JPH05330038A - Ink-jet head - Google Patents

Abstract

PURPOSE:To provide an ink-jet head having high density and high reliability by easily connecting a plurality of converters arranged in a row shape and an external driving circuit positively. CONSTITUTION:A plurality of converters 22 disposed in a row shape have electric contacts 28 and 29 on surfaces orthogonal in the direction of the arrangement of the converters 22, one electric contacts 28 of the electric contacts 28 and 29 are connected by a conductive member 23, and converters 22b are composed in dummy converters, in which the two electric contacts 28 and 29 are conducted electrically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head for an on-demand type ink jet printer which discharges ink droplets in response to a print signal to form an ink image on a recording medium such as recording paper.

[0002]

2. Description of the Related Art The structure of a conventional ink jet head is
It is disclosed in Japanese Patent Publication No. 2-52625.

In this ink jet head, one end of a rod-shaped converter is loaded in the groove between the comb teeth of the printed circuit, and the conductive pattern on the printed circuit and the electrode of the converter are connected by means such as soldering. A circuit contact for driving (energizing and deactivating) the converter is developed on the plane of the printed circuit, and the drive circuit outside the head and the circuit contact are connected using a connecting means.

[0004]

When a plurality of transducers are arranged in a row to increase the density of the recording head, the distance between the transducers becomes very narrow, which makes it difficult to connect to a drive circuit outside the head. Becomes

Therefore, it is important that the transducers arranged in high density and the external drive circuit of relatively low density can be easily and surely connected.

In the structure of the above-mentioned publication, since the circuit contacts electrically connected to the converter are developed on the plane of the printed circuit, the connection with the drive circuit outside the head is formed in a plane. It can be easily performed using wiring means.

However, since the two electric contacts of the converter are formed on two planes which are orthogonal to the surface of the conductive pattern of the printed circuit and which face each other, the comb teeth are formed on the printed circuit and the inter-comb teeth are formed. The groove is loaded with the transducer and the electrical contact of the transducer facing the comb tooth is connected to the conductive pattern on the printed circuit via the comb tooth.

As described above, the conventional invention has the following problems. (1) There is a limit in processing and strength in forming comb teeth with high density. (2) Connection is difficult because the connecting means of the conductive pattern on the printed circuit and the electrical contact of the converter are not developed in a plane.

Therefore, the object of the present invention is to solve these problems, and the purpose thereof is to easily and surely connect a plurality of converters arranged in a row to an external drive circuit. The purpose is to provide a high-density and highly reliable inkjet head.

[0010]

The ink jet head of the present invention deforms an ink chamber corresponding to the converter by selectively applying an electric signal to the plurality of converters arranged in a row. Increase the ink pressure in the ink chamber,
An inkjet head for selectively ejecting ink droplets from nozzles communicating with an ink chamber, wherein the plurality of converters have electrical contacts on a surface orthogonal to the arrangement direction, and the plurality of converters on the one surface. One electrical contact of the converter is connected by a conductive member, and at least one of the plurality of converters is connected.
One is characterized in that the electrical contacts are electrically conducting.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the construction of an embodiment of the ink jet head of the present invention, in which each part is disassembled so that the internal structure can be seen. FIG. 2 is a partial cross-sectional view of the embodiment shown in FIG. The embodiment of the present invention shown in FIG. 1 is composed of a flow path unit and a converter unit in terms of function.

First, the flow path unit will be described. In FIG. 1, elongated cavities 51 that form ink chambers to be described later are formed in two rows at equal intervals in a row on the flow path forming substrate 3, and one end of each cavity is a common ink chamber to be described later. Communicates with the window 41 forming the. The flow path unit is formed by joining the flow path forming substrate 3 so as to be sandwiched between the nozzle substrate 1 and the vibrating plate 8. The ink chamber 5 is provided in the elongated cavity 51 and the window 41 is provided in the window 41. A common ink chamber 4 is formed. The nozzle 2 is formed on the nozzle substrate 1 so as to correspond to the cavity 41.
Therefore, one end of the ink chamber 5 communicates with the nozzle 2.

Next, the converter unit will be described. A rod-shaped laminated piezoelectric element 2 which is a converter serving as a drive source for ejecting ink droplets.
2 are arranged in rows in the X direction of FIG. The laminated piezoelectric element 22 has one half surface in the longitudinal direction fixed to the converter unit substrate 21, and the non-fixed portion protrudes like a beam from the converter unit substrate 21. As shown in FIG. 2, the laminated piezoelectric element 22 has an active portion composed of electrode layers 26 and 27 that alternately intersect at the beam-shaped portion of the laminated piezoelectric element 22, one electrode layer 27 serving as an individual electrode and the other electrode layer 27 serving as an individual electrode. The electrode layer 26 is connected as a common electrode to an external drive circuit (not shown) via the lead frame 25. The arrangement of the laminated piezoelectric element 22 which is a transducer is such that one laminated piezoelectric element 22 corresponds to one ink chamber 5.
Is the same as the interval. In the embodiment shown in FIG. 1, two converter units are mounted corresponding to the two rows of ink chambers 5.

The flow path unit and the converter unit are fixed to each other by a head frame 11. An ink supply pipe 31 is press-fitted and adhered to the head frame 11. Ink is supplied from an external ink tank (not shown) to the common ink chamber 4 of the flow path unit and further to the ink chamber 5 through the ink supply pipe 31 and the ink communication port 33 in the vibrating plate 8. The relationship between the flow path unit and the converter unit will be described with reference to FIG. The portion of the vibrating plate 8 forming the wall of each ink chamber 5 is a diaphragm having island-shaped legs 7 formed on the surface opposite to the ink chamber 5 for each ink chamber. The beam-shaped tip of the laminated piezoelectric element 22 is joined to the foot 7 having a circular shape.

When a voltage is applied between the individual electrode 27 and the common electrode 26 of the laminated piezoelectric element 22 from an external drive circuit (not shown), the active portion of the laminated piezoelectric element 22 contracts in the longitudinal direction, and the ink chamber 5 The diaphragm is bent downward to increase the volume of the ink chamber 5. Due to the expansion of the volume of the ink chamber 5, the ink is supplied from the common ink chamber 4 to the ink chamber 5 through the supply flow path 6. When the voltage application between the individual electrode 27 and the common electrode 26 is released in the subsequent time, the active portion of the laminated piezoelectric element 22 expands to the original length to reduce the volume of the ink chamber 5, and the generated pressure causes the ink chamber 5 to be reduced. A part of the ink that fills the ink is ejected as an ink droplet from the nozzle 2 communicating with the ink chamber 5.

Next, the converter unit of the present invention will be described in more detail with reference to FIGS. 3, 4 and 5.

FIG. 3 is an enlarged view of the converter unit of the embodiment shown in FIG. The converter unit substrate 21 is made by processing an alumina substrate having a thickness of 1 mm. The beam-shaped protrusion 42 is provided for positioning the transducer unit and the head frame 11. As shown in FIG. 2, the laminated piezoelectric element 22, which is a transducer arranged in rows, is
One of the laminated electrodes is connected to an external electrode at the beam-shaped tip of the laminated piezoelectric element, and is further connected to the side electrode 28. The other of the laminated electrodes is connected to an external electrode at the end of the laminated piezoelectric element which is fixed to the converter unit substrate 21, and is connected to an electrode 29 formed on the side surface facing the electrode 28. As shown in FIG. 3, the electrodes 28 provided on the side surfaces of the converters 22 arranged in rows are formed on the surface orthogonal to the arrangement direction X of the converters 22, and the electrodes of the plurality of converters 22 are arranged. 28 are arranged on the same plane. The same applies to the electrode 29 on the opposite side. The laminated piezoelectric elements 22b on both sides of the transducer array are different from the laminated piezoelectric elements 22a between them. While the electrodes of the other laminated piezoelectric element 22a are separated into the individual electrode 29 and the common electrode 28 at portions 35 and 36 in FIGS. 2 and 3, the laminated piezoelectric elements 22 on both sides of the transducer row are separated.
As for b, as shown in FIG. 3, the individual electrode 29 and the common electrode 28 are electrically connected on the side surface.

Transducer unit substrate 2 of laminated piezoelectric element 22
The electrode 29 provided on the joint surface with 1 serves as an electrical contact of the individual electrode and serves as the laminated piezoelectric element 22 and the converter unit substrate 21.
At the same time as the bonding with the conductive pattern 2 provided on the converter unit substrate 21 corresponding to each of the laminated piezoelectric elements 22.
4 is electrically connected. The electrode 28 provided on the other surface of the laminated piezoelectric element 22 is connected to the conductive member 23 as an electric contact of the common electrode. Therefore, the common electrode 28 of each laminated piezoelectric element 22a is electrically coupled by the conductive member 23, and further, via the laminated piezoelectric elements 22b on both sides of the transducer row, the conductive pattern 24 of the transducer unit substrate 21.
It is electrically connected to b. Therefore, the laminated piezoelectric elements 22b on both sides of the transducer row do not function as a dummy transducer for ejecting ink droplets. Also, the lead frame 2
The terminals on both sides of 5 are connected to an external drive circuit as terminals of a common electrode, and inner terminals as terminals of individual electrodes of individual converters except dummy converters.

Next, a method of manufacturing the converter unit of the present invention shown in FIG. 3 will be described with reference to FIGS.

The block 32 of the piezoelectric element in which the electrodes are laminated in the thickness direction has a thickness of 0.5 mm, a width of 4.5 mm and a length of 8 mm, and the active portion has a length of about 4 mm. An electrode 38 made of Ni and Au is formed on the surface by sputtering, and 36 parts and a portion of the electrode corresponding to 35 parts on the opposite surface as shown in FIG. 2 are removed by etching. In addition, the converter unit substrate 21 is
The stripe-shaped conductive patterns 24 are formed at a pitch of 1/90 inch, and the width of the outer pattern 24b is wide. The block 32 of the piezoelectric element is bonded onto the conductive pattern of the converter unit substrate 21 with an adhesive so that the protruding length is about the length of the active portion.
At this time, since the thickness of the adhesive is very thin, the block of the piezoelectric element and the conductive pattern of the converter unit substrate are electrically connected at the joint surface.

After the block 32 of piezoelectric elements and the transducer unit substrate 21 are bonded, the block of piezoelectric elements is cut as shown in FIG. 5 to separate into individual transducers. The cutting is performed between the conductive patterns 24 of the converter unit substrate 21,
Therefore, the pitch in the arrangement direction of the converters is 1/90 inch. As mentioned earlier, the block of piezoelectric elements is 36
Since the electrodes of the part are removed, the individual electrodes 29 and the common electrode 28 are separated from each other in the inner laminated piezoelectric element 22a except both ends, but the laminated piezoelectric elements 22b at both ends are the electrodes 30 in which the individual electrode and the common electrode are one. It is electrically connected. Thereafter, the common electrode 28 of the laminated piezoelectric element 22 is connected by soldering the conductive member 23 made of a Ni plate having a thickness of 30 μm, and the lead frame 25 is soldered to the conductive pattern 24 of the converter unit substrate. This produces the converter unit as shown in FIG.

As described above, in the first embodiment of the present invention, the connection between the common electrode and the conductive member and the connection between the individual electrode and the conductive pattern are carried out by planar bonding between all the transducers. It becomes possible to join a plurality of conversion elements in one process, and high-density electrode connection can be performed with high reliability. Further, in the connection between the common electrode 28 (30) and the conductive member 23 and the connection between the individual electrode 29 (30) and the conductive pattern 24, one surface is made of the same material,
It is easy to select the optimum joining method, and highly reliable joining can be obtained. Particularly, the laminated piezoelectric element 22 used in the present invention is a very brittle material, and the width after cutting is 0.1 mm.
Since there is only such a degree, the step of connecting the common electrode to the external wiring after cutting needs to be performed very carefully. But,
In the present invention, since planar bonding is sufficient, a shearing force that would destroy the laminated piezoelectric element is not applied, and wiring can be performed easily.

Next, another embodiment of the present invention will be described with reference to FIGS.

FIG. 7 is a diagram showing a converter unit of an embodiment of the present invention, and the state of being incorporated in an ink jet head is the same as that of FIG. 1 of the embodiment described above. In this example,
As shown in FIG. 6, the electrodes 38 of the block 32 of the piezoelectric element,
Block 39 of the piezoelectric element because 39 is cut at 36 parts
When the block 32 of the piezoelectric element is cut after bonding the transducer 2 and the transducer unit substrate 21 and separated into individual transducers, as shown in FIG.
Different from the previous embodiment shown in FIG.
The individual electrode and the common electrode of are also separated. Therefore, as shown in FIG. 7, in this embodiment, the conductive member 23 connecting the common electrode 28 has a U-shape, and the conductive member 23 allows the individual electrodes of the laminated piezoelectric elements 22b at both ends and the common electrode. Are connected. Further, in this embodiment, the laminated piezoelectric element 22 is
The electrical contact 29 and the conductive pattern 24 of the converter unit substrate 21 are connected 43 by wire bonding. In this embodiment, since the electrodes 28 and 29 on the surface of the piezoelectric element block are simple as shown in FIG.
Without forming a pattern by etching as in the previous embodiment,
It can be formed by screen printing. Further, since the conductive pattern 24 of the converter unit substrate 21 and the electric contact 29 of the laminated piezoelectric element 22 can be connected by wire bonding with the same stroke for the individual electrode and the common electrode, the manufacturing process is very simple.

Next, another embodiment of the present invention will be described with reference to FIGS.

In the embodiment shown in FIG. 8, a nozzle 62, an ink chamber 65, and a common ink chamber 64 are formed by etching on a flow path forming substrate 63 made of glass. An ink flow path is formed by laminating the vibration plate 68 thereon by adhesion or diffusion bonding. The flow path forming substrate 63 can be made by molding plastic as well as glass. The vibrating plate 68 can be made of a stainless plate, a glass plate, or a plastic plate. The vibrating plate 68 is provided with an ink communication port 69 for supplying ink to the common ink chamber 64 from an external ink tank (not shown). Further, a piezoelectric element 61a, which is a transducer, is adhered to an external position of the vibrating plate 68 corresponding to the ink chamber 65, and a small piece of the piezoelectric element having the same thickness as the piezoelectric element 61a is provided outside the array of the piezoelectric elements. 61b is adhered. Electrodes are formed as electric contacts on the upper and lower surfaces of the piezoelectric element corresponding to the ink chamber 65. When an electric signal is applied between the electrodes, the piezoelectric element is distorted and the diaphragm 68 is displaced. As a result, the volume of the ink chamber 65 changes, and ink droplets are ejected from the nozzle 62 communicating with the ink chamber 65. A means for applying an electric signal to the piezoelectric element of this embodiment from an external drive circuit (not shown) will be described with reference to FIG. The outer surface of the diaphragm 68 of this embodiment has conductivity. This can be obtained by forming a metal film on the surface by vapor deposition or the like when the diaphragm is made of an insulating member such as glass or plastic. Therefore, the electrodes on the lower surface of the piezoelectric element 61 bonded on the vibration plate 68 are electrically connected by the vibration plate 68. Further, the electrodes on the upper and lower surfaces of the small piece 61b of the piezoelectric element are electrically connected to each other because the electrodes are also on the end faces. Therefore, the electrode on the lower surface of the piezoelectric element 61a corresponding to each ink chamber 65 is connected to the upper surface of the small piece 61b of the piezoelectric element as a common electrode. As a result, the individual electrodes and the common electrode for applying an electric signal to the piezoelectric element have their electric contacts spread on the upper surface in a plane. Therefore, in this embodiment, the converter and the external drive circuit can be easily connected by connecting the external drive circuit (not shown) and the electrical contacts on the upper surface of the piezoelectric element 61 with the flexible printed board 70. it can.

[0028]

According to the above configuration of the present invention, a plurality of converters arranged in a row have respective electric contacts on two surfaces orthogonal to the arrangement direction, and the electric power on one surface is changed. The contacts are connected by a conductive member, and the at least one converter is a dummy converter, and the two electrical contacts are electrically connected.
Therefore, the electrode on one side is connected as a common electrode via the conductive member and the dummy converter to the electrical contact of the dummy converter on the other side, and as a result, all the converters are driven. The electrical contacts that connect to the external drive circuit are
The converter is developed in a plane shape on one surface of the converter, and has an effect that the converters arranged at high density and an external drive circuit can be easily connected. In addition, since the structure of the connecting part between the electrode contact of the converter and other electrodes is simple in structure and material, it is possible to select the optimum connecting method and destroy the converter in the connecting process. It is possible to easily provide a highly reliable inkjet head without doing so.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the first embodiment of the present invention.

FIG. 3 is a perspective view showing a configuration of a main part of the first embodiment of the present invention.

FIG. 4 is a perspective view showing a method of manufacturing a main part of the first embodiment of the present invention.

FIG. 5 is a perspective view showing a method of manufacturing a main part of the first embodiment of the present invention.

FIG. 6 is a perspective view showing a method of manufacturing a main part of the second embodiment of the present invention.

FIG. 7 is a perspective view showing a configuration of a main part of the first embodiment of the present invention.

FIG. 8 is a perspective view showing a configuration of a first exemplary embodiment of the present invention.

FIG. 9 is a perspective view showing a configuration of a first exemplary embodiment of the present invention.

[Explanation of symbols]

 1 Nozzle Substrate 2,62 Nozzle 3,63 Flow Forming Substrate 4,64 Common Ink Chamber 5,65 Ink Chamber 8,68 Vibration Plate 11 Head Frame 21 Transducer Unit Substrate 22 Multilayer Piezoelectric Element (Converter) 23 Conductive Member 24 Conductive Pattern 32 Block of Piezoelectric Element 61 Piezoelectric Element (Transducer)

Claims (1)

[Claims] 1. An ink chamber corresponding to the converter is deformed by selectively applying an electric signal to the plurality of converters arranged in a row, and the ink pressure in the ink chamber is increased to thereby form ink in the ink chamber. In an inkjet head for selectively ejecting ink droplets from communicating nozzles, each of the plurality of converters orthogonal to the arrangement direction of the plurality of converters has an electrical contact on both sides, The inkjet head is characterized in that the electrical contacts are connected by a conductive member, and at least one electrical contact on both surfaces of the plurality of converters is electrically conducting.