JP3555638B2 - Ink jet recording head - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to an ink jet recording head in which a nozzle plate, a flow path forming member, and a vibration plate are laminated, and a piezoelectric vibrator in a flexural vibration mode is mounted on a surface of the vibration plate.
[0002]
[Prior art]
An ink jet recording head in which a nozzle plate, a flow path forming member, and a vibration plate are stacked, and a piezoelectric vibrator in a flexural vibration mode is mounted on the surface of the vibration plate, since most of these members are made of ceramic. Since the members can be laminated in the state of a green sheet and fired, the members can be fixed without using an adhesive, so that there is an advantage that a joining process is unnecessary and a manufacturing process can be simplified. .
In such a recording head, a flexible cable is connected by soldering to a connection terminal extended from an individual electrode of the piezoelectric vibrator, and receives a drive signal from an external drive circuit to discharge ink droplets in accordance with print data.
[0003]
[Problems to be solved by the invention]
However, in a recording head in which a large number of nozzles are formed in order to improve the printing quality and the printing speed, the number of individual electrodes becomes extremely large. The soldering area used for connection with the flexible cable overflows from the connection terminal and flows to the drive electrode, and the flexible metal, such as gold (Au), forming the individual electrode is melted by the molten solder. Eating "gold-eating phenomenon" occurs. When such a gold erosion phenomenon occurs, the conductive relationship between the individual electrode and the connection terminal is broken, so that there is a problem that the ink droplet cannot be ejected.
[0004]
The present invention has been made in view of such a problem, and an object of the present invention is to provide an ink jet recording head capable of preventing erosion of an individual electrode due to soldering between the individual electrode and a flexible cable. It is to provide.
[0005]
[Means for Solving the Problems]
In order to solve such a problem, according to the present invention, a pressure generation chamber which communicates with a nozzle opening and a common ink chamber and has one surface sealed by a lid member, and a pressure generation chamber formed on a surface of the lid member. A piezoelectric vibrator formed to correspond to the chamber, an individual electrode forming one pole of the piezoelectric vibrator, and formed on the surface of the lid member so as to face the individual electrode; In an ink jet recording head having a connection terminal serving as a connection region of a flexible cable for connecting an electrode, an auxiliary electrode is connected to one end of the individual electrode, and the auxiliary electrode is drawn out to a connection terminal formation region . A projection is formed on the auxiliary electrode side to prevent the flow of solder for connecting the flexible cable and the connection terminal to each other.
[0006]
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 is an assembled perspective view showing an embodiment of a recording head according to the present invention, and FIG. 2 is a view showing a sectional structure in the vicinity of one pressure generating chamber. And a common electrode 4 serving as one of the poles is formed on the surface of the zirconia thin plate having a thickness of about 10 μm. The vibrators 5, 5 'are fixed, and individual electrodes 6, 6' made of a relatively flexible metal layer such as gold are formed on the surface thereof. Further, the individual electrodes 6, 6 'and connection terminals 7, Auxiliary electrodes 21 and 21 ′ which are electrically independent of each other and which are electrically connected to 7 ′ are formed at positions facing the individual electrodes 6 and 6 ′.
[0007]
Further, it is desirable that the connection electrode 7 be formed so as to have a protruding portion 7a so that the upper portions of the auxiliary electrode sides 21 and 21 'are slightly raised as shown in FIG.
[0008]
Reference numerals 7 and 7 denote connection terminals formed on the sides of the first lid member 2, which are formed when the individual electrodes 6 and 6 'are formed via the auxiliary electrodes 21 and 21 as shown in FIG. A part is drawn out to this point, and is electrically connected to the individual electrodes 6, 6 'with a gap G therebetween.
[0009]
Reference numeral 8 denotes a spacer which is formed by piercing a through hole in a ceramic plate made of zirconia (ZrO ₂ ) having a thickness suitable for forming the pressure generating chambers 3 and 3 ′, for example, 150 μm. Both surfaces are sealed by the lid member 9 and the first lid member 2 to form the above-described pressure generating chambers 3 and 3 '.
[0010]
Reference numeral 9 denotes a second lid member, which is a communication hole 10 and 10 'for connecting ink supply ports 13 and 13' and pressure generating chambers 3 and 3 'described later to a ceramic plate also made of zirconia or the like; Nozzle communication holes 11 and 11 ′ connecting the other end of the pressure generating chambers 3 and 3 ′ with the other are formed and fixed to the other surface of the spacer 8.
[0011]
These members 2, 8, and 9 are formed into a predetermined shape by forming a clay-like ceramic material, laminated, and fired to form the actuator unit 1 without using an adhesive.
[0012]
Reference numeral 12 denotes an ink supply port forming substrate, which also serves as a fixed substrate of the actuator unit 1 and has common ink chambers 15 and 15 and pressure generating chambers 3 and 3 'to be described later at one end of the pressure generating chambers 3 and 3'. Are provided, and the other end sides of the pressure generating chambers 3, 3 'are provided with nozzle communication holes 14, 14' connected to the nozzle openings 18, 18 '.
[0013]
Reference numeral 19 denotes a common ink chamber forming substrate which is provided with common ink chambers 15 and 15 'for receiving inflow of ink from an ink tank (not shown), and nozzle communication holes 16 and 16' connected to the nozzle openings 18 and 18 '. The other surface is sealed by a nozzle plate 17 to form common ink chambers 15, 15 '.
[0014]
Reference numeral 17 denotes the aforementioned nozzle plate, which has nozzle openings 18 and 18 so as to communicate with the pressure generating chambers 3 and 3 'via the nozzle communication holes 11, 14, 16 and the nozzle communication holes 11', 14 ', 16'. 'Has been formed.
[0015]
The ink supply port forming substrate 12, the common ink chamber forming substrate 19, and the nozzle plate 17 are fixed to each other by an adhesive layer such as a heat-sealing film or an adhesive, and are integrated into the channel unit 20.
[0016]
The flow path unit 20 and the above-described actuator unit 1 are fixed with a heat welding film, an adhesive, or the like to form a recording head.
[0017]
Numeral 30 denotes a flexible cable having lead portions 31 and 31 'having a length capable of connecting the recording head and the drive circuit, and having a width W at a central portion capable of straddling the connection terminals 7 and 7' of the actuator unit 1. A flexible film provided with convex portions 32, 32 'is used as a base material 33, and connection portions 35, 35' and conductive patterns 36, 36 for forming a conductive relationship therewith and connecting to an external drive circuit are formed on the surface thereof. 'Is formed. The base material is desirably made of a material that can withstand heat during soldering, such as polyimide.
[0018]
FIG. 4 shows an embodiment of the above-described flexible cable 30, in which the protrusions 32, 32 'correspond to the arrangement pitch of the connection terminals 7, 7' of the actuator unit 1 and are suitable for solder connection. 35, 35 'are formed.
[0019]
These connecting portions 35 and 35 'are divided into two in the longitudinal direction of the cable, and one half (the lower one in the drawing) is connected to the conductive pattern 36 of the lead portion 31 and the other half (the upper one in the drawing). Is connected to the conductive pattern 36 'of the lead portion 31'.
[0020]
In addition, common electrode connection patterns 38, 38 'for connecting the electrodes 4, 4' to an external drive circuit are formed at positions overlapping the common electrodes 4, 4 ', and the surfaces other than the soldering area are formed. It is covered with an insulating protective film such as a resist.
[0021]
In the state where the solder paste is applied to the connection terminals 7 or the connection portions 35, 35 'thus configured, the positioning marks 24, 24 and the common electrode connection patterns 38, 38' of the flexible cable 30 are formed. When the marks 39, 39 'formed on the flexible cable 30 are aligned with each other, the connecting portions 35, 35' of the flexible cable 30 match the connecting terminals 7, 7 'of the actuator unit 1.
[0022]
In this state, when the surface of the base material 33 of the flexible cable 30 is heated to a temperature sufficient to melt the solder paste, a part of the molten solder H overflows and flows to the individual electrode 6 side. The resist layer 40 that insulates the surface of the connection terminal 30 is peeled further to the upper electrode 6 side than the protruding portion 7a at the end of the connection terminal 7, and the conductive pattern such as copper continuous to the connection portion 35 is exposed. Therefore, as shown in FIG. 5B, the solder H that has overflowed from the protruding portion 7a at the end of the connection terminal 7 is exposed to the conductive pattern exposed near the protruding portion 7a at the end of the connection terminal 7. The good wettability of the solder attracts and attracts the solder to prevent the solder from adhering to the auxiliary electrodes 21 and further to the individual electrodes 6.
[0023]
Even if it flows to the surface of the auxiliary electrode 21 without being adsorbed by the conductive pattern, it is cooled rapidly and cannot flow to the individual electrode 6 because the temperature is relatively low.
[0024]
FIG. 6A shows another embodiment of the present invention. In this embodiment, solder wettability is low under the connection terminal 7 and silver or copper or the like constituting the connection terminal 7 is used. A film 41 made of aluminum or chromium capable of securing the adhesion between the metal and the lid member 2 is formed, and a part 40 a of the film 40 is extended to the vicinity of the individual electrode 6 on the surface of the connection terminal 21. .
[0025]
According to this embodiment, the solder H overflowing during soldering is repelled without being able to secure the wettability with the film 41a, and the connection terminal 7 having good wettability with the solder as shown in FIG. Is prevented from flowing to the individual electrode 6 side. In the above-described embodiment, a region having low wettability with respect to solder is formed between the connection terminal and the individual electrode by extending the film 41. However, the auxiliary electrode 21 itself is formed by the wettability of solder such as aluminum or chrome. It is apparent that the same effect can be obtained even if the gap G is secured between the connection terminal 21 and the end 6a of the individual electrode 6 by using a material having low property.
[0026]
FIG. 7A shows an enlarged view of the vicinity of the connection terminal. The individual electrodes 6 formed on the surface of the piezoelectric vibrator 5 are separated from the end of the connection terminal 7 by a certain gap G. An epoxy resin or a polyimide resin so as to be conductively connected to the auxiliary electrode 21 and to fill the gap G from the end of the connection terminal 7 and further to the piezoelectric vibrator 5 side beyond the end 6 a of the upper electrode 6. The insulating layer 42 is formed of a material having heat resistance such as that described above and which is not eroded by solder.
[0027]
When the solder paste is heated from the surface of the base material 33 of the flexible cable 30 to a temperature sufficient to melt the solder paste, a part of the molten solder H overflows and flows to the individual electrode 6 side. On the 6th side, there is a raised portion of the insulating layer 42, so that the molten solder cannot get over this as shown in FIG. 7B, and even if it gets over it, it is accommodated in this recess. It cannot flow to the individual electrodes 6.
[0028]
【The invention's effect】
As described above, according to the present invention, the flow of solder at the time of soldering a flexible cable can be stopped by the protruding portions of the connection terminals, and the erosion of individual electrodes by solder can be reliably prevented.
[Brief description of the drawings]
FIG. 1 is an assembled perspective view showing one embodiment of an ink jet recording head of the present invention.
FIG. 2 is a cross-sectional view showing the structure of the same ink jet recording head in the vicinity of a pressure generating chamber.
FIG. 3 is a diagram illustrating a structure of a connection terminal formed on a surface of an actuator unit.
FIG. 4 is a view showing one embodiment of a conductive pattern formed on a flexible cable connected to the ink jet recording head.
FIGS. 5A and 5B are diagrams showing an embodiment of the present invention in an enlarged manner in the vicinity of a connection terminal and a diagram showing a state in which a flexible cable is soldered, respectively.
6 (a) and 6 (b) are a diagram showing an embodiment of the present invention in an enlarged view near a connection terminal and a diagram showing a state in which a flexible cable is soldered.
FIGS. 7 (a) and 7 (b) are a diagram showing an embodiment of the present invention in an enlarged view in the vicinity of a connection terminal and a diagram showing a state in which a flexible cable is soldered.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Actuator unit 2 First lid member 3, 3 'Pressure generating chamber 4, 4' Common electrode 5, 5 'Piezoelectric vibrator 6, 6' Individual electrode 7, 7 'Connection terminal 18, 18' Nozzle opening 20 Flow Road unit 21 Auxiliary electrode 30 Flexible cable 31, 31 'Lead part 32, 32' Convex part 33 Base material 35, 35 'Connection part H Solder

Claims (2)

A pressure generating chamber which is in communication with the nozzle opening and the common ink chamber and one surface of which is sealed by a lid member, and a piezoelectric vibrator formed on the surface of the lid member so as to correspond to the pressure generating chamber, An individual electrode forming one pole of the piezoelectric vibrator; and a connection terminal formed on a surface of the lid member so as to face the individual electrode and serving as a connection region of a flexible cable for connecting an external circuit and the individual electrode. In the ink jet recording head having
An auxiliary electrode is connected to one end of the individual electrode and drawn out to a connection terminal forming area, and at the auxiliary electrode side of the connection terminal, solder for connecting the flexible cable and the connection terminal is prevented from flowing. An ink jet recording head formed with a protrusion. 2. The ink jet recording head according to claim 1, wherein the surface of the auxiliary electrode is formed of a conductive material having a lower wettability to solder than the connection terminal.

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