JPH09277521A - Ink jet recording head and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multinozzle type ink jet recording head high in good product ratio and low in cost. SOLUTION: A solder layer 91 having a size covering all of ink pressure chambers 4 and extending to a common electrode attaching position is formed on the bonding surfaces of the piezoelectric elements 103 of the vibration plate 8 bonded to a passage substrate 1 having grooves becoming ink passages such as ink nozzles 2 or ink pressure chambers 4 to form ink passages and a piezoelectric element plate 100 having a size covering all of the ink pressure chambers 4 is soldered by this solder layer 91. Separation grooves 106 having a shape corresponding to that of the individual ink pressure chambers 4 are processed on the upper surface of the piezoelectric element plate 100 to form the signal electrodes of the piezoelectric elements 103 corresponding to the individual ink pressure chambers 4. The vibration plate 8 and the passage substrate 1 are bonded by a sheet adhesive 12.

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 used in an ink jet recording system in which ink is ejected as small droplets from a nozzle for recording, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A printing apparatus using an ink jet recording head is widely used in a field such as a desktop printer and a fax machine, which is required to be small and lightweight because of its simple structure. Although several methods have been proposed for an inkjet recording head, a method of adhering a piezoelectric element to a diaphragm and expanding and contracting the piezoelectric element by applying a voltage to the piezoelectric element to vibrate the diaphragm is an inkjet recording head. It has advantages such as a semi-permanent head life and low running cost, and is expected to be widely used in the future.

An ink jet recording head of this type (hereinafter abbreviated as a head) usually has an ink supply section, a fluid resistance adjusting section of a flow path, an ink pressurizing section, an ink ejection opening section, etc. on one surface thereof. The flow path substrate formed as a groove is joined to the sheet-like vibrating plate, and the piezoelectric element is bonded to the surface of the vibrating plate corresponding to the ink pressurizing portion. An ink flow path is formed by joining the flow path substrate and the vibrating plate, and the volume of the ink pressurizing unit changes due to the bimorph action of the vibrating plate and the piezoelectric element as the piezoelectric element expands and contracts, and the ink is ejected from the ink ejection port. Is ejected.

FIG. 6 shows a flow path arrangement of such a flow path substrate, and FIG. 7 is a sectional view along the flow path showing the structure of a head according to the prior art. An ink nozzle 2 serving as an ink ejection port is formed on a flow path substrate 1 made of a plastic plate, a glass plate, a metal plate, a silicon wafer, or the like by injection molding, etching, machining, or the like.
And a plurality of ink flow paths including the nozzle flow path 3, the ink pressurizing chamber 4 which is an ink pressurizing section, the ink supply path 5 and the throttle flow path 6 which is a fluid resistance adjusting section of the flow path, and the ink supply section. Grooves that will become ink reservoirs 7 are formed. On the groove side of the flow path substrate 1, a vibrating plate 8 made of glass and having a conductive layer 9 formed on a part of the surface thereof is laminated and joined by a sheet adhesive 12 to form an ink passage. There is. When the diaphragm 8 is made of metal, the conductive layer 9 is unnecessary. A piezoelectric element 10, which is an electromechanical conversion element, is bonded to the upper surface of the vibration plate 8 at a position corresponding to the ink pressurizing chamber 4 by an adhesive layer 11. As a method for joining the flow path substrate 1 and the diaphragm 8, in addition to adhesive joining, electrostatic joining, solvent joining, etc. are typical methods.

The piezoelectric element 10 of the head configured as described above
When a predetermined pulse voltage is applied to the upper electrode 101 and the lower electrode 102, the piezoelectric element 10 is deformed and the vibrating plate 8 is displaced to the ink pressurizing chamber 4 side by the bimorph action, and the volume of the ink pressurizing chamber 4 is increased. Rapidly decreases, the ink in the ink pressurizing chamber 4 is pressurized, and is ejected from the ink nozzle 2 through the nozzle flow path 3. The ejected ink becomes ink droplets and adheres to the recording paper to be printed.

[0006]

As described above, in the conventional method of manufacturing a head, when the piezoelectric element 10 is bonded to the vibration plate 8, a thermosetting adhesive is used. It is difficult to control because the adhesive is applied, and the upper electrode 101 is formed by the adhesive rising to the upper electrode 101.
Problems such as poor electrical continuity, voltage drop due to thick adhesive, and insufficient deformation of diaphragm due to insufficient adhesion, resulting in a decrease in the yield rate.

In the conventional head, the lower electrode 102 is used as a common electrode, the upper electrode 101 of the piezoelectric element 10 is used as an individual electrode, and the pad of the flexible printed board is pressure-bonded to the upper electrode 101. As a result, the displacement of the piezoelectric element 10 is constrained, which causes variation in ink ejection characteristics. An object of the present invention is to solve the above problems and to provide a low cost multi-nozzle head having a high yield rate.

[0008]

In order to solve the above-mentioned problems, according to the present invention, a piezoelectric element having electrodes formed on both surfaces is soldered to a diaphragm by a metallization layer formed on the diaphragm. Attached. Since the piezoelectric element is bonded to the diaphragm by soldering, conduction failure is eliminated.

Further, the solder layer for soldering is formed on the diaphragm by solder plating. Since it is formed by solder plating, its thickness can be controlled to the required minimum, so there is no defect such as rising of the solder to the upper electrode, and strong bonding with uniform thickness can be performed, so that the piezoelectric element deformation Can be efficiently transmitted to the diaphragm.

Further, the piezoelectric element mounting surface of the vibrating plate including at least a portion corresponding to all the ink pressurizing chambers has an area reaching at least all the ink pressurizing chambers, and electrodes are formed on both surfaces thereof. The piezoelectric plate is soldered, and the electrodes of the piezoelectric plate are separated on the front surface side of the piezoelectric plate by a separation groove into a shape corresponding to each pressurizing chamber. A piezoelectric plate extending over all the ink pressurizing chambers of the head is soldered, and the surface electrode of the piezoelectric plate is separated by the separation groove, whereby the same function as that of each piezoelectric element is exhibited. Also in this case, it is effective to form the solder layer by solder plating.

Further, the vibrating plate is made of an insulating material, and a metallized layer is formed in a separated state on each part of the surface of the vibrating plate corresponding to each pressurizing chamber, and at least all of the metallized parts are formed in this metallized part. The piezoelectric plate has an area extending to the ink pressurizing chamber, electrodes are formed on both sides thereof, and electrodes on the surface to be soldered to the vibration plate are separated corresponding to the individual ink pressurizing chambers. Is soldered. In this case, since the lower electrode is separated, the piezoelectric plate exhibits the same function as that of each piezoelectric element. In this case, since the lower electrode is an individual electrode, it is not necessary to take a signal electrode from the upper electrode of each piezoelectric element, and no mechanical external force is applied to the piezoelectric element. In this case, in order to make the separation more complete, the electrodes on the surface side of the piezoelectric plate are applied with ink while keeping the portions corresponding to all the ink pressurizing chambers electrically connected to each other. It is effective to separate at least three sides of the shape corresponding to the pressure chamber by the separation groove. Even in this case, it is effective to form the solder layer by solder plating.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A first point of the present invention is to join a piezoelectric element and a vibration plate by soldering, and a second point is that the piezoelectric element is not an individual element, A single piezoelectric plate covering the ink pressurizing chamber of
The piezoelectric element corresponding to each ink pressurizing chamber is formed by the separation groove formed on the piezoelectric plate or the separate metallization layer formed on the vibration plate. The third point is that soldering is performed on the solder plating layer. It is carried out by.

Examples will be described below.

[0014]

【Example】

(First Embodiment) FIG. 1 shows a first embodiment of the head according to the present invention.
2 is a sectional view showing the structure of the embodiment of FIG. FIG. 1 is a cross section taken along the line AA of FIG. Flow path substrate 1
Is made of an amorphous thermoplastic resin which is a plastic material, and is produced by injection molding. In the channel substrate 1, ink nozzles 2, nozzle channels 3, ink pressurizing chambers 4,
Grooves corresponding to the ink supply passage 5, the throttle passage 6 and the ink reservoir 7 are formed. The vibrating plate 8 is a nickel plate having a thickness of 30 μm, and a solder layer 91 having a thickness of 1 to 3 μm is formed on one surface of the vibrating plate 8 including at least a portion extending to the ink pressurizing chamber 4 and a portion extending to the common electrode mounting position 92. Are formed. This solder layer 91 was formed by electrolytic plating under the following conditions.

[0015] As shown in FIG. 2, the ink pressurizing chambers 4 of the flow path substrate 1 are regularly arranged vertically and horizontally. Corresponding to the regularly arranged ink pressurizing chambers 4, a solder layer 91 is formed on the piezoelectric element bonding surface side of the vibration plate 8 so as to cover all the ink pressurizing chambers 4. On the solder layer 91, a piezoelectric plate 100 having a size of covering the entire ink pressurizing chamber 4 and having an upper electrode 104 and a lower electrode 105 and a thickness of 50 μm is formed.
Was placed, heated, and heated to about 300 ° C. with a hot air gun, and the piezoelectric plate 100 and the vibration plate 8 were soldered.

Subsequently, the vibrating plate 8 to which the piezoelectric plate 100 is soldered and the plastic flow path substrate 1 are attached with a sheet adhesive.
Bonding was performed at 12 to form an ink flow path. After joining the vibrating plate 8 and the flow path substrate 1, the separation groove 106 shown in FIGS. 1 and 2 is formed on the piezoelectric plate 100 on the upper electrode 104 side according to the shape of the ink pressurizing chamber 4 by a dicing machine. Formed.
In this embodiment, the separation groove 106 has a width of 0.2 mm and a depth of 50 μm.
m. As in the prior art, the pads of the flexible printed board are soldered to the individual upper electrodes 104,
A head was manufactured.

The upper electrode 104 was used as a signal electrode, and a driving voltage of an appropriate waveform was applied between the upper electrode 104 and the common electrode of the solder layer 91 to perform a printing test. As a result, good printing characteristics were obtained. In this way, the piezoelectric plate over the entire large number of ink pressurizing chambers 4
By soldering 100 with a solder layer 91 having a thickness of 1 to 3 μm, conduction failure and sticking of the adhesive to the upper electrode were eliminated, and the yield rate was improved. In addition, the voids in the bonding layer did not occur, and the expansion and contraction of the piezoelectric element 103 were efficiently transmitted to the ink in the vibration plate 8 and the ink pressurizing chamber 4, and good ink ejection characteristics could be obtained.

(Second Embodiment) FIG. 3 is a plan view of a head according to a second embodiment of the present invention as viewed from the surface of a vibration plate before mounting a piezoelectric element, and FIG. 4 is a second embodiment. FIG. In this embodiment, the diaphragm 8 is a plate made of zirconia, which is an insulator, and has a thickness of 50 μm. As shown in FIG. 3, on the surface of the vibrating plate 8 on which the piezoelectric element is mounted, one to three pieces are provided in the lengthwise direction corresponding to each ink pressurizing chamber 4.
Separated copper electrodes 93 extending by mm were formed by sputtering, and a solder layer 94 was formed on the copper electrodes 93 by electrolytic plating in the same manner as in Example 1 using the copper electrodes 93 as a cathode.

On the other hand, as the piezoelectric element, a piezoelectric plate 100 having the same size as that of the first embodiment, which covers the entire ink pressurizing chamber 4 and has the upper electrode 107 and the lower electrode, is used. In the piezoelectric plate 100, a separation groove was formed in a shape corresponding to the ink pressurizing chamber in the electrode (lower electrode) on the side to be joined to the vibration plate 8 as in the case of FIG. The groove width in this case is wider than that in the first embodiment. This is to prevent the separation groove from being short-circuited by solder.

The vibration plate 8 having the solder layer 94 and the piezoelectric plate 100 having a separation groove on the surface on the soldering side are soldered in the same manner as in the first embodiment, and the vibration plate 8 having the piezoelectric plate 100 mounted thereon is mounted.
Was bonded to the flow path substrate 1 with the sheet adhesive 12 in the same manner as in Example 1 to form an ink flow path. In this embodiment, the individually separated solder layers 94 on the vibration plate 8 serve as signal electrodes corresponding to the individual ink pressurizing chambers 4, and the solder layer portion outside the piezoelectric plate 100 is attached to the flexible printed board. It is position 95, and the pad of the flexible printed board is soldered here. The upper electrode 107 of the piezoelectric plate 100 is a common electrode, and a portion where external force is not applied to the piezoelectric body corresponding to each ink pressurizing chamber 4 is set as a common electrode mounting position 109. A flexible printed board is soldered here and the head is attached. It was made.

In the head thus manufactured,
As a result of performing a printing test by applying a drive voltage having an appropriate waveform between the upper electrode 107 serving as the common electrode and the solder layer 94 serving as the signal electrode, good printing characteristics were obtained.
In this embodiment, the insulator is the vibrating plate 8 and the individual electrode for each ink pressurizing chamber 4 formed on the vibrating plate 8 is the signal electrode, so that the upper electrode 107 of the piezoelectric plate 100 is the common electrode. It was possible to reduce the influence of external force on the piezoelectric element, and it was possible to expand and stabilize the displacement due to expansion and contraction of the piezoelectric element.

In this embodiment, zirconia was used as the insulating material and a copper sputtered film was used as the metallizing layer. However, glass or other ceramics can be used as the insulating material, and nickel or the like can be used as the metallizing layer. It is also possible to adopt another metal or a film formed by another film forming method such as vapor deposition. (Third Embodiment) FIG. 5 is a plan view showing a third embodiment.

This embodiment is different from the second embodiment in that the upper electrode 107 of the piezoelectric plate 100 also has a function as a common electrode and corresponds to the ink pressurizing chamber 4.
That is, the separation groove 108 is formed. In the case of FIG.
The separation groove 108 is formed on the other three sides, leaving only one side on the center side. By the separation groove 108, the influence on the adjacent ink pressurizing chamber was further reduced, and more excellent ink ejection characteristics could be obtained.

[0024]

According to the present invention, since the piezoelectric element or the piezoelectric plate (hereinafter, represented by the piezoelectric element) is soldered to the vibration plate, the conduction failure due to the joining is eliminated, and the adhesive is used. A predetermined voltage can be applied to the piezoelectric element without a voltage drop, and the necessary deformation of the piezoelectric element can be secured.

Further, since the solder plating layer, which is sufficiently thinner than the thickness of the piezoelectric element, is used, a defect in which the solder sticks to the upper electrode does not occur. Further, since the vibrating plate and the piezoelectric element are firmly joined by solder, the deformation of the piezoelectric element can be efficiently transmitted to the vibrating plate, and the pad of the flexible printed board is also firmly fixed by soldering. Improves reliability.

Further, the piezoelectric element is a single piezoelectric plate extending over all the ink pressurizing chambers, the upper electrode thereof is separated by a separating groove, and the piezoelectric element corresponding to each ink pressurizing chamber is formed. Since the position of each piezoelectric element can be determined by, the man-hours for joining the piezoelectric elements can be reduced, and at the same time, the positioning accuracy can be significantly eased. If the piezoelectric element is a single piezoelectric plate that covers all the ink pressurizing chambers, the vibrating plate is an insulator, and the individual electrodes corresponding to each ink pressurizing chamber are formed on the vibrating plate, the upper electrode of the piezoelectric plate is Since it is a common electrode, it is not necessary to connect a signal electrode to the upper electrode of each piezoelectric element, the external force applied to the piezoelectric element can be reduced, and the displacement of the diaphragm can be expanded and stabilized.

As described above, according to the present invention, it is possible to provide a multi-nozzle head having a high yield rate, high reliability, and low cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a first embodiment of a head according to the present invention.

FIG. 2 is a plan view showing a first embodiment.

FIG. 3 is a plan view seen from a diaphragm surface before mounting a piezoelectric element in the second embodiment.

FIG. 4 is a plan view showing a second embodiment.

FIG. 5 is a plan view showing a third embodiment.

FIG. 6 is a plan view showing channels of a channel substrate.

FIG. 7 is a cross-sectional view showing the structure of a head according to the prior art.

[Explanation of symbols]

 1 flow path substrate 5 ink supply path 2 ink nozzle 6 throttle flow path 3 nozzle flow path 7 ink reservoir 4 ink pressurizing chamber 8 vibrating plate 9 conductive layer 91, 94 solder layer 93 copper electrode 92 common electrode mounting position 95 flexible printed board Mounting position 10, 103 Piezoelectric element 100 Piezoelectric plate 101, 104, 107 Upper electrode 102, 105 Lower electrode 106, 108 Separation groove 109 Common electrode mounting position 11 Adhesive layer 12 Sheet adhesive

Claims (5)

[Claims] 1. A flow path substrate having a groove for forming an ink flow path including an ink pressurizing chamber and a vibration plate are laminated and integrated.
In an ink jet recording head in which a piezoelectric element is mounted on the surface of the vibrating plate opposite to the flow path substrate, at a position corresponding to the ink pressurizing chamber, electrodes are formed on both surfaces of the piezoelectric element. An inkjet recording head characterized in that a piezoelectric element is soldered by an electrode on the diaphragm side and a metallized layer formed on the diaphragm. 2. The ink jet recording head according to claim 1, including at least a portion corresponding to all ink pressurizing chambers.
The piezoelectric element mounting surface of the vibrating plate is soldered with a piezoelectric plate having an area covering at least the entire ink pressurizing chamber, and electrodes are formed on both surfaces of the piezoelectric plate. An inkjet recording head characterized in that the electrodes of the plate are separated by a separation groove into a shape corresponding to each pressurizing chamber. 3. The ink jet recording head according to claim 1, wherein the vibrating plate is made of an insulating material, and portions of the surface of the vibrating plate that correspond to the individual pressure chambers are metallized in separate states. The metallized part has an area that covers at least the entire ink pressurizing chamber, and electrodes are formed on both surfaces of the metallizing part. The electrodes on the surface soldered to the diaphragm correspond to the individual ink pressurizing chambers. The inkjet recording head is characterized in that the piezoelectric plates separated by the above are soldered. 4. The ink jet recording head according to claim 3, wherein the electrodes on the front surface side of the piezoelectric body plate are electrically connected to each other in the portions corresponding to all the ink pressurizing chambers. An inkjet recording head characterized in that at least three sides of a shape corresponding to an ink pressurizing chamber are separated by separation grooves. 5. The method for manufacturing an ink jet recording head according to claim 1, wherein the piezoelectric element or the piezoelectric plate is soldered at a soldering position of a diaphragm to which the piezoelectric plate is soldered. A method for manufacturing an ink jet recording head, characterized in that a solder plating layer is provided in front, and the piezoelectric element or the piezoelectric plate and the vibration plate are soldered by the solder plating layer.