JP2002103601A - Ink jet print head and ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet print head and an ink jet printer in which the wirings each connecting a piezoelectric element electrically with its driving circuit can be prevented from touching each other. SOLUTION: A substrate 40 interposed between juxtaposed piezoelectric element 20 and its driving circuit 60 is provided with through grooves 44 passing a plurality of wirings 62 for connecting the piezoelectric element electrically with the driving circuit while extending from the arranging face side of the piezoelectric element to the arranging face side of the driving circuit. Protrusions and recesses are made at the edge part of the through groove at least on the driving circuit side. Since the wiring is placed in each recess made at the edge part of the through groove in the wire bonding process, the wire bonded wiring does not flex even if it is pushed by a resin in the resin sealing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet print head for ejecting ink droplets by driving displacement of a piezoelectric element and an ink jet printer for printing information on a recording medium using the head.

[0002]

2. Description of the Related Art In general, an ink jet type print head is connected to a nozzle opening, a pressure generating chamber which is communicated with the nozzle opening and a part of which is constituted by a diaphragm, and is connected to a diaphragm of the pressure generating chamber. The piezoelectric element is provided. In such a configuration, the piezoelectric element is driven and displaced to deform the diaphragm, and the ink in the pressure generating chamber is pressurized to discharge ink droplets from the nozzle openings.
The information is printed on a recording medium.

As the above-mentioned ink jet type print head, a type using a longitudinal vibration mode piezoelectric element which expands and contracts in the axial direction has been put to practical use. According to the ink jet print head of this type, the volume of the pressure generating chamber can be changed by bringing the end face of the piezoelectric element into contact with the vibration plate, so that the print head can be suitable for high-density printing. However, in the manufacturing process of disposing the piezoelectric element on the diaphragm, the piezoelectric element is cut into a comb shape in accordance with the arrangement pitch of the nozzle openings, and the cut and divided piezoelectric element is positioned and fixed in the pressure generating chamber. There is a problem that difficult work is required.

On the other hand, as another type of ink jet print head, a type using a flexural vibration mode piezoelectric element has been put to practical use. According to the ink jet print head of this system, the piezoelectric element can be disposed on the diaphragm by a relatively simple operation of merely sticking and firing a green sheet made of a piezoelectric material in accordance with the shape of the pressure generating chamber and firing the green sheet. Therefore, the above problem can be solved. However, since the flexural vibration is used, a certain area of the piezoelectric element is required, and there is a problem that high-density arrangement is difficult.

[0005] In order to solve this problem, there has been proposed an ink jet print head utilizing a film forming technique. That is, a piezoelectric material layer is formed uniformly over the entire surface of the vibration plate, and this piezoelectric material layer is cut into a shape corresponding to the pressure generation chambers by lithography, and the piezoelectric elements are formed independently for each pressure generation chamber. I do. According to this, the piezoelectric element can be disposed on the diaphragm by a precise and simple method called lithography, so that the work of attaching the piezoelectric element to the diaphragm becomes unnecessary, and the thickness of the piezoelectric element is further reduced. There is an advantage that high-speed driving becomes possible.

[0006]

By the way, in the ink jet print head utilizing the above-mentioned film forming technique, the electric connection between the piezoelectric element and its driving circuit is performed by wire bonding. However, in the resin sealing step performed after the wire bonding step, there is a possibility that a plurality of wire-bonded wirings are pressed by the resin and bend, and the wirings come into contact with each other. Then, when the wirings come into contact with each other, it is necessary to correct the bending of the wirings using a needle or the like before the resin hardens, which is very troublesome.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned various problems, and an object of the present invention is to prevent contact between wirings that electrically connect a piezoelectric element and a driving circuit thereof. It is an object of the present invention to provide an ink jet type print head and an ink jet type printer which can perform the above.

[0008]

According to an aspect of the present invention, there is provided an ink jet print head, comprising: a substrate disposed between a piezoelectric element and a driving circuit for the piezoelectric element; A substrate that penetrates from the piezoelectric element arrangement surface side to the drive circuit arrangement surface side and has a through groove formed therein through which a plurality of wirings electrically connect the piezoelectric element and the drive circuit. At least an edge of the through groove on the drive circuit side is formed in an uneven shape.

Thus, in the wire bonding step, each wiring enters each recess formed at the edge of the through groove, so that even if the wire bonded in the resin sealing step is pressed by the resin, the wiring is bent. It is possible to prevent the wires from contacting each other,
It is possible to omit the step of correcting the wiring deflection before the resin is hardened as in the related art. Therefore, the contact between the wirings can be completely eliminated, and the manufacturing cost can be reduced.

The invention according to claim 2 is characterized in that the concave portion formed in the edge portion is formed so that a pitch at which the concave portion is formed is substantially the same as an arrangement pitch of the wiring. Thus, since the pitch at which the recesses are formed substantially matches the pitch at which the wirings are arranged, it is possible to ensure that the wirings enter the recesses during wire bonding.

According to a third aspect of the present invention, the concave portion formed in the edge portion is formed such that a width in a forming pitch direction is equal to or less than an arrangement pitch of the wiring. As a result, the width of the concave portion in the forming pitch direction is made equal to or smaller than the arrangement pitch of the wiring, so that adjacent wiring does not enter one concave portion, and only one corresponding wiring always enters. Can be made.

The invention according to claim 4 is characterized in that the substrate is a silicon single crystal substrate having a plane orientation of (110). By using a silicon single crystal substrate having a plane orientation of (110), at least the edge of the through groove can be easily formed into an uneven shape when the through groove is formed by etching.

The invention according to claim 5 is characterized in that an insulating film is formed at least on the edge.
In the invention according to claim 6, the wiring is covered with an insulating film. As a result, leakage from the wiring can be reliably prevented.

According to a seventh aspect of the present invention, there is provided an ink jet print head according to any one of the first to sixth aspects, and information is printed on a recording medium using the head. By the above-described respective operations, it is possible to provide a good and inexpensive printer with no conduction failure.

[0015]

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

FIG. 1 is a perspective view showing a configuration example of an ink jet printer according to an embodiment of the present invention. This ink jet printer includes an ink jet print head 100 and a head driving mechanism 10 in a main body 101.
2. Auto sheet feeder (automatic continuous paper feed mechanism) 103
Is provided, and a tray 104 is provided at the upper rear of the main body 101.

Ink jet print head 100
Is provided with a total of four color ink cartridges 105, for example, yellow, magenta, cyan, and black, and is configured to be capable of full-color printing. The ink ejection timing of the inkjet print head 100 and the scanning of the head drive mechanism 102 are controlled by a dedicated controller board or the like built in the main body 101, and high-precision ink dot control, halftone processing, and the like are executed. It has become.

The recording paper 106 fed to the tray 104 is automatically sent out by the automatic sheet feeder 103 and is discharged from a paper discharge port 107 provided on the front of the main body 101. . As the recording paper 106, plain paper, special paper, recommended OHP sheet, glossy paper, glossy film, label sheet, postcard made by government, etc. can be used.

FIG. 2 is an exploded perspective view showing a schematic configuration example of the ink jet print head 100 of FIG. In this figure, only one color head is shown for convenience. In the ink jet type print head 100, a flow path forming substrate 30 in which the piezoelectric element 20 is formed on the nozzle plate 10 is joined, and a reservoir forming substrate 40 is joined on the flow path forming substrate 30 to form a reservoir. A sealing plate 50 and a drive circuit (driver IC) 60 for the piezoelectric element 20 are joined on the substrate 40, and these are covered with a case head 70.

FIG. 3 is a sectional view showing details when the ink jet print head 100 of FIG. 2 is assembled. In this figure, only the head for one color is shown for convenience. The nozzle plate 10 has a thickness of, for example, 0.1
It is made of glass ceramics or non-rust steel having a linear expansion coefficient of 2.5 to 4.5 (× 10 ⁻⁶ / ° C.) at a temperature of 300 ° C. or less, for example, at 300 ° C. or less. As shown in FIG. 3, the nozzle plate 10 has a plurality of nozzle openings 11 arranged in two rows.

The flow path forming substrate 30 has a thickness of, for example, 150
It is made of a silicon single crystal substrate having a thickness of from μm to 300 μm and a plane orientation of (110). As shown in FIG. 3, one surface of the flow path forming substrate 30 is formed as an opening surface, and an elastic film (not shown) made of silicon dioxide having a thickness of 1 μm to 2 μm and formed by thermal oxidation in advance is formed on the other surface. The piezoelectric element 20 is further formed as shown in FIG.

As shown in FIG. 3, pressure generating chambers 31 defined by a plurality of partition walls are arranged in the width direction on the opening surface of the flow path forming substrate 30 by anisotropic etching. As shown in FIG. 2 and FIG. 3, a communication part 32 that forms a part of a reservoir 80 that communicates with a reservoir part 41 of a reservoir forming substrate 40 to be described later and serves as a common ink chamber of each pressure generation chamber 31 is formed. Formed by anisotropic etching,
Each of the pressure generating chambers 31 is communicated with one longitudinal end thereof via an ink supply path 33. The ink supply path 33 is also partitioned by a partition wall, similarly to the pressure generating chamber 31.

As shown in FIG. 3, a nozzle opening 11 communicating with the pressure generating chamber 31 on the side opposite to the ink supply path 33 is formed on the opening side of the flow path forming substrate 30. The nozzle plate 10 is fixed via an adhesive or a heat welding film. For this reason, the nozzle plate 10
One of the surfaces also functions as a reinforcing plate that entirely covers one surface of the flow path forming substrate 30 and protects it from impact and external force. The nozzle plate 10 may be formed of a material having substantially the same thermal expansion coefficient as that of the flow path forming substrate 30. In this case, the deformation of the nozzle plate 10 and the flow path forming substrate 30 due to heat is substantially the same. It is possible to easily and reliably join using a thermosetting adhesive or the like.

On the other hand, as shown in FIGS. 2 and 3, a lower electrode film having a thickness of, for example, about 0.2 μm is formed on the elastic film on the side opposite to the opening surface of the flow path forming substrate 30. For example, about 1
A piezoelectric element 20 composed of a piezoelectric layer having a thickness of μm and an upper electrode film having a thickness of, for example, about 0.1 μm is laminated by a thin film forming process. Generally, one of the electrodes of the piezoelectric element 20 is used as a common electrode, and the other electrode and the piezoelectric layer are patterned for each of the pressure generating chambers 31. And
The lead electrode 21 extends from the vicinity of one longitudinal end of the upper electrode film of the piezoelectric element 20 to a region facing the peripheral wall of the pressure generating chamber 31.

The reservoir forming substrate 40 has a thickness of, for example, 1
It is made of a silicon single crystal substrate having a size of 50 μm to 300 μm and a plane orientation of (110). Thus, similarly to the case of the nozzle plate 10 described above, the flow path forming substrate 30 and the reservoir forming substrate 40 can be easily and reliably bonded using a thermosetting adhesive or the like.

As shown in FIGS. 2 and 3, the reservoir forming substrate 40 communicates with a portion of a reservoir 80 which serves as a common ink chamber for the pressure generating chambers 31 of the flow path forming substrate 30 described above. The reservoir section 41 communicating with the section 32 is arranged in the width direction by anisotropic etching. As shown in FIG. 3, an ink introduction path 42 communicating with an ink introduction port 51 of a sealing plate 50 described later is anisotropic. It is formed by reactive etching.

The piezoelectric element 2 of the reservoir forming substrate 40
In the area corresponding to 0, as shown in FIG.
A sealable space 43 is formed by anisotropic etching so as not to hinder the movement of zero, and a communication hole (not shown) for communicating the space 43 with the outside is provided by anisotropic etching. In addition, a drive circuit 60 and a wiring pattern 61 for the piezoelectric element 20 are provided on the surface opposite to the surface on which the space 43 is formed, as shown in FIGS.

The space 43 is filled with a drying fluid such as an inert gas through a communication hole and sealed. The inside of this space 43 is sealed at a pressure lower than the atmosphere,
Thus, the piezoelectric element 20 is securely sealed in the dry fluid atmosphere and is isolated from the external environment. As the drying fluid, a reducing gas can be used in addition to the inert gas. Conversely, by including an oxidizing gas, an environment for preventing the deterioration of the piezoelectric layer can be formed. . When such an inert gas is used, it is desirable to reduce the vapor pressure (partial pressure) of water therein as much as possible.

As shown in FIGS. 2 and 3, a drive circuit 60 is disposed between the reservoir 41 and the space 43 on the reservoir forming substrate 40 from the side where the piezoelectric element 20 is disposed.
And a plurality of wirings 6 that penetrate the lead electrode 21 of the piezoelectric element 20 and the drive circuit 60.
A through-groove 44 through which 2 passes is formed by anisotropic etching. As will be described later in detail, the inner wall surface of the through-groove 44 on the space 43 side, and at least the edge (corner) of the through-groove 44 on the drive circuit 60 side is formed in an uneven shape which is a characteristic part of the present invention. Have been.

The sealing plate 50 is made of, for example, a laminate of a PPS film and a stainless steel plate. This sealing plate 5
0 has a role of sealing the reservoir 80. Also,
As shown in FIG. 3, the ink introduction slot 51 communicating with the ink introduction path 42 of the reservoir forming substrate 40 is formed on the sealing plate 50 as described above. The case head 70 has a role of covering and protecting the above-described components, and forming a space for injecting the sealing resin 71 of the drive circuit 60 and the wiring 62 as shown in FIG.

FIG. 4 is a perspective view showing an outer shape of the reservoir forming substrate 40, and FIG. 5 is an enlarged view of a portion A in FIG. FIG.
The inner wall surface on the space 43 side of the through groove 44 shown in FIG.

The concave portion 44a in this example is formed such that its formation pitch P1 is substantially the same as the arrangement pitch P11 of the wiring 62 (see FIG. 6). Thus, the recess 44
6A and the arrangement pitch P11 of the wiring 62 are substantially matched, so that when the wiring 62 is wire-bonded as shown in FIGS.
Can be reliably inserted into each recess 44a.

The recess 44a is formed such that the width w1 in the direction of the formation pitch P1 is equal to or less than the arrangement pitch P11 of the wiring 62. As described above, the width w1 of the concave portion 44a in the direction of the formation pitch P1 is changed to the arrangement pitch P1 of the wiring 62.
As shown in FIG. 6 (A),
As shown in (B), when wire 62 is wire-bonded, adjacent wire 62 does not enter one recess 44a, and only one corresponding wire 62 can always enter.

As described above, the lead electrode 2 of the piezoelectric element 20
In the wire bonding step of the wiring 62 for electrically connecting the driving circuit 60 to the driving circuit 60, each wiring 62
, Respectively, so that the wires 62 bonded by wire in the sealing step of the sealing resin 71 do not bend even when pressed by the sealing resin 71. Therefore, the contact between the wirings 62 can be prevented, and the step of correcting the bending of the wiring before curing the resin as in the related art can be omitted. Therefore, the contact between the wirings can be completely eliminated, and the manufacturing cost can be reduced.

The recess 44a is formed on the entire inner wall surface of the through groove 44 on the space 43 side.
What is necessary is just to be able to hold the wiring 62, and it is sufficient to form it at least at the edge (corner) of the through groove 44 on the drive circuit 60 side. Further, the shape is not limited to a sine wave, and may be, for example, a pulse wave, a sawtooth wave, a triangular wave shape, or the like.

FIG. 7A is a plan view showing an example of a mask for forming the recess 44a in the reservoir forming substrate 40 by anisotropic etching. In the mask 1, the hatched portion is a masking portion, and the white portion is a through groove 44.
Is the part that forms The portion where the concave portion 44a is to be formed is formed in the shape of a sawtooth 1b having a portion 1a projecting obliquely.

Here, in the anisotropic etching, when a silicon single crystal substrate is immersed in an alkaline solution such as KOH, the substrate is gradually eroded and the first (111) plane perpendicular to the (110) plane and the first (111) plane Make an angle of about 70 ° with the (111) plane of
In addition, a second (111) plane that forms an angle of about 35 ° with the (110) plane appears. At this time, the etching rate of the (110) plane is about 10 times smaller than the etching rate of the (111) plane. This is performed using the property of 1/180.

By such anisotropic etching, precision processing is performed on the basis of depth processing of a parallelogram formed by two l- (111) planes and two oblique second (111) planes. be able to. When a groove or the like that does not penetrate is formed, the silicon single crystal substrate may be etched halfway in the thickness direction (half etching), and this control is performed by adjusting the etching time.

When such anisotropic etching is performed, as shown in FIG. 7 (B), the silicon single crystal substrate is firstly cut from the front end side of the portion covered by the obliquely protruding portion 1a of the mask 1. It is gradually etched (a to b in FIG. 7B).
b) When the portion covered by the obliquely protruding portion 1a disappears (c in FIG. 7B), the portion covered by the saw tooth 1b is gradually etched from the tip side (FIG. 7).
(B) d), finally, the concave portion 44a can be easily formed on the entire inner wall surface of the through groove 44 on the space 43 side (e in FIG. 7B).

FIG. 8 shows a portion A in FIG.
FIG. 10 is an enlarged view of another example of the inner wall surface on the space 43 side in FIG.
An edge (corner) on the drive circuit 60 side of the through groove 44 shown in FIG.

The concave portion 44b in this example is also formed such that the formation pitch P2 is substantially the same as the arrangement pitch P12 of the wiring 62 (see FIG. 9). Thus, the recess 44
Since the formation pitch P2 of the wiring b and the arrangement pitch P12 of the wiring 62 are substantially the same, as shown in FIGS.
Can be reliably inserted into each recess 44b.

The recess 44b is also formed such that its width w2 in the direction of the formation pitch P2 is equal to or less than the arrangement pitch P12 of the wiring 62. As described above, the width w2 of the concave portion 44b in the direction of the formation pitch P2 is determined by the arrangement pitch P1 of the wiring 62.
As shown in FIG. 9 (A),
As shown in (B), when wire 62 is wire-bonded, adjacent wire 62 does not enter one recess 44b, and only one corresponding wire 62 can always enter.

As described above, the lead electrode 2 of the piezoelectric element 20
In the wire bonding step of the wiring 62 for electrically connecting the driving circuit 60 to the driving circuit 60, each wiring 62
, Respectively, so that even if the wire 62 wire-bonded in the sealing step of the sealing resin 71 is pressed by the sealing resin 71, the wiring 62 does not bend. Therefore, the contact between the wirings 62 can be prevented, and the step of correcting the bending of the wiring before curing the resin as in the related art can be omitted. Therefore, the contact between the wirings can be completely eliminated, and the manufacturing cost can be reduced.

Although the recess 44b is formed in the shape of a prismatic groove, it is sufficient that the wire 62 can be held.
For example, it may be a pyramid, a hemisphere, a slit, or the like.

Here, in order to reliably prevent leakage from the wiring 62, the surface of the reservoir forming substrate 40 on the drive circuit 60 side, the inner wall surface of the through groove 44 on the drive circuit 60 side, or at least the edge portion, That is, the wiring 62
An insulating film is formed in a portion in contact with
May be coated with an insulating film.

As described above, the present invention has been described with respect to various embodiments. However, the present invention is not limited to the above embodiments, and other embodiments may be included within the scope of the invention described in the claims. It goes without saying that also applies.

[0047]

As described above, according to the ink jet print head and the ink jet printer according to the present invention, the wire-bonded wiring is pressed by the resin in the resin sealing step of the drive circuit portion of the print head. Also, the wires do not bend, so that contact between the wirings can be prevented. For this reason, it is possible to omit the conventional process of correcting the wiring deflection before the resin is cured. Therefore, the conduction failure can be completely eliminated, and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration example of an ink jet printer according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a schematic configuration example of the inkjet print head of FIG.

FIG. 3 is a sectional view showing details when the ink jet print head of FIG. 2 is assembled.

FIG. 4 is a perspective view showing an outer shape of a reservoir forming substrate of the ink jet print head of FIG. 2;

5 is an enlarged view of a portion A of the reservoir forming substrate of FIG. 4, that is, an inner wall surface on a space side in a through groove.

6A and 6B are a perspective view and a cross-sectional view illustrating a relationship between each wiring and each recess when wiring is wire-bonded to a through groove of the reservoir forming substrate of FIG. 5;

7A and 7B are a plan view showing an example of a mask for forming a concave portion on the reservoir forming substrate of FIG. 5 by anisotropic etching, and a diagram showing the progress of etching.

8 is another enlarged view of a portion A of the reservoir forming substrate of FIG. 4, that is, the inner wall surface on the space side in the through groove.

9 is a perspective view and a cross-sectional view illustrating a relationship between each wiring and each recess when wire bonding is performed to the through groove of the reservoir forming substrate of FIG. 8;

DESCRIPTION OF REFERENCE NUMERALS 1 mask 10 nozzle plate 11 nozzle opening 20 piezoelectric element 30 flow path forming substrate 31 pressure generating chamber 32 communication part 33 ink supply path 40 reservoir forming substrate 41 reservoir part 42 ink introduction path 43 space 44 through groove 44a recess 44b Recess 50 Sealing plate 51 Ink inlet 60 Drive circuit (driver IC) 70 Case head 71 Sealing resin 80 Reservoir 100 Inkjet printhead 101 Main body 102 Head drive mechanism 103 Auto sheet feeder (automatic continuous paper feed mechanism) 104 Tray 105 ink cartridge 106 recording paper 107 paper exit

Claims (7)

[Claims] 1. An ink-jet printhead for ejecting ink droplets by driving displacement of a piezoelectric element, wherein the substrate is disposed between the piezoelectric element and a driving circuit for the piezoelectric element. A substrate that penetrates from the surface side to the layout surface side of the drive circuit and has a through groove formed therein through which a plurality of wires that electrically connect the piezoelectric element and the drive circuit are provided; An ink jet print head, characterized in that at least an edge on the drive circuit side is formed in an uneven shape. 2. The ink-jet printing method according to claim 1, wherein the concave portions formed in the edge portion are formed so that a pitch at which the concave portions are formed is substantially equal to an arrangement pitch of the wiring. head. 3. The method according to claim 1, wherein the concave portion formed in the edge portion is formed such that a width in a forming pitch direction is equal to or less than an arrangement pitch of the wiring. Ink jet print head. 4. The ink jet print head according to claim 1, wherein the substrate is a silicon single crystal substrate having a plane orientation of (110). 5. The ink-jet printhead according to claim 1, wherein an insulating film is formed at least on the edge. 6. The ink jet print head according to claim 1, wherein the wiring is covered with an insulating film. 7. An ink jet printer comprising the ink jet print head according to claim 1, and printing information on a recording medium using the head.