JPH0781058A - Fixing of laminated pzt array - Google Patents

Abstract

PURPOSE:To embody the high printing quality, in a solid ink jet printer using a laminated PZT, by reducing the interference of vibration between respective nozzles and obtaining the stable speed and shape of a liquid droplet. CONSTITUTION:A foot 2 is provided between an ink chamber 9 and a laminated PZT 1 and a back plate 3 for much transmitting the displacement of the laminated PZT 1 to the foot 2 is provided on the opposite side of the laminated PZT 1. The foot 2, the laminated PZT 1 and the back plate 3 are independent at every nozzle and independently bonded to a frame 4 by silicone rubber 7. Therefore, the vibration caused in one nozzle is hardly transmitted to other nozzle.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a monolithic stacked PZT array for a solid ink jet printer.

[0002]

2. Description of the Related Art In the prior art, in order to mount a large number of laminated PZTs on a print head efficiently and accurately, for example, as disclosed in Japanese Patent Laid-Open No. 60-90770, a direction perpendicular to the displacement direction is disclosed. A cut is made in a large laminated PZT having a length substantially the same as the length of all ink chambers with a width corresponding to the ink chamber distance from the front surface in the displacement direction so that the front surface portions of the laminated PZT can be driven independently one by one. The print head is configured by fixing the independent front surface portion of the laminated PZT array to the position corresponding to each ink chamber.

In addition, completely independent P layers for each ink chamber
In the case of using ZT, the laminated PZTs are fixed one by one to a back plate having a length substantially the same as the length of all ink chambers to form a laminated PZT array, and the laminated PZT array is placed at a position corresponding to each ink chamber. Fixed to form the printhead.

Also, in common with these two examples, the laminated P
In the ZT, the front surface in the displacement direction was fixed to the ink chamber and the rear surface was fixed to the back plate. Further, the back plate increases the apparent rigidity and mass, and the laminated PZT
In order to efficiently transmit the vibration energy of the ink to the ink chamber side, it was fixed to the frame body of the print head including the ink chamber.

[0005]

Among the above-mentioned conventional examples, the laminated PZ in which the front face portion contacting each ink chamber is independent
Since the T array is integrated on the back plate side,
The vibrations of the stacked PZT being driven are different from those of the other stacked PZT.
And the interference of vibration occurred, causing the fluctuation of the velocity of the ink droplet ejected from the nozzle.

In the other example, since the vibration of the driven independent stacked PZT is easily transmitted to the other stacked PZT via the back plate, vibration interference occurs and ink droplets ejected from the nozzles. Was causing fluctuations in speed.

Further, in common to these two examples, the laminated PZT is fixed at two points on the ink chamber side and the back plate side, and the rigidity and mass of the back plate are large so that the back plate side is fixed. Of the laminated PZT on the ink chamber side relative to the ink chamber due to the fact that it is stronger than fixing on the ink chamber side, shrinkage due to curing of the adhesive, and temporal deformation of the adhesive and the structural material. The position deviates from the initial assembly position and internal stress is generated, which causes variation in ink ejection characteristics among nozzles.

An object of the present invention is to make a highly productive monolithic laminated PZT array while keeping vibration interference between nozzles low, and accurately hold the position of the laminated PZT with respect to the ink chamber at the initial assembly position. Is.

[0009]

The object is to completely separate a foot, a laminated PZT and a back plate for each ink chamber, and to form a structure in which the laminated PZTs are connected to each other only by a conductive adhesive having low rigidity. , And the back plate is adhered only to the rear surface of the laminated PZT to form the laminated PZT.
This is achieved by adhering only the front surface of the ZT or the foot adhered to the front surface to the frame including the ink chamber wall.

[0010]

In the print head using the laminated PZT array constructed as described above, the laminated PZTs are mainly connected to each other through the thick conductive adhesive. The energy loss of vibration inside the conductive adhesive is caused by the laminated PZT.
Since the energy loss of the vibration inside the PZT or in the back plate is larger than the energy loss of the vibration reaching the other stacked PZT from the stacked PZT being driven, only the front surface independent stacked PZT array constructed by the prior art is used. If
Alternatively, a back plate of continuous shape can be independently laminated P
It is less than when ZT is fixed. As a result, the vibration interference between the ink chambers is reduced as compared with the case of the prior art, and the fluctuation amount of the ink droplet velocity due to the interference is also reduced.

Further, in the laminated PZT according to the present invention, only the tip of the foot is fixed to the frame including the ink chamber wall, and the parts other than the foot are not fixed to the frame, so that the adhesive is hardened and adhered due to aging. The position of the foot with respect to the ink chamber wall does not change even if the volume of the agent changes or the frame or the like deforms.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings.

FIG. 1 is a sectional view taken along the axial direction of a nozzle according to an embodiment of the present invention. In FIG. 1, laminated PZT1
When a driving voltage is applied to the electrodes 10 and 11, is displaced in the displacement direction shown in the figure in proportion to the piezoelectric constant d ₃₃ . The laminated PZ
The back plate 3 is adhered to the rear surface in the displacement direction of T1 with a conductive adhesive. A foot 2 for transmitting vibration energy to the ink chamber 9 is provided on the front surface of the laminated PZT 1.
Are bonded with the conductive adhesive. The foot 2 is made of a material having a large absorption of vibration energy so that the vibration of the laminated PZT 1 can be quickly attenuated after the droplet is ejected, and the foot 2 is made of a material having a large absorption of vibration energy. For example, it is fixed to the diaphragm 5 and the frame 4 via a silicone rubber 7.

The back plate 3 is the laminated PZT1.
Is made of a metal having a large specific gravity in order to transmit a large amount of the displacement to the foot 2 side, and has a mass of about 5 times the total mass of the ink in the ink chamber 9 and the foot 2. Therefore, when the laminated PZT 1 vibrates, the foot 2 is subjected to about 5 times the acceleration of the back plate 3. Therefore, in the nozzle 8 having such a structure, when only the portion of the laminated PZT 1 is fixed and the foot 2, the ink in the ink chamber 9 and the back plate 3 can move freely, the vibration of the ink in the ink chamber 9 The amplitude is 5 times the amplitude of the vibration of the back plate 3. However, in reality, since the nozzle 8 is fixed to the frame 4 by the silicon rubber 7 at the foot 2, the displacement of the foot 2 does not reach up to 5 times the displacement of the back plate 3. However, according to the configuration of this embodiment, the vibration frequency of the laminated PZT1 is 40 kHz.
In the case of the degree, the force generated by the laminated PZT 1 becomes sufficiently larger than the resistance force of the silicone rubber 7, and the foot 2
The silicon rubber 7 is deformed by the force applied to the back plate 3 and the foot 2 is displaced by about 5 times the displacement amount of the back plate 3, and the vibration energy generated by the laminated PZT 1 can be efficiently transmitted to the ink chamber 9. That is, the stack P
If the vibration frequency of ZT1 is constant, the back plate 3 with respect to the total mass of the ink in the foot 2 and the ink chamber 9
The larger the mass ratio is, the more efficiently the vibration energy generated by the laminated PZT 1 is transmitted to the ink chamber 9 side, and therefore the heavier the back plate 3 is. However, the back plate 3 which is too large is not preferable because the print head needs to be upsized. Therefore, in the case of the inkjet nozzle according to this configuration, the most efficient and small print head can be obtained by setting the mass of the back plate 3 to be between 5 times and 50 times the total mass of the ink in the foot 2 and the ink chamber 9. It can be realized.

In this embodiment, since the back plate 3 and the laminated PZT1 are independent of the back plate 3 and the frame 4 bonded to another laminated PZT1, the vibration energy generated in this laminated PZT1 is different from that of the other laminated PZT1.
The amount of interference that occurs when the back plates having a continuous shape between the stacked PZTs 1 is used, and the amount of interference that occurs when the back plate 3 or the stacked PZT 1 is directly bonded to the frame 4 is smaller. Further, since the laminated PZT 1, the foot 2 and the back plate 3 which are integrally bonded are fixed to the frame 4 at only one point of the foot 2, the position of the foot 2 is always constant with respect to the frame 4.

FIG. 2 shows that the laminated PZT1 having the structure shown in FIG. 1 is manufactured integrally for all nozzles. FIG. 2 shows a laminated PZT 1 in which eight sets of nozzles 8 and eight sets of back plates 3 and feet 2 corresponding to the ink chambers 9 are bonded. Since the grooves 15 provided at intervals corresponding to the intervals of the ink chambers 9 are provided between the laminated PZT1 and the adjacent laminated PZT1, all the laminated PZT1s are independent.

In the laminated PZT array, the back plate 3 and the foot 2 are adhered to a large laminated PZT (not shown) having a length substantially the same as the length of the entire ink chamber, and the conductive adhesive 12 is thickly applied to the lower surface. It is produced by cutting the conductive adhesive 12 from the upper surface of the large laminated PZT with a diamond cutter in the displacement direction of the laminated PZT 1 so as not to cut it. As can be seen from the cross section 13 cut by the diamond cutter, the laminated PZT 1, the foot 2 and the back plate 3 are completely independent for each nozzle 8, and the conductive adhesive 12 thickly applied to the lower surface of the laminated PZT 1 is used. They are connected to each other only via the cross-sections 14 which remain uncut.

With such a structure, it is possible to obtain a laminated PZT array which is independent of each other and has good assembly and productivity. Further, as shown in FIG. 1, the laminated PZT array is inserted into an ink chamber frame 6 having eight ink chambers 9 and a frame 4 having eight holes corresponding to the ink chamber frames 6 and bonded with silicone rubber 7. Constitutes a print head.

[0019]

According to the present invention, the front surface of the laminated PZT in the displacement direction is fixed only to the wall surface of the ink chamber directly or indirectly via the foot, so that the position of the laminated PZT with respect to the diaphragm after assembly is fixed. It can be accurately held at the initial assembly position without causing a shift. Further, since the small laminated PZT group having the back plate and the foot is connected to each other only by the conductive adhesive on the lower surface, the large number of laminated PZTs for driving the large number of nozzles can be kept with low vibration interference. It can be manufactured integrally, productivity,
Assembling accuracy can be further improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an example in which the laminated PZT shown in FIG. 1 is manufactured by integrating all nozzles.

[Explanation of symbols]

1 is laminated PZT, 2 is foot, 3 is back plate, 4
Is a frame, 5 is an ink chamber wall, 6 is an ink chamber frame,
7 is silicon rubber, 8 is a nozzle, 9 is an ink chamber, 10 is an electrode, 11 is an electrode, 12 is a conductive adhesive, and 15 is a groove.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazunobu Hayashi 1060 Takeda, Katsuta City, Ibaraki Prefecture Hitachi Koki Engineering Co., Ltd.

Claims (3)

[Claims] 1. In a solid inkjet printer using a laminated PZT, one end of the laminated PZT corresponding to each ink chamber in the displacement direction is fixed directly or indirectly via a foot to the wall surface of the ink chamber, and the other end is fixed. A method of fixing a laminated PZT, which comprises fixing to a back plate provided so as to correspond to each ink chamber. 2. The method for fixing a laminated PZT according to claim 1, wherein the mass of the back plate is between 5 and 50 times the mass of the ink in the ink chamber plus the mass of the foot. A method for fixing a laminated PZT which is a feature. 3. The back plate is bonded to the rear surface of the large laminated PZT having a length substantially the same as the length of the entire ink chamber in the direction perpendicular to the displacement direction, the foot is bonded to the front surface, and the bottom surface is bonded to the lower surface. Is coated with a conductive adhesive which serves as a common electrode of the laminated PZT, and cuts the laminated PZT, the back plate and the foot with a width corresponding to an ink chamber interval from the upper surface and completely cuts the back plate and the back plate. A method for fixing an integrated laminated PZT array, characterized in that small laminated PZT groups having feet are connected to each other only with a conductive adhesive on the lower surface.