JPH07108681A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To make positioning of electrodes easy, and improve productivity in mass production with joining made in a lump by a method wherein electrodes of a piezoelectric element are joined flush to external conductor patterns. CONSTITUTION:A laminated piezoelectric element 1 is divided in the direction extending over the entire length of passages into plural numbers corresponding to the number of the passages, and is constructed so that each of the divided elements operates independently as an actuator. A common electrode 3a and a selective electrode 3b of the piezoelectric element 1 are extended over the same plane and joined to a common electrode pattern 4a and a selective electrode pattern 4b of an external conductor with solders 6 and 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head, and more particularly to a so-called multi-nozzle ink jet recording head having a large number of ink jet nozzles.

[0002]

2. Description of the Related Art FIG. 9 is a sectional view of a conventional ink jet head. FIG. 9 (a) is a longitudinal sectional view (a sectional view taken along the line AA of FIG. 9 (b)), and FIG. 9 is an enlarged cross-sectional view taken along the line BB of FIG. 9A, where 11 is a substrate, 12 is a piezoelectric element, 12a is a non-driving piezoelectric element, 12b is a driving voltage element,
13 is a flow path plate, 13a is an ink flow path, 13b is a wall portion, 1
4 is a common liquid chamber constituent member, 14a is a common liquid chamber, 15 is an ink supply pipe, 16 is a nozzle plate, 16a is a nozzle, 17 is a drive circuit printed board (PCB), 18 is a lead wire, 19 is a drive electrode, Reference numeral 20 is a groove that divides the driving piezoelectric element 12b and the non-driving piezoelectric element 12a, 21 is a protective plate, and 22 is a protective plate.
Is a fluid resistance member, and 23 and 24 are internal electrodes (hot electrodes 2
3, the ground electrodes 24) and 25 are upper partition plates.

FIG. 10 shows the drive electrode 19 and the PCB of FIG.
FIG. 1 is an enlarged view of a main part showing a conventional connection (wire bonding) with a (printed circuit board) 17, in which 19a is an electrode on a non-driving piezoelectric element 12a, 19b is an electrode on a driving piezoelectric element 12b, and 19c is a piezoelectric element. Both end electrodes, 19d are common electrodes (ground), and as shown in the figure, the electrodes 1 of each piezoelectric element
The thin lead wires 18 connect 9b, 19c, and 19d to the corresponding electrodes on the PCB 17.

However, according to the above-mentioned conventional technique, the head side electrode and the PCB electrode need to be plated with gold, which is expensive, and the current flowing through the common electrode (ground electrode) is different from that of the electrodes of the respective piezoelectric elements. Since it is the total of the currents flowing through the (hot electrodes), it is necessary to increase the current capacity. Therefore, it is necessary to perform wine bonding several times or to perform soldering or the like in a separate process, which requires time and cost, resulting in cost increase.

FIG. 11 is a view showing an example of joining a piezoelectric element electrode and a signal line electrode disclosed in Japanese Patent Laid-Open No. 55-86765, in which 30 is arranged on one side of a piezoelectric element 31. Upper electrode, 31 a piezoelectric element, 32 a soldering part,
33 is a selection electrode, 34 is a common electrode, 35 is a head body,
Reference numeral 36 denotes a lower electrode disposed on the other side of the piezoelectric element 31, and as shown in the figure, the electrodes 30, 3 are provided above and below the piezoelectric element 31, respectively.
6 is provided, and the upper electrode 30 is soldered to select electrode 33.
And the lower electrode 36 is joined to the electrode of the vibration plate arranged on the pressure chamber.

However, according to the method disclosed in Japanese Patent Laid-Open No. 55-86765, when the number of piezoelectric elements is increased due to the progress of integration of orifices due to the improvement of image quality, the selection electrode 33 arranged on the head main body 35. The arrangement becomes complicated, the process takes time, the distance between the electrodes becomes short, and there is a risk of short circuit.

In order to solve the above problems, the present applicant has
Previously, an ink jet recording apparatus has been proposed in which an electrode pattern provided on a substrate is separated into patterns at the same time as slitting each piezoelectric element so that the piezoelectric element is electrically connected to the outside independently. 73347
Issue).

12 and 13 are tilted views for explaining an example of the ink jet recording head previously proposed by the present applicant, and FIG. 14 is a sectional view taken along the line AA of FIG.
0 is usually made of silicon, ceramic, glass, resin, etc., and the electrode is usually the electrode 4 for connecting the piezoelectric element driving IC electrode.
1a, an external lead wire connecting electrode 41b, and a ground electrode 41c, which are patterned and applied on the substrate 40. In this way, the piezoelectric element 42 is bonded to the substrate 40 having the electrodes patterned by approximate positioning, for example, by means such as adhesion (FIG. 12). Next, the slit 4 is formed on the piezoelectric element 42.
The processing of No. 3 is performed by cutting, for example (FIG. 13).
8 slits / mm by processing the slit 43 to have a width of 30 to 40 μm and the piezoelectric element 42 to have a width of about 80 to 90 μm.
It is possible to achieve a degree of integration. This can be sufficiently processed with an ordinary dicing saw or the like.

FIG. 14 is a view after the slit 43 is formed as described above. By this slit processing, the piezoelectric element 42 is substantially separated, and at the same time, the electrode patterns are separated / independent. That is, at this time, the substrate 40 is partially processed at the same time as the piezoelectric element 42. Also, the substrate 40
The front surface (section M in FIG. 14) is not processed so as not to separate the ground electrode 41c. After that, the driving IC 44 (where the electrodes are arranged according to the pitch of the pattern of the separated electrodes) is attached by a chip flow or the like. By appropriately selecting the material of the substrate 40, it becomes possible to sufficiently dissipate heat from the drive IC 44.

However, according to the technique previously proposed by the applicant of the present invention, the slit processing is interrupted on the front surface of the piezoelectric element so as not to separate the ground electrode of each piezoelectric element, and the common electrode is used. The piezoelectric element may be damaged, resulting in poor yield.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and in particular, in the electrical connection from a high density integrated actuator to the outside,
It is an object of the present invention to provide an ink jet recording head having improved workability and assemblability, cost reduction, and reliability.

[0012]

In order to achieve the above object, the present invention provides: (1) a plurality of channels for containing a recording liquid;
In an ink jet recording head having a plurality of nozzles communicating with each of the flow passages and a plurality of actuators for changing the volume in the flow passages and ejecting the recording liquid from the nozzles, the actuators include a substrate. ,
A laminated piezoelectric element formed on the substrate, wherein the laminated piezoelectric element is divided into a plurality of flow channels over the entire length of the flow channel in the longitudinal direction, and each of them is independently separated to operate as an actuator. And the selection electrode and the common electrode are connected to the outer conductor pattern on the same plane, and (2) In (1), the selection electrode and the outer conductor pattern are selected. The electrode is joined by solder, and the common electrode and the common electrode of the outer conductor pattern are joined by an anisotropic conductive film. Further, (3) in (1) or (2) above, The common pattern portion of the outer conductor pattern has a slit that intersects the longitudinal direction of the flow path, and further, (4) in any one of the above (1) to (3), The through electrode pattern and the selection electrode pattern are integrally held by a film member, and (5) the same as the laminated piezoelectric element having a common electrode region and a selection electrode region separated on the same surface. A substrate having a common electrode area and a selection electrode area separated from each other is bonded to the common electrode area and the selection electrode area facing each other, and the laminated piezoelectric element has a total length in the longitudinal direction of the flow path. The electrodes in the selection electrode region of the substrate are separated in the same manner as in the laminated piezoelectric element, and the electrodes in the common electrode region of the substrate are partially in the same manner as the laminated piezoelectric element. Separated and not separated on the edge side, and (6) a laminated piezoelectric element having a common electrode region and a select electrode region separately on the same surface, and a common electrode region and a select electrode region on the same surface. Minute With the substrate, the common electrode area and the selection electrode area are bonded to face each other, the laminated piezoelectric element is divided into a plurality of flow channels over the entire length in the flow channel longitudinal direction, The electrodes of the selection electrode area and the common electrode area of the substrate are also separated similarly to the laminated piezoelectric element, and the conductors on the side surfaces of the common electrode area of the substrate are electrically connected to the electrodes of the common electrode area on the substrate. Further, (7) In (5) or (6) above, conductor patterns are arranged in the vicinity of the edge on the side of the selection electrode region on the substrate, and the conductor patterns are soldered to the outer conductor pattern. To be
(8) In the above (5) to (7), the substrate has a groove intersecting with the flow path direction, and escape of a conductive adhesive that bonds the piezoelectric element and the substrate to each other. The feature is that it is a groove.

[0013]

When the piezoelectric element is cut and independently divided, the entire length is cut to improve the productivity as compared with the conventional technique in which the cutting is stopped midway. By joining the conductor pattern and the conductor pattern on the same plane, it becomes easy to align the electrodes, and it is possible to perform collective joining to improve mass productivity.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional view of an essential part for explaining an embodiment of an ink jet recording head according to the present invention.
Is a piezoelectric element, 2a is an internal common electrode, 2b is an internal selection electrode, 3a is an external common electrode, 3b is an external selection electrode, 4 is F.
With a PC (flexible printed cable), the FPC4
Is composed of a common electrode pattern 4a, a selection electrode pattern 4b, an upper cover film 4c and a lower cover film 4d. 6 and 7 are solder, and the same figure shows the laminated piezoelectric element 1 and the FPC.
4, the external common electrode 3a and the common electrode pattern 4a are joined by thermocompression bonding with the solder 6 at the joint A, and the joint B
Then, the external selection electrode 3b and the selection electrode pattern 4b are bonded by thermocompression bonding with the solder 7.

FIG. 2 shows the laminated piezoelectric element 1 with external electrodes 3a,
In the cross-sectional view when 3b is provided, the external common electrode 3a is in close contact with one side surface to conduct electricity to the entire internal common electrode 2a, and extends from the side surface to the upper surface. Similarly, the external selection electrode 3b is The other side surface is electrically connected to the internal selection electrode 2b, extends from the side surface to an upper surface, and is disposed on the same common surface as the external common electrode 3a.

After the external electrodes 3a, 3b are formed on the laminated piezoelectric element as described above, the laminated piezoelectric element is formed together with the external electrodes 3a, 3b with a dicing saw or the like at a predetermined pitch along the entire longitudinal direction of the ink flow path. By cutting (grooving) into a desired number over, the laminated piezoelectric element is separated into a plurality of CH (channel) actuators having external electrodes 3a and 3b, and then, as shown in FIG. The electrodes (external conductor patterns) 4a and 4b of the FPC 4 for driving each actuator are connected to the external electrodes 3a and 3b, respectively.
Is solder-plated in advance, and the solder-plated portion is thermally pressed in the direction of the arrow.

FIG. 3 is a plan view of the FPC 4 (II in FIG. 1).
In the plan view of line I-III), the shaded portion in the figure indicates the electrode surface. In FIG. 3, the FPC 4 has one common electrode pattern 4a and a plurality of selection electrode patterns 4b arranged at a predetermined pitch held by cover films 4c and 4d so as to be integrated. When the FPC 4 is bonded to the actuator, the external selection electrode 3b and the external selection electrode pattern 4b are
Although the external common electrode 3a is bonded to the pair 1, the external common electrode 3a is bonded to one common electrode. Therefore, if a large amount of solder is used for solder bonding, the common electrode and the selection electrode are short-circuited due to the solder protruding. I will let you. Therefore, in order to escape this solder squeeze out, for example, a slit S that intersects the ink flow path at a right angle is provided in the common electrode pattern corresponding to the joint A, or the joint member is anisotropically conductive. A film is used to maintain the disconnection of the protruding portion and to ensure the insulation between the selection electrode and the common electrode.

In the above embodiment, the upper cover film 4c of the FPC 4 is removed at the portions corresponding to the joints A and B, but it may not be removed. Further, it is advantageous that the joint portions A and B are separated from the effective portion C of the piezoelectric element as much as possible during the heat pressure contact, because the deterioration of the piezoelectric element due to the heating during the heat pressure contact does not easily occur. Further, if the amount of solder plating is too large, even if the slit S or the like is provided, there is a risk of short-circuiting between adjacent electrodes or between the electrodes in the groove direction (stacking direction) due to protrusion after joining, so the amount of solder plating should be as small as possible. It is advisable to ensure electrical continuity and bonding strength.

Next, a second embodiment of the ink jet recording head according to the present invention will be described. In this second embodiment, after the external electrodes 3a and 3b are attached to the laminated piezoelectric element 1, the laminated piezoelectric element 1 is attached. Is bonded to the substrate 8 on which the conductor pattern is arranged, and then the laminated piezoelectric element 1 and the substrate 8 are simultaneously subjected to the groove processing 8a, and then the FPC is applied to the substrate 8.
The outer conductor patterns of No. 4 are joined together.

FIG. 4 is a sectional view for explaining a second embodiment of the present invention. In the figure, 8 is a substrate, 9a is a common conductor pattern on the substrate, 9b is a selective conductor pattern on the substrate, and 10 is a conductor pattern. Is a conductive adhesive, and the external electrodes (external common electrode 3a, external selection electrode 3b) of the laminated piezoelectric element 1 and the electrode patterns (common electrode pattern 9a, selection electrode pattern 9b) on the substrate 8 are bonded by the adhesive 10, respectively. The electrode patterns on the substrate 8 are joined to the external conductor patterns (common electrode patterns and selection electrode patterns on the FPC 4) by the solder 6 (7).

FIG. 5a is a plan view of the substrate 8 shown in FIG. 4, and the hatched lines show the electrode patterns (common electrode pattern 9a and selection electrode pattern 9b) arranged on the substrate 8.
5b is a plan view of the FPC 4 shown in FIG. 4, in which 4a is a common electrode pattern and 4b is a selection electrode pattern.

In the second embodiment, first, the external common electrode 3a of the piezoelectric element 1 is connected to the common conductor pattern 9 on the substrate 8.
After the external selection electrode 3b is joined to a by the conductive adhesive 10 or the like on the selection conductor pattern 9b on the substrate 8, the piezoelectric element 1 and the substrate 8 are simultaneously grooved by a dicing saw or the like (FIG. 4, FIG. The dotted line portion 8a of 5a) forms an actuator having a large number of acting portions. At the time of grooving, this grooving is performed so as not to groov up to the edge end of the substrate 8 on the common electrode side, and the grooving is stopped with the distance L left. When the groove is processed to the edge end, the common conductor pattern 9a on the substrate is formed.
Will be divided into a plurality of parts, and the function of the common electrode will not be fulfilled. Further, the processing depth H of the groove 8a is, of course, deeper than the thickness of the conductor patterns 9a and 9b on the substrate 8, but is set so that the strength of the substrate 8 is not extremely weakened or damaged. .

FIG. 6 is a view showing a case where the escape groove G for the adhesive is provided on the substrate 8. When the piezoelectric element 1 is bonded to the substrate 8 with the adhesive 10 as in the above embodiment, a conductive adhesive is used. Agent 1
There is a risk that 0 will protrude and the select electrode and the common electrode will short-circuit on the substrate 8. Therefore, if a groove G is provided on the substrate 8 as an escape area for the adhesive as shown in the figure, the above-mentioned short circuit can be prevented. You can

FIG. 7 is a sectional view for explaining the third embodiment of the present invention. In this embodiment, the piezoelectric element 1 and the substrate 8 are used.
According to this embodiment, since it is not necessary to make the substrate 8 larger than the piezoelectric element 1, the size of the substrate 8 is smaller than that of the second embodiment (FIG. 4). Can be made smaller.

8 (a) to 8 (e) are a plan view and a side view of the substrate 8 shown in FIG. 7, and FIG. 8 (a) shows a plan view, as indicated by a dotted line in the figure. The groove 8a is cut along the entire length of the substrate 8. As described above, when the groove processing is performed up to the edge end, the common electrode pattern 9a on the substrate 8 is divided into a plurality of parts, and each is in an insulated state. The common electrode 9a as shown in FIG. 8 (b) may be patterned, or the common electrode 9a may be patterned as shown in FIG. 8 (c) on the left side of the drawing. Alternatively, as shown in FIGS. 8D and 8E, using a conductive adhesive 9a on the side surface and the upper surface,
It may be electrically conducted.

[0026]

【The invention's effect】

Effect corresponding to claim 1: Since the electrode member of the piezoelectric element can be joined on the same plane as the external conductor pattern, the alignment is easy, and the electrodes can be joined at one time and mass-produced. Effect corresponding to claim 2: The selection electrode can be made higher in density by preliminarily solder-plating an external conductor pattern. In addition, the common electrode is a junction with the anisotropic conductive film that is unlikely to cause a short circuit with the selection electrode.
The bond has high reliability and high yield. Effect corresponding to claim 3: Since the joint member of the common electrode protrudes onto the slit at the time of joining, there is no protrusion in the direction of the laminated electrode of the piezoelectric element, and there is no risk of short circuit. Effect corresponding to claim 4: Since the conductor patterns of the selection electrode and the common electrode can be integrally formed, the cost can be reduced and the handling becomes easy. Effect corresponding to claim 5: Since damage and deterioration of the piezoelectric element due to groove machining are eliminated, reliability and yield are improved, and groove machining accuracy is rough, which is advantageous for mass production. Effect corresponding to claim 6: Since it is not necessary to interrupt the groove processing and there is no restriction on the bonding positional relationship between the piezoelectric element and the substrate,
The process is simplified and the range of utilization as an actuator is widened. Effect corresponding to claim 7: Since the FPC is solder-bonded on the substrate, the piezoelectric element is not affected by the heating and pressing steps, and the setting margin of the bonding condition can be widened. Effect corresponding to claim 8: By providing a groove on the substrate,
When the piezoelectric element and the substrate are joined together, a protrusion of the conductive adhesive is formed, and a short circuit due to the protrusion can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a first embodiment of the present invention.

FIG. 2 is a sectional view of the piezoelectric element 1 shown in FIG.

3 is a plan view of the FPC used in the example of FIG. 1 taken along the line III-III.

FIG. 4 is a sectional view for explaining a second embodiment of the present invention.

5 is a plan view of a substrate 8 and a FPC 4 used in the embodiment of FIG.

FIG. 6 is a cross-sectional view when a solder relief groove G is provided on the substrate.

FIG. 7 is a cross-sectional view for explaining a third embodiment of the present invention, that is, an embodiment when the groove processing is performed up to the edge end.

8 is a surface view of a main part of the substrate of the embodiment shown in FIG.

FIG. 9 is a sectional view and a partially enlarged sectional view of a conventional inkjet recording head.

FIG. 10 is an enlarged view of an essential part showing the connection of the piezoelectric element of the conventional inkjet recording head.

FIG. 11 is a plan view illustrating another example of a conventional inkjet recording head.

FIG. 12 is a perspective view showing a part of the manufacturing process of the conventional inkjet recording head.

13 is a perspective view showing a part of a step that is subsequent to the step shown in FIG.

FIG. 14 is a cross-sectional view (cross-sectional view taken along the line AA of FIG. 13) of the inkjet recording head shown in FIGS.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric element, 2a ... Internal common electrode, 2b ... Internal selection electrode, 3a ... External common electrode, 3b ... External selection electrode, 4 ... F
PC, 4a ... Common electrode pattern of outer conductor, 4b ... Selection electrode pattern of outer conductor, 4c ... Upper cover film, 4d
... Lower cover film, 6, 7 ... Solder, 8 ... Substrate, 8a
... groove, 9a ... common electrode pattern on substrate, 9b ... selection electrode pattern on substrate, 10 ... conductive adhesive, 11 ... substrate, 1
2 ... Piezoelectric element, 12a ... Non-driving piezoelectric element, 12b ... Driving piezoelectric element, 12c ... Both ends of piezoelectric element, 12d ... Common electrode, 12e ... Piezoelectric element electrode, 13 ... Flow path plate, 13a ... Ink flow path, 13b ... Wall part, 14 ... Common liquid chamber constituent member, 1
4a ... Common liquid chamber, 15 ... Ink supply pipe, 16 ... Nozzle plate, 16a ... Nozzle, 17 ... FPC, 18 ... Lead wire, 19 ... Drive electrode, 20 ... Groove, 21 ... Protective plate, 2
2 ... Fluid resistance, 23 ... Hot electrode, 24 ... Ground electrode, 25 ... Upper partition wall, 30 ... Upper electrode, 31 ... Piezoelectric element, 32 ... Soldering, 33 ... Dot electrode, 34 ... Common electrode, 35 ... Main body, 36 ... Lower electrode, 40 ... Substrate, 41
a to 41c ... Electrodes, 42 ... Piezoelectric elements, 43 ... Slits,
44 ... Driving IC.

Claims (8)

[Claims] 1. A plurality of channels for containing a recording liquid, a plurality of nozzles communicating with each of the channels, and a plurality of nozzles for discharging the recording liquid from the nozzles by changing the volume in the channels. In the ink jet recording head including the actuator, the actuator includes a substrate and a laminated piezoelectric element formed on the substrate, and the laminated piezoelectric element has a plurality of flow paths over the entire length in the longitudinal direction of the flow path. Inkjet recording characterized by being divided into a number of paths and configured to operate independently as actuators, and on the same plane, a selection electrode and a common electrode are respectively connected to an external conductor pattern. head. 2. The selection electrode and the selection electrode of the outer conductor pattern are joined by solder, and the common electrode and the common electrode of the outer conductor pattern are joined by an anisotropic conductive film. The inkjet recording head according to claim 1, wherein 3. A common pattern portion of the outer conductor pattern,
3. The ink jet recording head according to claim 1, wherein the ink jet recording head has a slit that intersects the longitudinal direction of the flow path. 4. The common electrode pattern of the outer conductor and the selection electrode pattern are integrally held by a film member.
The inkjet recording head described. 5. A laminated piezoelectric element having a common electrode area and a selection electrode area separated on the same surface, and a substrate having a common electrode area and a selection electrode area separated on the same surface, respectively. The selective electrode regions are bonded to each other so as to face each other, the laminated piezoelectric element is divided into a plurality of channels over the entire length in the longitudinal direction of the channel, and the electrodes in the selective electrode regions of the substrate are the laminated piezoelectric elements. An inkjet recording head characterized in that the electrodes in the common electrode region of the substrate are partially separated in the same manner as the laminated piezoelectric element, and are not separated on the edge side. 6. A laminated piezoelectric element having a common electrode area and a selection electrode area separated on the same surface, and a substrate having a common electrode area and a selection electrode area separated on the same surface, respectively. The selective electrode regions are bonded to each other so as to face each other, and the laminated piezoelectric element is divided into a plurality of flow channels over the entire length in the flow channel longitudinal direction, and electrodes of the select electrode region and the common electrode region of the substrate are also separated. An ink jet recording head, characterized in that it is separated in the same manner as the laminated piezoelectric element, and a conductor on the side surface of the common electrode region of the substrate is electrically connected to an electrode of the common electrode region on the substrate. 7. The ink jet recording according to claim 5, wherein conductor patterns are arranged in the vicinity of the edge on the side of the selective electrode on the substrate, and the conductor patterns are soldered to the outer conductor patterns. head. 8. The substrate is provided with a groove that intersects with the flow path direction, and the groove is a relief groove for a conductive adhesive that bonds the piezoelectric element and the substrate. The inkjet recording head according to claim 5, 6 or 7.