JP2871473B2 - Head for inkjet printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer head, and more particularly, to a piezoelectric element which is deformed by electric energy to displace a diaphragm, thereby increasing the pressure in a pressure chamber and discharging ink droplets from nozzle holes. The present invention relates to an ink jet printer head.

[0002]

2. Description of the Related Art Conventionally, an ink jet printer head for increasing the pressure in a pressure chamber by deforming a piezoelectric element by electric energy to displace a vibration plate and ejecting ink droplets from nozzle holes is shown in FIG. As shown in the figure, a pressure chamber 32a having nozzle holes 31a to 31c
To 32c are formed, respectively, a pressure chamber forming member 33,
It comprises a vibration plate 34 and a comb-shaped piezoelectric element 36 on which piezoelectric element teeth 35a to 35e are formed.

A pressure chamber forming member 33 is adhered on the vibration plate 34 so that the nozzle holes 31a to 31c are respectively directed upward, and piezoelectric element teeth 35a, 35b,
The end faces of the piezoelectric element teeth are adhered to the outer surfaces of the pressure chambers so that 35c respectively correspond to the pressure chambers 32a, 32b, and 32c, and both end teeth 35d, 35e of the comb-shaped piezoelectric element 36.
Is also adhered to the lower portion of the diaphragm 34.

In a conventional ink-jet printer head having such a configuration, by applying a voltage in the polarization direction of the piezoelectric element 36, a desired one of the piezoelectric element teeth 35a to 35b is displaced upward in the drawing. As a result, the diaphragm 34 is also displaced upward, and the pressure chambers 32 a to 32
The pressure in the pressure chamber at the position corresponding to the displaced piezoelectric element tooth of c is increased, and the ink droplet is ejected from the nozzle hole of the pressure chamber.

Conventionally, a piezoelectric element is bonded to a lower surface of a substrate to which a comb-shaped piezoelectric element is adhered, and is driven simultaneously with the comb-shaped piezoelectric element on the upper surface to reduce the deformation of the piezoelectric element. An ink jet printer head is also known (Japanese Patent Laid-Open No. 3-247454: title of the invention "ink jet head").

[0006]

The conventional ink jet printer head shown in FIG.
The six end teeth 35d and 35e are bonded to the diaphragm 34 for positioning or fixing the comb-shaped piezoelectric element 36. In the conventional head having such a configuration, the longitudinal effect or the lateral effect of the comb-shaped piezoelectric element 36 is used, and the displacement direction due to the application of the voltage is always a single direction. When it is necessary to increase the generated pressure, the diaphragm 34 needs to be largely displaced in a single direction by increasing the voltage applied to the piezoelectric element teeth 35a.

[0007] Then, the absolute amount of displacement of the diaphragm 34 increases, and the diaphragm 34 at a portion corresponding to the adjacent pressure chambers 32b and 32c is also displaced, adversely affecting its behavior. Piezoelectric element teeth 35a and diaphragm 3
Since the load applied to the bonding surface with the pressure plate 4 and the bonding surface between the pressure chamber boundary walls 37b and 37c and the vibration plate 34 also increases, the bonding surface is peeled off, which adversely affects the ink droplet ejection behavior thereafter. There's a problem.

The vibration plate 34 and the piezoelectric element teeth 35a, 3
If the bonding position with the nozzles 5b and 35c is not accurate, this causes a problem that ink droplets from the plurality of nozzle holes 31a, 31b and 31c fly or ink droplets are not ejected.

Further, in the latter conventional ink jet printer head having a structure in which the piezoelectric element is bonded to the lower surface of the base to which the comb-shaped piezoelectric element is bonded, the piezoelectric element on the lower surface must be separately formed. , Wiring man-hours increase,
There is a problem that the cost increases.

[0010] The present invention has been made in view of the above points,
Ink droplet ejection operation can be performed with a single piezoelectric element, the displacement of the diaphragm can be increased without changing the load on the diaphragm from the conventional one, and the positioning of the diaphragm and the piezoelectric element is easy,
It is another object of the present invention to provide an ink jet printer head that can be made accurate.

[0011]

Since the present invention SUMMARY OF THE INVENTION The To achieve the above object, a plurality of pressure chambers with their respective nozzle holes, vibration plate top pressure chamber forming member formed as one wall surface of the Is fixed to the upper surface of the vibration plate, the upper end surface of the piezoelectric element is fixed to the lower surface of the vibration plate, and the vibration plate is deformed by the piezoelectric element to increase the pressure in the pressure chamber to eject ink droplets from the nozzle holes. In an ink jet printer head for printing, the piezoelectric elements are parallel in the longitudinal direction and the base is shared.
A plurality of comb-shaped piezoelectric element teeth, and a group of piezoelectric element teeth formed such that an upper end face is located at a position corresponding to each of the plurality of pressure chambers among the plurality of comb-shaped piezoelectric element teeth. To displace the entire plurality of comb-shaped piezoelectric element teeth.
And the piezoelectric element teeth for whole displacement of the piezoelectric element formed in order to fix the upper end face of the piezoelectric element teeth group to the lower surface of the diaphragm at the position corresponding to each of the plurality of pressure chambers, and the internal electrodes for driving the dentate piezoelectric element teeth each, independently of one another is provided, and independently driven and controlled to the piezoelectric element teeth piezoelectric element dental whole piezoelectric element displacement, the piezoelectric element teeth
The entire group is changed in the same direction as the piezoelectric element teeth for overall piezoelectric element displacement.
And a plurality of pressure chamber volumes are simultaneously changed .

[0012]

[0013]

According to the present invention, the piezoelectric element includes a piezoelectric element tooth group formed so that an upper end face is located at a position corresponding to each of the plurality of pressure chambers, and a remaining piezoelectric element formed for displacement of the entire piezoelectric element. The piezoelectric element teeth group displaces the piezoelectric element teeth provided at positions corresponding to the pressure chambers from which ink droplets are to be ejected. The entire piezoelectric element is displaced by driving displacement independently of the teeth.

Therefore, in the present invention, the piezoelectric element teeth for whole piezoelectric element displacement and the piezoelectric element teeth group are sequentially and independently driven to be provided at positions corresponding to the pressure chambers from which ink droplets are to be ejected. The diaphragm portion fixed to the set piezoelectric element teeth can be displaced more than before.

[0015]

Next, an embodiment of the present invention will be described. FIG. 1 is a structural sectional view of one embodiment of the present invention, and FIG. 2 is an exploded perspective view of one embodiment of the present invention. In both figures, the same components are denoted by the same reference numerals. As shown in both figures, in the present embodiment, a comb-teeth-shaped piezoelectric element 1 made of, for example, ceramics,
, The pressure chamber forming member 3, the fixing block 4, and the diaphragm fixing member 5.

The comb-shaped piezoelectric element 1 has relatively wide piezoelectric element teeth 1a and 1i formed at both ends with the same length.
Between the piezoelectric element teeth 1a and 1i in a direction orthogonal to the longitudinal direction, piezoelectric element teeth 1b, 1c, 1d, 1e, 1
f, 1g and 1h are formed with the same width and the same length. The piezoelectric element teeth 1a and 1i correspond to the piezoelectric element teeth 1b to 1b.
The length is longer than h.

The pressure chamber forming member 3 is adhered on the vibration plate 2 so as to form pressure chambers 7 b to 7 h having nozzle holes 6 b to 6 h, respectively. As shown in FIG. 2, the diaphragm 2 and the pressure chamber forming member 3 penetrate the piezoelectric element teeth 1 a and 1 i at both ends of the comb-shaped piezoelectric element 1 at positions opposed to the piezoelectric element teeth 1 a and 1 i. Through holes 9a and 9b are formed.

As a result, both ends of the piezoelectric element teeth 1 a and 1 i of the comb-shaped piezoelectric element 1 are formed by the diaphragm 2 and the pressure chamber forming member 3.
Are fixed to the inner surface of the fixed block 4 through the through holes 9a and 9b. As a result, the positioning of the piezoelectric element teeth 1b to 1h corresponding to the pressure chambers 7b to 7h is facilitated. The upper end surfaces of the piezoelectric element teeth 1 b to 1 h positioned at the positions are bonded to the lower surface of the diaphragm 2.

As shown in FIG. 2, the comb-shaped piezoelectric element 1, the vibration plate 2, the pressure chamber forming member 3, and the fixing block 4, which are positioned and adhered to each other, are fixed by a hollow quadrangular prism-shaped vibration plate fixing member 5. Is done. At this time, the inner side surface of the fixed block 4 is in close contact with the outer side surface of the diaphragm fixing member 5, and the lower surface outside the position where the through holes 9 a and 9 b of the diaphragm 2 are formed is bonded to the upper end surface of the fixing member 5. Fixed.

Note that all the piezoelectric element teeth 1a to 1i of the comb-shaped piezoelectric element 1 are provided with independent wirings, respectively, and are configured to be independently driven and controlled.

Next, the operation of this embodiment will be described.
First, a case where the comb-teeth-shaped piezoelectric element 1 shown in FIG. 1 is a piezoelectric element using the so-called longitudinal effect in which the internal electrodes 11a and 11b are formed on a surface parallel to the bottom surface as shown in FIG. . The internal electrode 11a is an electrode common to all the piezoelectric element teeth 1a to 1i, and the internal electrode 11b is an electrode provided individually for each of the piezoelectric element teeth 1a to 1i.

First, a voltage is applied to both ends of the piezoelectric element teeth 1a and 1i. Then, both ends of the piezoelectric element teeth 1a and 1i tend to extend in the longitudinal direction of FIGS. 1, 2 and 3, respectively. However, since the upper end surfaces of the both end piezoelectric element teeth 1a and 1i are fixed to the fixed block 4, The piezoelectric element teeth 1a and 1i at both ends are directed downward in FIGS.
−X direction).

As a result, the piezoelectric element teeth 1b to 1h also have -X
, And the bonded portion between the piezoelectric element teeth 1b to 1h and the vibration plate 2 is displaced in the -X direction. As a result, the pressure in all the pressure chambers 7b to 7h can be reduced.

Subsequently, the voltage applied to the piezoelectric element teeth 1a and 1i at both ends is removed, and at the same time, all the pressure chambers 7b to 7h are removed.
A voltage is applied to the piezoelectric element teeth corresponding to the pressure chamber having the nozzle hole from which the ink droplet is to be ejected. For example,
When ink droplets are to be ejected from the nozzle holes 6b and 6d, the piezoelectric element teeth 1 corresponding to the pressure chambers 7b and 7d
A voltage is applied only to each of the wirings b and 1d.

Since the displacement of the piezoelectric element teeth 1a and 1i in the -X direction is returned to the original state by removing the voltage applied to the piezoelectric element teeth 1a and 1i at the both ends, the diaphragm 2 returns to the original shape.
Also, by applying a voltage to the wiring of the piezoelectric element teeth 1b and 1d corresponding to the pressure chambers 7b and 7d having the nozzle holes for ejecting the ink droplets, for example, 6b and 6d, the piezoelectric element teeth 1b and 1d Although each of the piezoelectric elements 1b and 1d is to extend in the ± X direction, the lower end of each of the piezoelectric element teeth 1b and 1d is connected to the base of the piezoelectric element 1, so that the diaphragm adhered to the upper end surfaces of the piezoelectric element teeth 1b and 1d. 2
Is displaced in the + X direction.

Thus, according to this embodiment, the portion of the vibration plate 2 adhered to the upper end surfaces of the piezoelectric element teeth 1b and 1d corresponding to the pressure chamber having the nozzle hole from which the ink droplet is to be ejected, Since the displacement returns from the initial −X direction to the original shape and is further displaced in the + X direction, the amount of displacement of the portion of the diaphragm 2 can be reduced without changing the load applied to the diaphragm 2 to the conventional one. It can be larger than before.

Therefore, according to this embodiment, the piezoelectric element teeth 1
The adhesive surface between b to 1h and the diaphragm 2 and the adhesive surface between the pressure chamber boundary wall and the diaphragm 2 are not peeled off, and the positioning of the diaphragm 2 and the piezoelectric element teeth 1b to 1h is easy and accurate. As a result, ink droplets can be accurately ejected by a single piezoelectric element 1.

Next, as shown in FIG. 4, the comb-shaped piezoelectric element 1 shown in FIG.
The case where the piezoelectric element 1b is formed, that is, a piezoelectric element utilizing a so-called lateral effect will be described. The internal electrode 21a is an electrode common to all the piezoelectric element teeth 1a to 1i, and the internal electrode 21b is an electrode provided individually for each of the piezoelectric element teeth 1a to 1i.

First, the piezoelectric element teeth 1b, 1c, 1d, 1e, 1f, 1g and 1 excluding the piezoelectric element teeth 1a and 1i at both ends.
A voltage is applied to h.

Thus, the piezoelectric element teeth 1b, 1c, 1
d, 1e, 1f, 1g, and 1h extend in the direction perpendicular to the lamination direction of the electrodes 21a and 21b, that is, in the horizontal direction, and contract in the vertical direction (± X direction). , 1c, 1d, 1e, 1f, 1g, and 1h are connected to the base of the piezoelectric element 1, respectively, so that the upper end surfaces adhered to the diaphragm 2 are displaced in the -X direction by contraction. You. This allows
The pressure in all the pressure chambers 7b to 7h corresponding to the piezoelectric element teeth 1b to 1h can be reduced.

Subsequently, the voltage application to the piezoelectric element teeth corresponding to the pressure chamber having the nozzle hole from which the ink droplet is to be ejected among all the pressure chambers 7b to 7h is released,
A voltage is applied to both ends of the piezoelectric element teeth 1a and 1i. For example, when an ink droplet is to be ejected from the nozzle holes 6b and 6d, the voltages applied to the respective wires of the piezoelectric element teeth 1b and 1d corresponding to the pressure chambers 7b and 7d are released.

Since the displacement of the piezoelectric element teeth 1b and 1d in the -X direction returns to the original state by removing the voltage applied to the piezoelectric element teeth 1b and 1d, the shape of the portion of the diaphragm 2 adhered to them is changed. Simultaneously with the return to the original shape, and by applying a voltage to both ends of the piezoelectric element teeth 1a and 1i, the both ends of the piezoelectric element teeth 1a and 1i contract in the vertical directions (± X directions) of FIGS. 1, 2 and 4, respectively. try to.

However, since the upper end surfaces of the both ends piezoelectric element teeth 1 a and 1 i are fixed to the fixed block 4, the both end piezoelectric element teeth 1 a and 1 i are displaced in the + X direction. Accordingly, the piezoelectric element teeth 1b to 1h are also displaced in the + X direction, and the bonding portion between the piezoelectric element teeth 1b to 1h and the diaphragm 2 is displaced in the + X direction.

Therefore, according to this embodiment, even when the piezoelectric element utilizing the lateral effect shown in FIG. 4 is used, the piezoelectric element teeth 1b and 1d corresponding to the pressure chamber having the nozzle hole for ejecting the ink droplet are used. The portion of the diaphragm 2 adhered to the upper end surface returns to the original shape from the initial displacement in the −X direction, and
Since the displacement occurs in the X direction, the displacement amount of the portion of the diaphragm 2 can be made larger than that of the related art without changing the load applied to the diaphragm 2 to the conventional one.

Therefore, also in this case, the piezoelectric element teeth 1b-1
h and the bonding surface between the pressure chamber boundary wall and the vibration plate 2 are not peeled off, and the vibration plate 2 and the piezoelectric element teeth 1 are not separated.
Positioning between b and 1h can be easily and accurately performed, and ink droplets can be accurately discharged by a single piezoelectric element 1.

In the above embodiment, the voltage applied to the piezoelectric element teeth 1a and 1i is
When only a and 1i are driven, it is necessary to set the voltage within a range where ink is not ejected.

The present invention is not limited to the above-described embodiment. For example, when the length of the piezoelectric element teeth 1a and 1i at both ends is the same as the length of the piezoelectric element teeth 1b to 1h located at other intermediate positions, the vibration It may be configured to be fixed to the plate 2 by adhesion. However, in this case, the upper part of the vibration plate 2 bonded to the piezoelectric element teeth 1a and 1i needs to be fixed by a fixing block.

In the above embodiment, the piezoelectric element teeth for displacing the entire comb-teeth-shaped piezoelectric element 1 are the two-end piezoelectric element teeth 1a and 1i located at both ends of the piezoelectric element 1. The position is not limited to these two end positions as long as it is formed from the above piezoelectric elements.

[0039]

As described above, according to the present invention,
Vibration fixed to the piezoelectric element teeth provided at positions corresponding to the pressure chambers where ink droplets are to be ejected by sequentially and independently driving the piezoelectric element teeth for whole piezoelectric element displacement and the piezoelectric element teeth group Because the plate portion is displaced more than before, the pressure generated in the pressure chamber for ejecting ink droplets can be increased while the load on the diaphragm remains the same as before, and the piezoelectric element teeth and Peeling of the adhesive surface with the diaphragm and adverse effects on other diaphragm portions can be prevented.

In the present invention, the piezoelectric element teeth for displacing the entire piezoelectric element are provided at both ends of the piezoelectric element with a length longer than the piezoelectric element teeth group, and the piezoelectric element teeth at both ends are connected to the pressure chamber forming member and the vibration member. Since the upper end face is fixed to the fixed block by penetrating through holes formed in each of the plates, positioning of the piezoelectric element teeth group can be performed easily and accurately.

[Brief description of the drawings]

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

FIG. 2 is an exploded perspective view of one embodiment of the present invention.

FIG. 3 is a perspective view when a piezoelectric element utilizing a longitudinal effect is used for the piezoelectric element of the embodiment of FIG. 1;

FIG. 4 is a perspective view when a piezoelectric element utilizing a lateral effect is used for the piezoelectric element of the embodiment of FIG. 1;

FIG. 5 is a cross-sectional view of an example of a conventional configuration.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Piezoelectric element 1a, 1i Both ends piezoelectric element teeth for overall displacement of piezoelectric element 1b, 1c, 1d, 1e, 1f, 1g, 1h Piezoelectric element teeth 2 Vibrating plate 3 Pressure chamber forming member 4 Fixed block 5 Vibrating plate fixing member 6b, 6c , 6d, 6e, 6f, 6g, 6h Nozzle hole 7b, 7c, 7d, 7e, 7f, 7g, 7h Pressure chamber 9a, 9b Through-hole 11a, 11b, 21a, 21b Internal electrode

Claims (1)

(57) [Claims] A pressure chamber forming member having a plurality of pressure chambers each having a nozzle hole is formed on the upper surface of the diaphragm as one wall surface, and a pressure chamber forming member is fixed to the upper surface of the diaphragm, and a piezoelectric member is provided on the lower surface of the diaphragm. An ink jet printer head for fixing the upper end surface of the element, deforming the vibration plate by the piezoelectric element to increase the pressure in the pressure chamber, and ejecting ink droplets from the nozzle holes for printing, wherein the piezoelectric element is A plurality of comb-shaped piezoelectric element teeth whose longitudinal directions are parallel and have a common base, and an upper end face is located at a position corresponding to each of the plurality of pressure chambers among the plurality of comb-shaped piezoelectric element teeth. And a plurality of piezoelectric element teeth for whole piezoelectric element displacement formed for displacing the plurality of comb-teeth-shaped piezoelectric element teeth. Each An upper surface of the teeth of the piezoelectric element group is fixed to a lower surface of the diaphragm at a corresponding position, and an internal electrode is provided for driving the plurality of comb-shaped piezoelectric element teeth independently of each other; The whole displacement piezoelectric element teeth are driven and controlled independently of the piezoelectric element teeth group, and the whole piezoelectric element teeth group is displaced in the same direction as the piezoelectric element whole displacement piezoelectric element teeth. An ink jet printer head characterized by simultaneously changing the volume.