JP3221405B2 - Inkjet recording head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-nozzle type ink jet recording head using a piezoelectric material.

[0002]

2. Description of the Related Art FIG. 15 shows an example of an ink jet recording head in a conventional ink jet recording apparatus.
The concave portion 52 is formed on one surface of the piezoelectric plate 51, the convex portion 53 is protruded from the bottom surface of the concave portion 52, and the cover plate 54 is attached to one surface of the piezoelectric plate 51. A configuration in which 52 is an ink chamber is known (see U.S. Pat. No. 4,819,014). In this ink jet recording head, electrodes 55 and 56 are provided on the other surface of the piezoelectric plate 51 and the tip surface of the convex portion 53, and a voltage is applied between the electrodes 55 and 56 so that the convex portion of the piezoelectric plate 51 is formed. The ink is ejected from the nozzle holes 57 by deforming the nozzle 53 in the thickness vibration mode, that is, the mode of the vertical vibration in FIG.

[0003]

However, in the configuration of FIG. 15, since the thickness vibration mode is used, the projection 53
It is necessary to secure a certain height or more of the convex portion 53 in order to obtain a sufficient volume change, and since the distance h between the electrodes 55 and 56 is large, for example, about 500 μm, it is necessary to apply a considerably high voltage. As a result, the cost of a driver device for applying a voltage between the electrodes 55 and 56 is high, and the manufacturing cost of the entire inkjet recording device is high.

The present invention has been made in view of the above circumstances, and has as its object to provide an ink jet recording head which can reduce the manufacturing cost of the entire ink jet recording apparatus.

[0005]

Means for Solving the Problems] To achieve the above object, the present invention is partitioned by a wall made of non-piezoelectric material
A plurality of ink chambers and nozzles corresponding to these ink chambers, and ejects ink droplets from the corresponding nozzles according to a change in the volume of the ink chambers. A plurality of piezoelectric active portions having elongated electrodes extending in the direction, a member provided so that a specific surface extending in each longitudinal direction is opposed to each of the ink chambers, each piezoelectric active portion, The direction of polarization is the same as the direction of the electric field formed by the input signal from the corresponding electrode, the direction of expansion and contraction is the longitudinal direction, and the direction perpendicular to the longitudinal direction of the specific surface caused by the expansion and contraction in the longitudinal direction. The volume of the ink chamber may be changed by the deformation (claim 1). Here, the member may be a plate-shaped piezoelectric material having a plurality of grooves formed on a surface thereof, and the plurality of elongated protrusions formed between the grooves may be formed of the plurality of piezoelectric active members. (Claim 2).

Further, according to the present invention, each of the convex piezoelectric active portions is polarized in a direction from one side surface to the other side surface in the longitudinal direction, and long electrodes are provided on both side surfaces thereof. It is formed (claim 3).

[0007]

According to the first aspect of the present invention, each piezoelectric active portion has a long electrode extending in parallel with the longitudinal direction of the ink chamber and a specific surface extending in the same direction as the longitudinal direction. And this surface faces the ink chamber. Each piezoelectric active portion expands and contracts in the longitudinal direction in response to an input signal from the electrode. Then, the deformation of the specific surface in the direction orthogonal to the longitudinal direction caused by the expansion and contraction in the longitudinal direction causes a change in the volume of the ink chamber.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. The ink jet recording apparatus includes a main body feeding drive system 1, a main engine controller 2, a controller 3, a cleaning / recovery mechanism 4, An interface 5, a driver unit 6, a line head unit 7, an operation unit 8, a paper discharge tray 9, a body 10, a recording paper cassette 11, and an ink supply cartridge 12 are provided.
Has a multi-nozzle head 13 for four colors of yellow, magenta, cyan and black.

FIG. 2 is a plan view of the multi-nozzle head 13, for example, on a base plate 15 made of glass.
A terminal plate 16 made of, for example, glass and a piezoelectric body 17 made of, for example, piezoelectric ceramics are provided, and a support member 18 made of, for example, glass is provided on the piezoelectric body 17. A nozzle plate 19 made of, for example, a polyimide film is installed on the front surface of the piezoelectric body 17 and the support member 18, and an ink lid 20 made of, for example, glass is installed on the support member 18. A closing plate 21 made of, for example, glass is provided on both side surfaces of the piezoelectric body 17 and the supporting member 18. A large number of terminals 22 and a large number of conductors 23 connected to each terminal 22 are integrally formed on the terminal plate 16 by, for example, metal evaporation. Ink lid 2
For example, two holes 24 for supplying ink composed of, for example, a pigment-dispersed oil-based ink are formed at 0.

FIG. 3 is a perspective view of a main part of the multi-nozzle head 13, FIG. 4 is a cross-sectional view of the main part of the multi-nozzle head 13 along the width direction, and FIG. In the cross-sectional view, a number of convex portions 26 along the depth direction are formed at predetermined intervals in the width direction except for the rear end portion of the piezoelectric body 17, and each convex portion 26 is a concave portion formed on the support member 18. 27. The piezoelectric body 17 and the support member 18 are fixed to each other by, for example, an epoxy-based adhesive 28, and a gap that forms an ink chamber 29 is formed between the tip surface of the convex portion 26 and the bottom surface of the concave portion 27. I have. Piezoelectric body 17, support member 18, and nozzle plate 1
9 are fixed to each other by, for example, an epoxy adhesive 30, and the nozzle plate 19 is formed with a large number of tapered nozzle holes 31 communicating with the ink chamber 29. An electrode 32 is provided on one side surface of each projection 26 of the piezoelectric body 17.
Is provided, and an electrode 33 is provided on the other side surface. That is, the polarization direction of the piezoelectric body 17 and the electrode 32,
The direction of the electric field formed between the electrodes 33 is parallel to each other, and the parallel direction intersects with the ink ejection direction. The electrodes 32, 33 wrap around the front end surface at the rear end of the convex portion 26, and are connected to the driver unit 6 via the conductor 34 and the conductor 23 and the terminal 22 of the terminal plate 16 (FIG. 2).
(FIG. 1). The support member 18 has an ink supply slit 35 communicating with all the ink chambers 29.
The ink supply slit 35 is covered by the ink lid 20 (FIG. 2) and the closing plate 21 (FIG. 2). The rear end of the piezoelectric body 17 is flush with the front end surface of the projection 26.

As the nozzle plate 19, for example, a polyimide film (Toray: Kapton) having a thickness of about 25 to 200 μm can be used, and the diameter of the nozzle hole 31 is, for example, about 20 to 100 μm. Support member 18
Is, for example, about 5 to 20 mm, and the width of the projection 26 is, for example, about 30 to 130 μm. Also, the convex portion 26
Is, for example, 62.5 to 250 μm (pixel density: 4
00 to 100 dpi).

FIG. 6 is an explanatory view of a manufacturing process of a main part of the multi-nozzle head 13. In manufacturing the multi-nozzle head 13, first, as shown in FIG. A resist 37 is applied. Next, FIG.
As shown in (B), a large number of grooves are cut on the surface side of the piezoelectric body 17 with a dicing saw to form the convex portions 26. Next, FIG.
As shown in (C), a metal film 38 is formed on the projection 26 by oblique evaporation. Thus, the resist 37 is covered with the metal film 38. Next, as shown in FIG. 6D, the resist 37 is removed by etching to form the electrodes 32 and 33 while leaving the metal film 38 only on both side surfaces of the convex portion 26. At this time, although the resist 37 is covered with the metal film 38, the resist 37 can be peeled off when the etchant enters the front and back sides of the paper surface of FIG. Next, as shown in FIG. 6E, the piezoelectric member 17 is attached to the support member 18 to which the adhesive 28 is applied.
And the convex portion 26 of the piezoelectric body 17 is fitted into the concave portion 27 of the support member 18. Next, the adhesive 28 is hardened by baking as shown in FIG. Thereafter, a polyimide film is applied to the front surface of the piezoelectric body 17 and the support member 18 with an adhesive 30.
(FIG. 5) to form the nozzle plate 19 (FIG. 5), and the nozzle holes 31 (FIG. 5) by excimer laser.
To form

Next, the operation will be described. When a pulse voltage is applied between the electrodes 32 and 33 by the driver unit 6 according to the image signal, an electric field is formed between the electrodes 32 and 33 as shown by an arrow A in FIG. At this time, since the piezoelectric body 17 is polarized in the direction of the arrow B, the convex portion 26 of the piezoelectric body 17 is deformed in the long-side direction elastic vibration mode, that is, the mode in which the convex portion 26 expands and contracts and vibrates in the longitudinal direction. . Due to the expansion and contraction and vibration in the longitudinal direction, the convex portion 26 is in a state like a virtual line in a direction orthogonal to the longitudinal direction. Therefore, the volume of the ink chamber 29 between the front end surface of the convex portion 26 and the bottom surface of the concave portion 27 is reduced, and the ink in the ink chamber 29 is pressurized, the ink is ejected from the nozzle hole 31 and recording paper (not shown) is formed. ). At this time, the side surface of the convex portion 26 has a concave shape like an imaginary line. However, since the distance between the side surface of the convex portion 26 and the side wall of the concave portion 27 at the tip of the convex portion 26 is extremely small, the ink The ink in the chamber 29 hardly flows. When the voltage between the electrodes 32 and 33 becomes zero, the convex portion 26 of the piezoelectric body 17 returns to the solid line state, and the volume of the ink chamber 29 increases, so that the ink chamber 29 passes through the ink supply slit 35 of the support member 18. Is supplied with ink. It is preferable that the electrodes 32 and 33 be provided over the protruding length of the protrusion 26 from the tip of the protrusion 26 by 20% or more. If it is less than 20%, the amount of deformation of the convex portion 26 is small, and it is difficult to obtain a pressure sufficient to eject the ink from the nozzle hole 31 in a good manner.

The above operation is sequentially or simultaneously performed for each of the ink chambers 29 in accordance with the image signal, so that an image for one line is drawn, and this is continued in synchronization with the movement of the recording paper. An image corresponding to the image signal is drawn on the recording paper. Thus, the electrodes 3 are provided on both side surfaces of the convex portion 26.
Since the electrodes 2 and 33 are provided, the distance between the electrodes 32 and 33 can be reduced. Further, since the convex portion 26 of the piezoelectric body 17 is deformed in the long-side direction expansion / contraction vibration mode, a region where expansion and contraction is caused by an electric field, that is, an active region is large, and the amount of deformation in a direction orthogonal to the longitudinal direction is effectively reduced. , And as a result, the voltage applied to the electrodes 32 and 33 can be reduced. Therefore, the price of the driver unit 6 can be reduced favorably, and the manufacturing cost of the entire inkjet recording apparatus can be reduced. Further, since it is not necessary to process the piezoelectric body 17 into a complicated cross-sectional shape, the manufacturing cost can be reduced. (Another embodiment) As shown in FIG.
May be provided on the bottom surface of the heater. In this way, the influence of the outside air temperature can be reduced, and a high-viscosity ink can be used.

As shown in FIG. 9, grooves are formed on both side surfaces of the convex portion 26 of the piezoelectric body 17, electrodes 32 and 33 are provided in these grooves, and the side surfaces of the convex portion 26 and the surfaces of the electrodes 32 and 33 are formed. May be flush. As shown in FIGS. 10 to 12,
The piezoelectric member 17 and the support member 18 may be configured to fit together without a gap near the front surface of the multi-nozzle head 13, and a small groove 31 ′ may be formed in the support member 18 to form the nozzle hole 31. Alternatively, a small groove may be formed in the piezoelectric body 17 to form a nozzle hole.

As shown in FIG. 13, the distal end surface of the convex portion 26 of the piezoelectric body 17 and the bottom surface of the concave portion 27 of the support member 18 may be formed as concave surfaces. As shown in FIG.
May be provided from the side surface of the convex portion 26 of the piezoelectric body 17 to the distal end surface, and may be configured in an L-shaped cross section. Such an electrode 3
The electrodes 2 and 33 can be easily formed by depositing a metal from the front end surface of the convex portion 26 to both side surfaces, forming a groove on the front end surface of the convex portion 26 with a dicing saw, and separating the electrodes 32 and 33.

Incidentally, the length of the plurality of ink chambers 29 arranged in parallel may be changed alternately. However, the lengths of the electrodes 32 and 33 are all the same. By doing so, the crosstalk that often occurs when the density of the nozzle holes 31 is increased or the viscosity of the ink is reduced with an increase in temperature, that is, the electrodes 32 and 3 are used.
A phenomenon in which ink is ejected from the nozzle holes 31 of the ink chamber 29 to which no voltage is applied between the three can be satisfactorily prevented.

Further, the electrodes 32 and 33 may be formed so as to gradually increase in width as approaching the nozzle hole 31. By doing so, it is possible to satisfactorily prevent crosstalk and improve the responsiveness of ejecting ink. Further, the adhesive 28 for fixing the piezoelectric body 17 and the support member 18 to each other may be provided only at both ends in the width direction of the multi-nozzle head 13. Even in this case, since the gap between the piezoelectric body 17 and the support member 18 is sufficiently small, the pressure in the ink chamber 29 does not decrease.

In the above embodiment, the ink supply slit 35 is provided in the support member 18 to supply the ink to the ink chamber 29 through the hole 24 of the ink lid 20.
Various configurations for supplying ink to the ink chamber 29 are well known, and a configuration for supplying ink from the side of the closing plate 21 through the ink supply tube 25 can be arbitrarily selected.

[0020]

As described above, according to the ink jet recording head according to the first aspect, each of the piezoelectrically active portions has a long electrode extending in parallel with the longitudinal direction of the ink chamber, and has the same shape as the longitudinal direction. It has a specific surface extending in a parallel direction, and this surface faces the ink chamber. Each piezoelectric active portion expands and contracts in its longitudinal direction in response to an input signal from the electrode. Then, the deformation in the direction perpendicular to the longitudinal direction of the surface caused by the expansion and contraction in the longitudinal direction causes a change in the volume of the ink chamber. That is, since the piezoelectric active portion uses expansion and contraction in the longitudinal direction, a region where expansion and contraction occurs in response to an input signal, that is, an active region can be large, and the expansion and contraction occur even when the input signal has a relatively low voltage. The displacement amount in the direction orthogonal to the longitudinal direction of the specific surface increases, and a sufficient change in the capacity of the ink chamber for forming an ink image can be caused. Therefore, a low-voltage driver device can be applied, and the manufacturing cost of the entire inkjet recording device can be reduced.

Further, according to the ink jet recording head of the second aspect, it is not necessary to process the piezoelectric material into a complicated cross-sectional shape, so that the manufacturing cost can be reduced also in this respect. Further, according to the ink jet recording head according to the third aspect, the convex portion serving as the piezoelectric active portion is polarized in a direction from one side surface to the other side surface in the longitudinal direction, and has a long length on both side surfaces. Since the scale-shaped electrode is formed, the direction of polarization of the piezoelectric material and the direction of the electric field formed between the electrodes are parallel to each other, and can be efficiently expanded and contracted in the longitudinal direction. The amount of deformation in the direction perpendicular to the direction can be increased, and ink can be efficiently ejected from the nozzles.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of the multi-nozzle head.

FIG. 3 is a perspective view of a main part of the multi-nozzle head.

FIG. 4 is a cross-sectional view along a width direction of a main part of the multi-nozzle head.

FIG. 5 is a sectional view along a depth direction of a main part of the multi-nozzle head.

FIG. 6 is an explanatory diagram of a manufacturing process of the multi-nozzle head.

FIG. 7 is a diagram illustrating the operation of the multi-nozzle head.

FIG. 8 is a sectional view of a multi-nozzle head according to another embodiment.

FIG. 9 is a sectional view of a multi-nozzle head according to still another embodiment.

FIG. 10 is a front view of a multi-nozzle head according to still another embodiment.

FIG. 11 is a cross-sectional view along a depth direction of a multi-nozzle head according to still another embodiment.

FIG. 12 is a perspective view of a support member in a multi-nozzle head according to still another embodiment.

FIG. 13 is a sectional view of a multi-nozzle head according to still another embodiment.

FIG. 14 is a perspective view of a projection of a piezoelectric body according to still another embodiment.

FIG. 15 is a sectional view of a multi-nozzle head in a conventional inkjet recording apparatus.

[Explanation of symbols]

 Reference Signs List 17 piezoelectric body 18 support member 26 convex part 27 concave part 29 ink chamber 31 nozzle hole 32 electrode 33 electrode 35 ink supply slit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-208050 (JP, A) JP-A-5-116329 (JP, A) JP-A-3-108549 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/055

Claims (3)

(57) [Claims] 2. The method according to claim 1 , wherein the partition is made of a non-piezoelectric material.
A plurality of ink chambers and nozzles corresponding to these ink chambers, and ejects ink droplets from the corresponding nozzles according to a change in the volume of the ink chambers. A plurality of piezoelectric active portions having elongated electrodes extending in the direction, a member arranged so that a specific surface extending in the longitudinal direction is opposed to each ink chamber, each piezoelectric active portion, The direction of polarization is the same as the direction of the electric field formed by the input signal from the corresponding electrode, the direction of expansion and contraction is the longitudinal direction, and the direction perpendicular to the longitudinal direction of the specific surface caused by the expansion and contraction in the longitudinal direction. An ink jet recording head, wherein the volume of the ink chamber is changed by deformation. 2. The piezoelectric member according to claim 1, wherein the member is a plate-shaped piezoelectric material having a plurality of grooves formed on a surface thereof, and the plurality of elongated protrusions formed between the grooves are formed by the plurality of piezoelectric active portions. 2. The ink jet recording head according to claim 1, wherein: 3. A pre-Symbol Each convex piezoelectric active portion thereof from one side in the longitudinal direction while being polarized in a direction toward the other side, if these sides to elongated electrodes are formed The ink jet recording head according to claim 2, wherein: