 for absorbing pressure fluctuations of the reservoir 8.
[0010]
FIG. 2 shows an embodiment of the above-mentioned flow path forming substrate 5, in which the reservoir 3 is formed in a substantially rectangular shape so as to have substantially the same width for all the pressure generating chambers 9, 10. An ink inlet 17 through which ink from the outside flows is formed at the center of each reservoir 3.
[0011]
The pressure generating chambers 9 ′, 10 ′ at the ends are formed so as to be located at a fixed distance L from the ends of the reservoirs 8, 8, for example, several times the width of the pressure generating chambers 9, 10. .
[0012]
In the case where a silicon single crystal substrate is used for such a flow path forming substrate 3, the (110) plane is anisotropically full-etched or anisotropically half-etched in accordance with the through-holes and recesses. When other materials that can be manufactured and that can be etched, such as glass and metal, are used, a region where a through hole is to be formed is fully etched by an etching method suitable for each material, and a concave portion is formed. The region to be formed can be easily manufactured by performing half etching.
[0013]
In this embodiment, when the piezoelectric vibrator 1 contracts and the first pressure generating chambers 9 and 9 'expand, ink in the reservoir 8 is supplied from the first ink supply ports 11 and 11' to the first pressure generating chambers 9 and 9 '. And flows from the second ink supply ports 12, 12 'into the second pressure generating chambers 10, 10'.
[0014]
At this time, since the bubbles B, B remaining at the end of the reservoir and the ink supply ports 11 ', 12' of the pressure generating chambers 9 ', 10' at the ends are separated from each other, the flow velocity is about the same as the ink droplet ejection. In F1, the ink cannot flow into the pressure generating chambers 9 'and 10', and does not affect the ejection of the ink droplets.
[0015]
When the piezoelectric vibrator 1 is extended and the elastic plate 3 is pressed toward the nozzle plate at the stage when the filling of the pressure generating chambers 9 and 9 ′ with ink is completed, the ink in the first pressure generating chambers 9 and 9 ′ is pressed. Part of the ink flows into the second pressure generating chambers 10 and 10 ′ through the nozzle communication holes 13 and is discharged as ink droplets from the nozzle openings 6, and the ink supply ports 11 and 11 ′ and the ink supply ports 12 and 12 ', A part of the ink flows back into the reservoir 3.
[0016]
The ink flowing backward from the ink supply ports 11, 11 ', 12, and 12' to the reservoir 8 elastically deforms the elastic plate 3 sealing the reservoir 8 by its own pressure, and the pressure quickly decreases. In this embodiment, the reservoir 8 is formed in a rectangular shape, and the elastic plate 3 exists outside the ink supply ports 11 'and 12' located at the ends. The deformation area of No. 3 is sufficiently ensured, and the ink flowing from the ink supply ports 11 'and 12' at the ends is easily absorbed, and crosstalk in the end areas is prevented.
[0017]
By the way, when air bubbles enter the reservoir 8 due to long-time printing or replacement of the ink cartridge, the recording head is sealed by capping means, and the negative pressure of the suction pump is applied to the nozzle opening 6 to discharge the ink. When the ink is forcibly discharged, the bubbles B, B flow into the ink supply port 11 'due to the fast ink flow F2 and are discharged to the outside.
[0018]
In order to easily remove air bubbles stagnating in the end region of the reservoir 8 as described above, as shown in FIGS. 4 and 5, an oblique position is formed in the end region of the reservoir 8 where the ink supply port is not formed. It is desirable that the walls 8a and 8b be formed to have a tapered shape.
[0019]
According to this embodiment, when the ink is forcibly ejected by applying a negative pressure from the outside, the end region of the reservoir 8 is narrowed. It can be easily discharged from the pressure generating chambers 9 and 10 by drawing to the supply port sides 11 'and 12'. Of course, since the reservoir 8 is extended to the outside of the pressure generating chambers 9 'and 10' at the ends, the compliance of the end region can be sufficiently ensured and the occurrence of crosstalk can be prevented.
[0020]
When the tapered portion 8c is formed as smoothly as possible as shown in FIG. 6, the stagnation of the ink at the corners can be reduced, and the discharge of air bubbles can be further enhanced.
[0021]
FIG. 7 shows another embodiment of the present invention, in which an end region of the reservoir 8 is provided with a step 8d which can secure a gap at least not to lower the compliance of the elastic plate. The recess 8e is formed by half etching or the like.
[0022]
According to this embodiment, when the ink flows backward from the ink supply port 11 after the ejection of the ink droplet, the elastic plate 3 formed so as to extend further outward than the ink supply port is elastically deformed between the concave portion 8e and the concave portion 8e. Thus, the pressure fluctuation of the reservoir 8 is reliably absorbed.
[0023]
On the other hand, when the ink is forcibly ejected by applying a negative pressure from the outside, the cross-sectional area of the end region of the reservoir 8 is reduced by the concave portion 8e, and the flow velocity of the ink is high. While being guided by the wall 8f of the recess 8e, it moves to the ink supply port 11 ', is sucked into the pressure generating chamber 9', and is discharged to the outside.
[0024]
The wall 8f is preferably formed as a wall 8f 'which is inclined from the wall side to the end side of the reservoir facing the ink supply ports 11, 11' as shown in FIG. When the ink is forcibly discharged, bubbles located on the side of the wall remote from the ink supply port are guided by the oblique wall 8f ', move to the ink supply port 11', and are sucked into the pressure generating chamber. It is easily discharged outside.
[0025]
In the above embodiment, the ink inlet 17 is arranged in the central region of the reservoir 8. However, the ink inlet 21 is arranged at one end of the reservoir 8 as shown in FIG. In this case, the reservoir may be formed to extend only at the end opposite to the inlet port 17.
[0026]
Further, in the above-described embodiment, the recording head using the piezoelectric vibrator in the longitudinal vibration mode as the pressure generating means has been described as an example, but ink is supplied from the reservoir to the plurality of pressure generating chambers, and the nozzle opening is controlled. If the recording head is of the type that removes air bubbles in the reservoir by applying a negative pressure to the pressure, it pressurizes the flexural mode piezoelectric vibrator and the heating element that generates pressure by vaporizing the ink in the pressure generating chamber. Obviously, the present invention can be applied to the ink jet recording head used as the means.
[Brief description of the drawings]
FIG. 1 is a sectional view showing one embodiment of an ink jet recording head of the present invention.
FIG. 2 is a top view showing one embodiment of a flow path forming substrate of the ink jet recording head.
FIG. 3 is an enlarged top view showing an end region of a reservoir of the flow path forming substrate.
FIG. 4 is a top view showing another embodiment of the flow path forming substrate.
FIG. 5 is a top view showing another embodiment of the flow path forming substrate.
FIG. 6 is a top view showing another embodiment of the flow path forming substrate.
FIG. 7 is a perspective view showing, in an enlarged manner, another embodiment of the flow path forming substrate in the vicinity of an ink supply port in a reservoir end region.
FIG. 8 is a perspective view showing, in an enlarged manner, another embodiment of the flow path forming substrate in the vicinity of an ink supply port in a reservoir end region.
FIG. 9 is a top view showing another embodiment of the flow path forming substrate.
FIG. 10 is a top view showing an example of a flow path forming substrate constituting a conventional ink jet recording head.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 piezoelectric vibrator 2 flow path unit 3 elastic plate 5 flow path forming substrate 6 nozzle opening 7 nozzle plate 8 reservoir 9 first pressure generation chamber 10 second pressure generation chamber 11 first ink supply port 12 second ink supply port 13 nozzle Communication hole 16 Diaphragm 17 Ink inlet

Claims (3)

A plurality of pressure generating chambers that receive supply of ink from a reservoir through an ink supply port and are pressurized by a pressurizing unit to discharge ink droplets from a nozzle opening; In an ink jet recording head including a flow path unit provided with an elastic deformation region for absorption,
The reservoir is formed as a substantially rectangular opening, and an end region remote from the ink introduction port that receives supply of ink from the outside is extended outside the ink supply port, and the end region is closer to the elastic deformation region side. An ink jet type recording head formed as a concave portion that opens to the side. The ink jet recording head according to claim 1, wherein an oblique wall for guiding ink toward the ink supply port is formed in the recess. 2. The ink jet recording head according to claim 1, wherein the reservoir is formed as a through hole, and the recess is formed by half etching.

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