JPH07156397A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To make an oscillation plate a common electrode for driving a piezoelectric element by making a free edge face of the piezoelectric element a common electrode, and by making an oscillation plate transferring a displacement of the piezoelectric element 2 to a liquid room an electrically conductive metal plate and by connecting electrically the common electrode and the oscillation plate. CONSTITUTION:A piezoelectric element 2 responding to a nozzle 6, and a metal oscillation plate 4 transferring a displacement of the piezoelectric element 2 to a liquid room are possessed and a recording is executed by injecting ink from the nozzle 6a through a driving pulse signal to the piezoelectric element 2. A common electrode 9 for driving the piezoelectric element 2 is composed by the metal oscillation plate 4 connected with a free edge of the piezoelectric element 2 by an adhesion agent 11.

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 apparatus, and more particularly, to a structure of an electric connection portion between a piezoelectric element in an ink jet head and the outside.

[0002]

2. Description of the Related Art In a so-called multi-nozzle type ink jet recording apparatus having a large number of ink jet nozzles, a signal line for connecting an individual piezoelectric element corresponding to each nozzle and a drive circuit for driving the individual piezoelectric element. A wire bonding method is generally known as a connection method, but recently, a single laminated piezoelectric element is bonded onto a substrate having an electrode pattern, and the single laminated piezoelectric element is connected to the electrode pattern. According to the above, slit processing is performed so as to divide into a plurality of piezoelectric elements corresponding to each nozzle, and thus, at the same time as the slit processing, the divided individual piezoelectric elements and external electrodes are connected. .

In this case, the individual electrodes of the individual piezoelectric elements are
One electrode of a single laminated piezoelectric element is formed by cutting at the same time as the slit processing, and the common electrode interrupts the slit processing immediately before the other electrode facing the one electrode is cut. And the common electrode is not separated. However, according to this method, it is necessary to interrupt the slit processing before dividing the common electrode of the laminated piezoelectric element, which may damage the piezoelectric element, resulting in poor yield and a cost increase. It was

When ceramics or the like is used as the substrate, a groove is formed on the surface of the ceramic substrate in advance and a common electrode pattern is formed, and a single laminated piezoelectric element is bonded onto the ceramic substrate. , The single laminated piezoelectric element is subjected to the slit processing as described above to divide the single laminated piezoelectric element. In this way, the single laminated piezoelectric element can be divided into a single slit piezoelectric element without interruption. The laminated piezoelectric element can be completely separated into a large number of individual piezoelectric elements.

[0005]

As described above, a method of slitting a substrate and a single laminated piezoelectric element at the same time to divide the single laminated piezoelectric element into a plurality of individual piezoelectric elements is called a piezoelectric method. It is necessary to interrupt the slit processing so that the common electrode side of the element is not separated, the piezoelectric element may be damaged during the processing, and the yield is poor. Further, when ceramics is used as the substrate, it is necessary to perform groove processing on the ceramic substrate in advance, resulting in high manufacturing cost.

The present invention has been made in view of the above circumstances, and improves the workability and the assemblability in the electrical connection between each piezoelectric element of the ink jet head and the external drive circuit, and further reduces the cost. This is done for the purpose of reduction.

[0007]

In order to solve the above-mentioned problems, the present invention has (1) a piezoelectric element corresponding to a nozzle and a metal vibrating plate for transmitting displacement of the piezoelectric element to a liquid chamber, In an inkjet recording apparatus that ejects ink from the nozzles in response to a drive pulse signal to the piezoelectric element, a common electrode for driving the piezoelectric element comprises the metal vibrating plate bonded to a free end of the piezoelectric element, Is (2)
In (1), the free end of the piezoelectric element and the metal diaphragm are joined by a conductive adhesive, and (3) in (1), the free end of the piezoelectric element and the metal. The diaphragm is joined by a non-conductive adhesive containing a conductive gap agent, and further, (4)
In the above (1), the free end of the piezoelectric element and the metal vibration plate are joined by a non-conductive adhesive, and the adhesive layer has a portion where the adhesive is missing. Further, (5) the above ( In any one of 1) to (4), electrodes are provided on both sides of the free end and the fixed end of the piezoelectric element, and the piezoelectric element cooperates with these electrodes to prevent contact with the individual electrodes. The surrounding electrodes are provided so that the common electrode between the laminated piezoelectric elements is an even number and the individual electrode is an odd number. Further, (6) In any one of (1) to (5) above,
The ink is conductive, and the external terminal of the common electrode is electrically connected to the conductive ink.

[0008]

In a multi-nozzle type ink jet head having a laminated piezoelectric element as a driving element, the free end surface of the piezoelectric element is used as a common electrode, and a vibration plate for transmitting the displacement of the piezoelectric element to the liquid chamber is made of a conductive metal. A plate is used, and the common electrode and the vibration plate are electrically connected to each other, and the vibration plate is used as a common electrode for driving the piezoelectric element.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram for explaining the operating principle of an ink jet head to which the present invention is applied.
Is a substrate formed of ceramics or the like, 2 is a laminated piezoelectric element bonded on the surface of the substrate 1, and 3 is a frame arranged so as to surround the piezoelectric element 2, and the upper surfaces of the frame 3 and the piezoelectric element 2 Are positioned so that they are almost in the same plane. Reference numeral 4 denotes a thin film metal vibrating plate joined to the upper surfaces of the piezoelectric element 2 and the frame 3, 5 is a flow path plate made of a resin film, 6 is a nozzle plate made of Si, a metal material, etc., and 6a is Nozzles formed in the nozzle plate 6, 7 are pressurized liquid chamber flow paths, and 8 is a common liquid chamber.

As is well known, the pressurized liquid chamber flow path 7 is composed of a plurality of flow paths arranged in parallel, and the individual piezoelectric elements 2 are provided so as to correspond to the respective pressurized liquid chamber flow paths. Are arranged, and by applying a pulse voltage to the piezoelectric element 2,
The piezoelectric element 2 is displaced, and further, the thin film metal vibrating plate 4 is displaced, whereby the volume of the pressurized liquid chamber flow path 7 is changed and ink is ejected from the nozzle 6a.

FIG. 2 is a diagram for explaining an embodiment of an ink jet head according to the present invention. In the figure, 9 is a common electrode, 10 is an individual electrode, 11 is an adhesive, and others are shown in FIG. The same reference numerals as those in the case of FIG. 1 are attached to the portions having the same operations as those of the inkjet head. In the embodiment shown in FIG. 2, when the laminated piezoelectric elements 2 are arranged at a predetermined pitch to form an actuator unit, the adhesive 1
1, the ground electrode 2a of the piezoelectric element 2 is connected to the common electrode 9, and the common electrode 9 is connected to the thin-film metal diaphragm 4 with the adhesive 11 so as to be electrically connected to the outside. The hot electrode 2b of each piezoelectric element is connected to the individual electrode 10 for each piezoelectric element, but does not come into contact with the free end upper surface (common electrode) of the piezoelectric element 2.

The free end of each piezoelectric element 2 and the thin-film metal vibrating plate 4 are bonded by using an adhesive 11 such as a conductive adhesive or a non-conductive adhesive containing a conductive gap agent. The thin film metal diaphragm 4 and the free end of the piezoelectric element 2 are joined together.
Are directly contacted with each other, and the other parts are joined by the non-conductive adhesive 11. In addition, in FIG.
An example in which the piezoelectric element and its electrode structure used in the embodiment shown in FIG. 2 are formed as a single member will be described.

FIG. 4 is a sectional view of an essential part for explaining another embodiment of the ink jet head according to the present invention. In this embodiment, a free end (upper side in the illustrated example) and a fixed end of the piezoelectric element 2 are shown. The electrodes are arranged so that both surfaces (on the lower side in the illustrated example) become the common electrode 9, and the piezoelectric element 2 is surrounded so that the common electrode 9 does not come into contact with the individual electrode 10.
By doing so, the number of laminated piezoelectric materials is even (6 layers in the illustrated example), the number of common electrodes 2a between the laminated piezoelectric elements is even, and the number of individual electrodes 2b is odd.

Although an example of the piezoelectric element using displacement in the direction perpendicular to the electric field direction (displacement in the d33 direction) has been described in each of the embodiments of the present invention, the present invention is limited to the above embodiment. It can be easily understood that the same effect can be obtained even if a piezoelectric element using a displacement in the same direction as the electric field direction (displacement in the d31 direction) is used. Further, when connecting the common electrode to the outside, the external terminal may be directly connected from the thin film metal diaphragm, but conductive ink may be used and the external terminal may be connected through the conductive ink. Good things can be easily understood.

[0015]

As is apparent from the above description, the present invention has the following effects. (1) Effect corresponding to claim 1: A common electrode for driving a piezoelectric element is formed by a metal vibrating plate that is joined to a free end of the piezoelectric element, so that wire bonding is performed when the common electrode is taken from a plurality of piezoelectric elements. Since it is not necessary to process grooves in ceramics or the like, it is possible to easily perform processing and assembly with less loss, and it is possible to reduce costs. (2) Effect corresponding to claim 2: By using a conductive adhesive, in addition to the effect corresponding to claim 1, it is possible to improve reliability in electrical connection. (3) Effect corresponding to claim 3: By using a non-conductive adhesive mixed with a conductive gap agent, in addition to the effect corresponding to claim 1, improvement in reliability in electrical connection Therefore, the flexibility of the adhesive is increased, so that the optimum adhesive can be used. (4) Effect corresponding to claim 4: Corresponding to claim 1, by providing a portion of the adhesive layer where the piezoelectric element and the metal diaphragm are in direct contact with each other, in the joint portion between the piezoelectric element and the metal diaphragm. In addition to this effect, it becomes possible to improve reliability in electrical connection. (5) Effect corresponding to claim 5: Since the piezoelectric element is surrounded by the common electrode, in addition to the effect corresponding to claim 1,
It is possible to improve electrical reliability. (6) Effect corresponding to claim 6: By using a conductive ink and forming the external common electrode through the ink, in addition to the effect corresponding to claim 1, the degree of freedom in design is increased. It will be possible.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of an inkjet head to which the present invention is applied.

FIG. 2 is a diagram for explaining an embodiment of an inkjet head according to the present invention.

FIG. 3 is a diagram showing a single piezoelectric element used in the inkjet head shown in FIG. 2, in which the piezoelectric element is provided with a common electrode and individual electrodes.

FIG. 4 is a main part configuration diagram for explaining another embodiment of the inkjet head according to the present invention.

[Explanation of symbols]

1 ... Substrate, 2 ... Multilayer piezoelectric element, 2a ... Ground electrode, 2
b ... Hot electrode, 3 ... Frame, 4 ... Vibration plate, 5 ... Flow path plate, 6 ... Nozzle plate, 6a ... Nozzle, 7 ... Pressurized liquid chamber flow path,
8 ... Common liquid chamber, 9 ... Common electrode, 10 ... Individual electrode, 11 ...
adhesive.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Naruse 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Company (72) Inventor Shuzo Matsumoto 1-3-6 Nakamagome, Ota-ku, Tokyo Stocks In Ricoh Company (72) Inventor Tsutomu Sasaki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh (72) Inventor Taeko Murai 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh

Claims (6)

[Claims] 1. An ink jet recording apparatus having a piezoelectric element corresponding to a nozzle and a metal vibrating plate for transmitting a displacement of the piezoelectric element to a liquid chamber, and ejecting ink from the nozzle by a drive pulse signal to the piezoelectric element. 2. The ink jet recording apparatus according to claim 1, wherein the common electrode for driving the piezoelectric element comprises the metal vibrating plate joined to a free end of the piezoelectric element. 2. The ink jet recording apparatus according to claim 1, wherein the free end of the piezoelectric element and the metal vibrating plate are joined by a conductive adhesive. 3. The ink jet recording apparatus according to claim 1, wherein the free end of the piezoelectric element and the metal diaphragm are joined by a non-conductive adhesive containing a conductive gap agent. 4. The free end of the piezoelectric element and the metal vibrating plate are joined by a non-conductive adhesive, and the adhesive layer has a portion where the adhesive is missing. Inkjet recording device. 5. An electrode is provided on both surfaces of a free end and a fixed end of the piezoelectric element, and an electrode surrounding the piezoelectric element is provided so as not to come into contact with an individual electrode in cooperation with these electrodes. 5. The ink jet recording apparatus according to claim 1, wherein the common electrode between the laminated piezoelectric elements is an even number and the individual electrode is an odd number. 6. The inkjet according to claim 1, wherein the ink has conductivity, and an external terminal of a common electrode is electrically connected to the conductive ink. Recording device.