JP2959106B2 - Inkjet head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer for selectively depositing ink droplets on an image recording medium.

[Conventional technology]

The structure of a conventional ink jet head is disclosed in JP-A-63-25
No. 2,750 or JP-A-63-247051.

These are composed of a number of parallel flow paths spaced from each other in the direction in which the ink discharge nozzles are arranged, and the flow paths extend at the top, the bottom, and in the longitudinal direction of the flow path and perpendicular to both the longitudinal direction and the nozzle arrangement direction. It is partitioned by the side wall.
One end of the flow path is connected to a nozzle plate having a plurality of nozzles, and the other end is connected to ink supply means for replenishing each channel with ink. The side wall is partially or entirely made of a piezoelectric material, and causes a deformation parallel to the array direction such as a shearing mode by an electric actuating means. This was to eject ink droplets. These prior arts have the characteristic that a high-density multi-nozzle inkjet head can be configured.

[Problems to be solved by the invention]

However, when the density of the nozzles is increased and the interval between adjacent nozzle openings is reduced, there is a problem that a nozzle row cannot be formed on a single nozzle plate. Also,
As the nozzle density increases, the cross-sectional area of the nozzle opening decreases. However, it is not easy to accurately form a hole with a small cross section in a thick plate, and the nozzle plate becomes thin,
There are problems such as a decrease in strength and generation of vibration.

Therefore, an object of the present invention is to solve these problems, and the object thereof is to achieve a high density, a high number of nozzles,
Another object is to provide a highly reliable ink jet head.

[Means for solving the problem]

The ink jet head of the present invention has a protruding portion in which a side wall that partitions adjacent flow paths of a number of parallel flow paths having openings arranged in an array on a substrate end face protrudes from the substrate end face, A nozzle is formed by the protrusion and an edge of the nozzle substrate.

Further, in this configuration, the shape of the opening of the flow path is such that the average dimension in the direction perpendicular to the array direction is larger than the average dimension in the array direction, or the height of the protrusion is equal to the thickness of the nozzle substrate. Alternatively, a part or the whole of the side wall is made of a piezoelectric material, and the side wall is deformed by an electric actuating means, or a part of the edge of the nozzle substrate that forms a nozzle with a protruding portion of the side wall. , Which is thicker on the nozzle outlet side.

Furthermore, the vicinity of the end surface of the substrate forming the protruding portion is formed of a substrate end surface member different from a member that constitutes most of the flow path.

〔Example〕

 Embodiments of the present invention will be described in detail below.

One embodiment of the present invention will be described with reference to FIG. As shown in the perspective view of FIG.
A plurality of flow paths 55 having a cross section whose average dimensional width of the flow path is smaller than the average dimensional height of the flow path in a direction perpendicular to the array direction 60 are formed in parallel with each other, and are connected to the substrate end face 21. I have. The substrate end face 21 to which the flow path 55 is connected is in the array direction.
A part of the side wall 37 that divides each flow path 55 into 60 has a protruding projection 38
, And each protrusion 38 is formed linearly in the array direction 60. The nozzle substrate 1 whose edge is processed so as to be in close contact with each of the protruding portions 38 arranged in a straight line on the substrate end face 21 is joined so as to sandwich the protruding portion 38, and the protrusion of the side wall 37 adjacent to each flow path 55. Nozzle opening 2 surrounded by protruding portion 38 and nozzle substrate 1
Can be formed linearly in the array direction 60.

FIG. 2 shows the structure shown in FIG. 1 in a front view (a) from a nozzle opening and a longitudinal sectional view (b) of a flow path. After the substrate end surface 21 to which the flow path 55 is connected is polished flat, it is processed using a diamond cutting disk so that the height of the protruding portion 38 is equal to that of the nozzle substrate 1. By setting the processing direction in the array direction 60, the projections 38 having a rectangular cross section can be formed simultaneously in all the flow paths 55 linearly in the array direction 60. The nozzle substrate 1 is typically formed by processing a nickel plate having a thickness of 50 to 200 μm so that an edge is a straight line perpendicular to the surface, and bonding the substrate to the substrate end surface 21 so as to be in close contact with the protruding portion 38 using an adhesive. Is done.

FIG. 3 is a view showing a flow path of an embodiment in which a flow path to which the method for forming a nozzle of an ink jet head of the present invention is applied is a pressure generating chamber made of a piezoelectric substance. The flow path formed at the joint between the substrates 20a and 20b made of piezoelectric materials polarized in opposite directions has an average dimension width of the flow path in the array direction perpendicular to the array direction. It has a rectangular cross section smaller than that, and is formed in parallel with each other. Each flow path forms a pressure generating chamber 5. In FIG. 3A, the electrodes 40a and 40b formed in the same pressure generating chamber 5 are electrically connected, and are connected to the driving driver element 70 for each channel. The driver element 70 outputs a high voltage output or a low voltage output from the DC current 73 in accordance with the control signal 72 from the control unit 71,
Feed selectively to 40. Each of the pressure generating chambers 5 is divided into two groups (one even number and one odd number), and each group is divided into time groups and driven alternately.
As shown in FIG. 3 (b), the deformed portion 36, which is a side wall that divides the selected pressure generating chamber 5a and the adjacent pressure generating chamber 5b, is perpendicular to the polarization directions 50 and 51 of the piezoelectric substance. To
When the driver element connected to the selected pressure generating chamber 5a and the adjacent pressure generating chamber 5b is controlled, the deforming portion 36 made of the piezoelectric material deforms in the shear mode, and reduces the volume of the selected pressure generating chamber 5a. Then, a pressure is generated in the ink 6 filling the pressure generating chamber 5a. The generated pressure propagates in the pressure generating chamber 5a, and causes ink droplets to be ejected from a nozzle (not shown).

FIG. 4 shows a front view (a) from a nozzle opening and a longitudinal sectional view (b) of a flow channel according to another embodiment of the present invention. In the flow path, two rows of flow paths 55a and 55b are formed on the substrate 20 so as to be shifted from each other by a half pitch position. Channel 55a,
After the end face of the board to which 55b is connected is polished flat,
8 is processed using a diamond cutting disk so that the rectangular section has a height equal to that of the nozzle substrates 1a and 1b and is arranged in a straight line in the direction of the array. The nozzle substrates 1a and 1b are processed so that the edge is a straight line perpendicular to the surface, and the nozzle substrate 1b is processed in parallel so that there is no gap between two rows of flow channel arrays, and an adhesive is used. It is joined to the substrate end face 21 so as to be in close contact with the protrusion 38.

FIG. 5 is a longitudinal sectional view of a flow channel according to another embodiment of the present invention. In the embodiment shown in FIG. 2 and FIG. 4, the members constituting the flow path are exposed at the nozzle end surface. A so-called flight curve occurs in which the ejected ink droplet does not fly perpendicular to the nozzle surface. In particular, the third
When the flow path is a pressure generating chamber as in the embodiment of the figure,
The wettability with the ink becomes unstable. In FIG. 5, the substrate end face member 3 is made of a material having good wettability with ink.

FIG. 6 is a longitudinal sectional view of a flow channel according to another embodiment of the present invention. The edge 11 of the nozzle substrate 1 on the side of the nozzle opening 2 formed on the end face of the flow path opening protrudes,
The height of the protruding portion 38 at the end face of the flow path opening is also increased according to the protruding edge 11. The nozzle opening 2 of this embodiment has a two-dimensional convex shape, and is effective for stabilizing the ink meniscus in the nozzle opening 2.

〔The invention's effect〕

As described above, according to the present invention, a substrate having a flow path having openings in an array at the end face of the substrate is processed such that the side walls defining adjacent flow paths protrude from the end face of the substrate. However, simply by combining with the edge of the nozzle substrate, there is an effect that a high-density nozzle can be simultaneously formed with high precision by an easy processing method. In addition, by appropriately selecting the substrate end face member or by thickening the edge of the nozzle substrate, it is possible to stabilize the nozzle meniscus, and to provide an ink jet head having excellent flight stability and ink ejection stability. Have.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the ink jet head of the present invention. FIGS. 2 (a) and 2 (b) are a front view from the nozzle opening of the embodiment of FIG. 1 and a longitudinal sectional view of the flow channel. 3 (a) and 3 (b) are cross-sectional views illustrating the operation of the pressure generating chamber flow path according to the embodiment of the present invention. 4 (a), (b), FIG. 5,
FIG. 6 is a diagram showing the vicinity of the nozzle opening of the embodiment of the ink jet head of the present invention. DESCRIPTION OF SYMBOLS 1 ... Nozzle board 2 ... Nozzle opening 3 ... Board end surface member 20 ... Board 37 ... Side wall 38 ... Projecting part 55 ... Flow path

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/045 800 B41J 2/055 800

Claims (6)

(57) [Claims] A plurality of parallel flow paths having openings arranged in an array on an end face of the substrate, wherein a side wall defining adjacent flow paths has a protrusion protruding from the end face of the substrate; An ink jet head, wherein a nozzle is formed by a part and an edge of a nozzle substrate. 2. The ink jet head according to claim 1, wherein the shape of the opening of the flow path is such that an average dimension in a direction perpendicular to the array direction is larger than an average dimension in the array direction. 3. The ink jet head according to claim 1, wherein the height of the protrusion is equal to the thickness of the nozzle substrate. 4. An ink jet head according to claim 1, wherein a part or the whole of said side wall is made of a piezoelectric material, and said side wall is deformed by an electric actuating means. 5. The substrate according to claim 1, wherein the vicinity of the end surface of the substrate forming the protruding portion is formed of a substrate end surface member different from a member constituting most of the flow path. Ink jet head. 6. The ink jet head according to claim 1, wherein a portion of the edge of the nozzle substrate that forms the nozzle with the protrusion of the side wall is thicker on the nozzle outlet side.