JP3867062B2 - Inkjet recording head - Google Patents

Description

[0001]
[Field of the Invention]
The present invention is an ink jet type in which one surface of a pressure generating chamber is sealed with a diaphragm, and the diaphragm is expanded and contracted by a piezoelectric vibrator in a longitudinal vibration mode to generate ink droplets from a nozzle opening. The present invention relates to a recording head.
[0002]
[Prior art]
For example, when a longitudinal vibration mode piezoelectric vibrator as disclosed in Patent Document 1 is used for driving an ink jet recording head, the contact area between the piezoelectric vibrator and the diaphragm can be made extremely small, so that 180 DPI per unit is obtained. The above resolution can be realized.
[0003]
In the longitudinal vibration mode piezoelectric vibrator A, as shown in FIG. 8, the internal electrode B which is one pole and the internal electrode C which is the other pole are laminated in a sandwich shape via the piezoelectric material D. The internal electrode B is exposed to the front end side, and the other internal electrode C is exposed to the rear end side, and each end face has a piezoelectric constant d31 connected to the segment electrode E and the common electrode F. The segment electrode E and the common electrode F are connected to the conductive pattern of the flexible cable H to supply a signal from an external drive circuit.
[Patent Document 1]
JP-A-5-104715 [0004]
[Problems to be solved by the invention]
The common electrode F formed on the rear end side has a drive current for all the piezoelectric vibrators A. Therefore, the upper surface, the rear end face, and the rear face of the piezoelectric vibrator A are used for the purpose of making the resistance as small as possible. The conductive layers F1 to F3 are formed on the three surfaces, and are divided into comb teeth so as to leave a part of the rear end side, thereby ensuring a conductive path. Reference symbol J in the drawing indicates a flow path unit that discharges ink droplets when the ink is pressurized by the piezoelectric vibrator A.
For this reason, electrode layers for external connection are required on the four surfaces of the front end surface, the rear end surface, and the front and back surfaces of the piezoelectric vibrator A, and these external electrode layers provide corrosion resistance to ink and ease of soldering. Gold is used to secure it. For this reason, if an attempt is made to form a thick electrode layer in order to reduce the resistance of the electrode layer in order to enable high-speed driving, there is a problem that the cost for forming the electrode is high.
The present invention has been made in view of such problems, and the object of the present invention is to use two electrode layers for external connection as two surfaces, while reducing the usage fee for expensive electrode materials. An object of the present invention is to provide an ink jet recording head capable of obtaining the same effect as that formed.
[0005]
[Means for Solving the Problems]
In order to solve such a problem, in the present invention, the internal electrodes of two poles extending in the displacement axis direction are alternately stacked with the piezoelectric material interposed therebetween, and the internal electrode serving as one pole extends to the tip surface, The plurality of piezoelectric vibrators having the piezoelectric constant d31 with the internal electrode serving as the other pole extending to the rear end face are fixed to the fixed substrate on the rear end side, and the tip face of the piezoelectric vibrator is used as the pressure generating chamber. An ink jet which is brought into contact with an elastic plate constituting a part of the nozzle, supplies a drive signal to each of the piezoelectric vibrators by a flexible cable, expands and contracts the volume of the pressure generating chamber, and ejects ink droplets from the nozzle openings In the recording head, at least the fixed surface of the piezoelectric vibrator of the fixed substrate has conductivity, and the tip surface of the piezoelectric vibrator and the surface not bonded to the fixed substrate A segment electrode that is electrically independent from the adjacent piezoelectric vibrator and connected to the flexible cable is formed, and from a surface that is not bonded to the fixed substrate at a certain distance from the segment electrode. A common electrode is formed to extend to the rear end face of the piezoelectric vibrator and to an area where the area facing the fixed substrate is in contact with the fixed substrate, and the increased area of the common electrode is the thickness of the common electrode. A conductive relationship is formed with the surface of the fixed substrate, and the common electrode is connected to be continuous on the rear end surface side due to the conductivity of the surface of the fixed substrate.
[0006]
[Action]
Since the thickened area at one end of the common electrode of the piezoelectric vibrator is connected in parallel to the conductive fixed substrate to reduce the electrical resistance, the common electrode formed on the piezoelectric vibrator has only two faces and is formed on three faces. It is possible to connect with low resistance equivalent to that.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show an embodiment of an ink jet recording head according to the present invention. A flow path unit 1 is connected to a nozzle plate 3 having nozzle openings 2 formed at a constant pitch, and to the nozzle openings 2. The pressure generating chamber 4 and the flow path forming substrate 7 having the reservoir 6 for supplying ink to the pressure generating chamber 4 through the ink supply port 5, and the tip of each piezoelectric vibrator 9 in the longitudinal vibration mode of the piezoelectric vibration unit 8. Thus, an elastic plate 10 for expanding and reducing the volume of the pressure generating chamber 4 is integrally laminated.
[0008]
The flow path unit 1 is connected to an opening surface 12 of a holder 11 constituted by injection molding of a polymer material, and the piezoelectric vibration unit 8 is connected to a flexible cable 13 for transmitting a driving signal from the outside, and then accommodated in a storage chamber. 14, the contact surface with each holder 11 is fixed with an adhesive, and a frame 15 serving also as a shield material is inserted into the nozzle plate side to constitute a recording head.
[0009]
The piezoelectric vibrator 9 in the longitudinal vibration mode includes an internal electrode 21 serving as one pole extending from the front end side to the front of the fixed region with the fixed substrate 16, and an internal electrode 22 serving as the other pole extending from the vicinity of the front end to the rear end. Are laminated in a sandwich shape via a piezoelectric material 23, and one internal electrode 21 is exposed at the front end side, and the other internal electrode 22 is exposed at the rear end side, so that the piezoelectric constant d31 is obtained.
[0010]
One internal electrode 21 is a segment electrode 24 formed with a conductive layer from the front end surface to the vicinity of the center of the piezoelectric vibrator 9, and the other internal electrode 22 is a central portion of the piezoelectric vibrator 9 from the rear end face. In addition, it is connected to a common electrode 26 formed by forming a conductive layer so as to have a certain distance 25 from the rear end side of the segment electrode 24.
[0011]
On the other hand, the fixed substrate 16 is formed by forming a metal layer on the surface of a conductive material such as non-rust steel or ceramics, and the piezoelectric vibrator 9 is made to coincide with the arrangement pitch of the pressure generating chambers 4 on this surface. In addition to being fixed, the piezoelectric vibrator 9 is conductively connected to a conductive surface 26b formed with an increased thickness so as to go around from the rear end surface 26a of the common electrode 26 to the fixed substrate 16 side.
[0012]
Then, at least one end side of the row of the piezoelectric vibrators 9 is configured in the same manner as the piezoelectric vibrator 9 as shown in FIGS. 3 and 4, that is, extends from the front end side to the front of the fixing region with the fixed substrate 16. An internal electrode 21 serving as one pole and an internal electrode 22 serving as the other pole extending from the vicinity of the front end to the rear end are laminated in a sandwich shape via the piezoelectric material 23, and the one internal electrode 21 is stacked on the front end side. The other internal electrode 22 is exposed at the rear end side, and the internal electrode 21 is further formed into a segment electrode 24 formed with a conductive layer from the front end surface to the vicinity of the center of the piezoelectric vibrator 9, and the other internal electrode 22 is Connected from the rear end surface to a common electrode 26 formed with a conductive layer so as to have a constant distance 25 from the rear end side of the segment electrode 24 at the center of the piezoelectric vibrator 9, and slightly more than the piezoelectric vibrator 9 Widely formed dami The piezoelectric vibrator 9 'is fixed.
[0013]
The segment electrode 24 and the common electrode 26 of each piezoelectric vibrator 9 of the vibrator unit 8 are connected to the conductive pattern of the flexible cable 13 via solder layers 28 and 29.
[0014]
As shown in FIG. 5, the flexible cable 13 includes ground conductive patterns 31 and 31 that match the widths of the dummy piezoelectric vibrators 9 ′ and 9 ′ at both ends of the vibrator unit 8, and the piezoelectric vibrators 9 and 9. , 9... Are formed on the base material 33 by providing conductive patterns 32, 32, 32,... For supplying drive signals corresponding to the segment electrodes 24.
[0015]
In this embodiment, when a drive signal is supplied from the external drive circuit via the flexible cable 13, the piezoelectric vibrator 9 that should eject ink droplets is connected to one of the conductive patterns 32 and the segment electrode 24 of the flexible cable 13. The drive signal is received by the internal electrode 21 which is a pole, and by the internal electrode 22 which is the other pole via the grounding conductive pattern 31, the fixed substrate 16 and the common electrode 26, and is displaced from the nozzle opening 2 by displacement due to the piezoelectric constant d31. Ink droplets are ejected.
[0016]
As described above, each piezoelectric vibrator 9 has a small common electrode 26 in contact with the fixed substrate 16 and connected in parallel by the conductive surface 26b formed by increasing the thickness of the opposing surface of the fixed substrate 16. The resistor is connected to the ground conductive pattern 31 of the flexible cable 16.
[0017]
Next, a manufacturing method of the above-described piezoelectric vibrator unit 8 will be described with reference to FIGS. While sandwiching the piezoelectric material 43, a conductive material 41 serving as an internal electrode serving as one pole extending from the front end to the terminal end of the active region and a conductive material serving as an internal electrode serving as the other pole extending from the rear end to the vicinity of the front end. Two piezoelectric diaphragms 44, 44 formed by laminating and baking after drying are prepared (FIG. 6 (I)).
[0018]
The piezoelectric diaphragms 44 and 44 are opposed to each other with two spacers 45 and 45 interposed therebetween so as to form an interval L that allows the external connection electrode forming material to slightly wrap around during deposition. The mask material 46, 46 is fixed to the boundary region between the segment electrode and the common electrode on the exposed front surface and back surface of 44 (FIG. 6 (II)), and the electrode forming material for external connection is deposited on the entire circumference. Electrode layers 47 and 48 are formed. In the process of vapor deposition, the external connection electrode forming material slightly wraps around as much as there is an interval L between the two piezoelectric diaphragms 44, 44, and slightly from the planes 44a, 44a of the piezoelectric diaphragms 44, 44. Exposed layers 47a and 48a are formed (FIG. 6 (III)).
[0019]
When the two piezoelectric diaphragms 44 and 44 are separated and the mask materials 46 and 46 are removed at the stage where the vapor deposition is completed, the front end surface, one surface, the rear end surface, and the opposed surface side are projected slightly. Two piezoelectric diaphragms 50 and 50 having conductive layers 47 and 48 formed only on three surfaces can be obtained (FIG. 6 (IV)).
[0020]
The region where only the other internal electrode 52 is formed, that is, the inactive region is positioned by positioning the metal or the fixed substrate 53 having the conductive layer formed on the fixed surface (FIG. 7 (I)). The layer 48a exposed from the end surface to the opposite surface is fixed with an adhesive so as to come into contact with the fixed substrate 53.
[0021]
Next, slits 56, 56, 56,... Are formed by a dicing saw or wire saw cutting tool 55 from the free end to at least the conductive layer 47 serving as the segment electrode and the rear end of the conductive material 41. When the vibration region as the child 9 and the region to be the segment electrode are cut into comb teeth, the piezoelectric vibrator unit is completed.
[0022]
When forming the slits 56, 56, 56,..., Both end portions are cut out slightly wide to form dummy piezoelectric vibrators 9 ′ and 9 ′ that are slightly wide and do not participate in vibration, and the conductive layer 48 is continuously formed. Leaving it in this state helps to lower the electrical resistance of the common electrode.
[0023]
【The invention's effect】
As described above, according to the present invention, the common electrode of the piezoelectric vibrator can be connected in parallel to the fixed substrate in the thickened region to reduce the electrical resistance, and the common electrode formed on the piezoelectric vibrator can be substantially formed. The effect equivalent to that formed on the three surfaces can be obtained while reducing the cost by reducing the area for forming the external connection electrodes only on the two surfaces.
[Brief description of the drawings]
FIG. 1 is an assembled perspective view showing an embodiment of an ink jet recording head of the present invention.
FIG. 2 is a view showing a cross-sectional structure of the apparatus.
FIG. 3 is a cross-sectional view showing a connection structure between a dummy piezoelectric vibrator and a flexible cable of the recording head.
FIGS. 4A and 4B are perspective views showing an embodiment of a piezoelectric vibration unit used in the recording head. FIG.
FIG. 5 is a diagram showing an example of a flexible cable.
FIGS. 6 (I) to (IV) are diagrams showing an electrode forming process in the manufacturing process of the vibrator unit used for the recording head.
FIGS. 7 (I) to (III) are diagrams showing up to the dividing step in the manufacturing process of the vibrator unit used in the recording head.
FIG. 8 is a cross-sectional view showing an example of a conventional ink jet recording head using a piezoelectric vibrator having a piezoelectric constant d31.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Flow path unit 8 Vibrator unit 9 Piezoelectric vibrator 9 'Dummy piezoelectric vibrator 13 Flexible cable 16 Fixed substrate 25 Segment electrode 26 Common electrode 26b Conductive surface formed by increasing the end face of the common electrode

Claims (10)

Internal electrodes of two poles extending in the displacement axis direction are alternately stacked with a piezoelectric material in between, the internal electrode serving as one pole extends to the front end surface, and the internal electrode serving as the other pole extends to the rear end surface. A plurality of piezoelectric vibrators having a piezoelectric constant d31 are fixed to the fixed substrate at the rear end side, and the tip end face of the piezoelectric vibrator is brought into contact with an elastic plate constituting a part of the pressure generating chamber. In an ink jet recording head that supplies a drive signal to each of the piezoelectric vibrators by a cable to expand and contract the volume of the pressure generating chamber to eject ink droplets from a nozzle opening,
The fixed surface of at least the piezoelectric vibrator of the fixed substrate has conductivity, and the piezoelectric vibrator adjacent to the tip surface of the piezoelectric vibrator and the surface not bonded to the fixed substrate, A segment electrode that is electrically independent and connected to the flexible cable is formed, and the rear surface of the piezoelectric vibrator is separated from the surface that is not bonded to the fixed substrate at a certain distance from the segment electrode. A common electrode extending to an end surface and thickened to such an extent that a region facing the fixed substrate can contact the fixed substrate is formed, and the thickened region of the common electrode is electrically conductive with the surface of the fixed substrate. An ink jet recording head in which the common electrode is continuously connected on the rear end surface side by the conductivity of the surface of the fixed substrate. Internal electrodes of two poles extending in the displacement axis direction are alternately stacked with a piezoelectric material interposed therebetween, and the internal electrode serving as one pole is exposed on the front end surface, and the internal electrode serving as the other pole is disposed on the rear end surface. A plurality of piezoelectric vibrators exposed and having a piezoelectric constant d31 are fixed at their rear ends to a fixed substrate, and the tip surfaces of the piezoelectric vibrators are brought into contact with an elastic plate constituting a part of the pressure generating chamber. In an ink jet recording head that supplies a drive signal to each of the piezoelectric vibrators by a flexible cable to expand and contract the volume of the pressure generating chamber to eject ink droplets from a nozzle opening,
At least a fixed surface of the piezoelectric vibrator of the fixed substrate has conductivity, and is connected to the flexible cable on the tip surface of the piezoelectric vibrator and a surface not bonded to the fixed substrate. A slit is formed from the front end side of the free end side so that the segment electrode is electrically independent of the adjacent piezoelectric vibrator, and the rear end side of the slit is continuous with the rear end side of the common electrode. A conductive layer extending from the surface not bonded to the fixed substrate at a certain distance from the segment electrode to the rear end surface of the piezoelectric vibrator is formed to be continuous between the adjacent piezoelectric elements; A conductive layer that is thick enough to be in contact with the fixed substrate in a region that is continuous with the conductive layer and that faces the fixed substrate is formed, and the thickened region of the common electrode is a surface of the fixed substrate. Ink jet recording head by forming a conductive relationship are connected by the conductive surface of the fixed substrate and.   The ink jet recording head according to claim 1, wherein the thickened region is formed by a wraparound phenomenon when the common electrode is formed by a film forming technique.   The ink jet recording head according to claim 1, wherein the fixed surface of the piezoelectric vibrator is an inactive region.   The ink jet recording head according to claim 1, wherein the fixed substrate and the piezoelectric vibrator are fixed with a conductive adhesive.   The ink jet recording head according to claim 1, wherein the fixed substrate is made of rust-proof steel.   The ink jet recording head according to claim 1, wherein the fixed substrate is configured by forming a metal layer on a ceramic surface.   The ink jet recording head according to claim 1, wherein the piezoelectric vibrator has at least a region where a segment electrode is formed separated by a slit.   The ink jet recording head according to claim 1, wherein the piezoelectric vibrator has a region where at least a part of the common electrode of the piezoelectric vibrator is not separated by a slit.   A conductive layer to which a conductive pattern for grounding the flexible cable is bonded to at least one end side of the fixed substrate in an arrangement direction of the plurality of piezoelectric vibrators and in a region where the piezoelectric vibrators are not present. Item 3. The ink jet recording head according to Item 1 or 2.

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