JP2002234155A - Piezoelectric ink jet printer head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the ink jet performance from deteriorating due to extremely rigidity of the cavity plate unit in an ink jet printer head. SOLUTION: A cavity plate unit 10 comprises a stack of a base plate 14 provided with pressure chambers 16, a manifold plate 12 provided with manifold chambers 12a for implementing each pressure chamber 16 with ink, a spacer plate 13 and a lower layer plate 11 placed, respectively, on the upper and lower surfaces of the manifold plate 12, and a nozzle plate 43 provided with nozzles 54 communicating with the pressure chambers wherein the pressure chambers 16 are driven selectively at the active section of a piezoelectric actuator. The manifold chambers 12a are formed in the manifold plate 12 while straddling a plurality of pressure chambers 16 in the arranging direction and thin recesses 55 opening to the manifold chamber 12a side are formed in the spacer plate 13 while straddling a plurality of pressure chambers 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric ink jet printer head.

[0002]

2. Description of the Related Art A prior art on-demand type piezoelectric ink jet printer head is disclosed in Japanese Unexamined Patent Publication No. Hei.
As described in Japanese Patent No. 41856, a plurality of nozzles and a pressure chamber (ink cavity) for each nozzle
And a piezoelectric element for selectively driving the rear surface of a manifold plate provided with an ink manifold that is in communication with the pressure chamber and that supplies ink through a diaphragm serving as a diaphragm in accordance with the pressure chamber location. An ink jet printer head having a cover plate provided with an energy generating unit such as the above is fixedly disclosed.

When the piezoelectric element is driven and vibrated, the pressure chamber is selectively pressurized via a vibration plate, and the pressure is transmitted to a corresponding nozzle hole, and printing is performed by discharging ink droplets. Be executed. At this time, the pressure wave acting on the pressure chamber has not only a forward component toward the nozzle hole but also a backward component toward the ink manifold. Because of the backward component, so-called crosstalk occurs,
The retreat component is intended to be absorbed and relaxed in a damper chamber formed in the cover plate.

Incidentally, the present applicant has filed a Japanese Patent Application No. 2000-6.
In No. 2106 and the like, two manifold plates provided with a manifold are laminated adjacent to a base plate provided with a pressure chamber, a nozzle plate is arranged on a lower surface of a lower manifold plate, and each plate is coated with an adhesive. A cavity plate unit is formed by lamination and fixing, and a plate-shaped piezoelectric actuator incorporating a piezoelectric element is bonded to the upper surface of the base plate in this cavity plate unit so as to face the position corresponding to each pressure chamber. A fixed one was proposed.

[0005] With this configuration, the pressure chamber and the manifold can be arranged at overlapping positions within the area of the cavity plate unit in plan view, so that the ink jet head can be made compact.

[0006]

However, in the above configuration, since the cavity plate unit has a plurality of plates made of a metal plate or the like having high rigidity, the plate is laminated when the piezoelectric element is selectively driven. As the active part of displacement by the piezoelectric element elastically deforms so as to curve the plane of the plate of the piezoelectric actuator, the cavity plate unit bonded to the piezoelectric actuator also elastically deforms. If the rigidity of the pressure chambers is high, the elastic deformation affects unnecessary (unselected) pressure chambers, and a so-called cross talk phenomenon occurs, which affects the ejection of ink from the pressure chambers. As a result, there has been a problem that ink droplets to be ejected are in the form of droplets.

An object of the present invention is to provide an ink jet printer head which solves such a problem.

[0008]

In order to achieve this technical object, the invention according to claim 1 comprises a plurality of nozzles and pressure chambers for each of the nozzles in a row in a first direction. In a piezoelectric ink-jet printer head comprising a cavity plate unit and a piezoelectric actuator having an active portion which can be selectively driven for each of the pressure chambers and ejecting ink, the cavity plate unit is provided with the pressure chamber. A manifold plate provided with a manifold chamber for storing ink from an ink supply source and then refilling the pressure chambers; a spacer plate interposed between the manifold plate and the base plate; And a nozzle plate provided with a nozzle communicating with the pressure chamber, and the manifold The manifold plate is formed on the manifold plate so as to straddle in the direction in which the plurality of pressure chambers are arranged.On the other hand, the spacer plate has at least the plurality of thin-walled recesses opened to the manifold chamber side. It is formed so as to straddle the pressure chamber.

The invention described in claim 2 is the first invention.
Wherein the thin-walled recess is formed to have substantially the same size as the manifold chamber.

According to a third aspect of the present invention, in the ink jet printer head according to the first aspect, the longitudinal direction of the manifold chamber is arranged so as to intersect with the arrangement direction of the plurality of pressure chambers, and the thin wall is formed. The concave portion is formed in a long groove shape extending over substantially the entire length of the manifold chamber and straddling the plurality of pressure chambers.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 7 show a piezoelectric ink jet printer head of the present invention. In these figures, a flexible flat cable 40 is bonded on an upper surface of a plate-type piezoelectric actuator 20 bonded to the cavity plate unit 10 with an adhesive for connection with an external device. It is assumed that ink is ejected downward from the nozzle 54 opened on the lower surface side of the cavity plate unit 10.

The cavity plate unit 10 according to the first embodiment is configured as shown in FIGS. That is, the nozzle plate 43, the lower plate 11, the manifold plate 12, the spacer plate 1
This is a structure in which five thin plates of the base plate 3 and the base plate 14 are laminated by bonding and joined. In the embodiment, each plate 11, 12, 13, 14 except the nozzle plate 43 is provided.
Is made of 42% nickel alloy steel plate, and 50 μm to 150 μm
About the thickness. In the nozzle plate 43, nozzles 54 for ejecting ink having a small diameter are provided in a staggered arrangement in two rows along a first direction (long side direction) of the nozzle plate 43. That is, the nozzle plate 43
Two reference lines 43a and 43b parallel to the first direction
, A large number of nozzles 54 are formed in a staggered arrangement at intervals of a minute pitch P.

The pressure chambers 16 described below corresponding to the nozzles 54 and the active portions of the piezoelectric elements in the piezoelectric actuator 20 described later are arranged so as to be vertically overlapped and correspond to each other in plan view of each plate. Each of the pressure chambers 16 is formed so as to extend in a direction intersecting (perpendicular to) the first direction, and a row of the pressure chambers 16 extends along the first direction. In the manifold plate 12, a pair of manifold chambers 12a serving as ink passages are formed so as to extend along both sides of the row of the nozzles 54. In this case, each of the manifold chambers 12a extends so as to overlap the row of the pressure chambers 16 and straddle the row of the pressure chambers 16 in a plan view of the plate (see FIGS. 3 and 4).

Each of the manifold chambers 12a of the manifold plate 12 is sandwiched between a lower layer plate 11 and an upper spacer plate 13 and is sealed by being laminated.

The base plate 14 has a plurality of narrow pressure chambers 16 extending in a second direction (short side direction) orthogonal to a center line along the long side (the first direction). Are drilled. When the longitudinal reference lines 14a and 14b are set in parallel on both the left and right sides of the center line, the tip 16a of the pressure chamber 16 on the left side of the center line is located on the left longitudinal reference line 14a, Conversely, the tip 16a of the pressure chamber 16 on the right side of the longitudinal center line is located on the right longitudinal reference line 14b.
Since the six tips 16a are alternately arranged, the pressure chambers 16 on the left and right sides are alternately arranged so as to extend every other direction in opposite directions (see FIG. 4).

The tips 16a of the pressure chambers 16 are connected to the staggered nozzles 54 in the nozzle plate 43.
Are connected to the spacer plate 13, the manifold plate 12, and the lower plate 11 through small-diameter through holes 17, which are also formed in a staggered arrangement. On the other hand, the other end 16b of each of the pressure chambers 16 communicates with a manifold chamber 12a of the manifold plate 12 through through holes 18 formed in both left and right portions of the spacer plate 13. The other end 16b is connected to the base plate 1 as shown in FIG.
4 is recessed so as to be opened only on the lower surface side. A filter 29 for removing dust in ink supplied from an ink tank above the supply hole 19a is provided on an upper surface of a supply hole 19a formed in one end of the uppermost base plate 14.

Thus, supply holes 19a, 19 formed in one end of the base plate 14 and the spacer plate 13 from an ink supply source (ink tank) not shown.
b, the ink flowing into the left and right manifold chambers 12a, 12a is distributed from the ink passages 12a into the pressure chambers 16 through the through holes 18, and then into the pressure chambers 16a. It is configured to pass from the inside through the through hole 17 to the nozzle 54 corresponding to the pressure chamber 16 (see FIGS. 3 and 6).

On the lower surface of the spacer plate 13, a thin recess opened toward the manifold chamber 12a is formed so as to straddle at least the plurality of pressure chambers 16. In the first embodiment, as shown in FIGS. 4 and 7, the longitudinal direction (extending direction) of each of the manifold chambers 12a intersects (perpendicularly) with the arrangement direction (first direction) of the plurality of pressure chambers 16. The thin-walled concave portion (concave groove) 55 is disposed so as to extend in the second direction, and is formed in a long groove shape that extends over substantially the entire length of the manifold chamber 12 a and straddles the plurality of pressure chambers 16. Is what is being done. In the embodiment, two rows of recesses 55 are formed for each manifold chamber 12a.

In another embodiment, as shown in FIG. 8, the thin-walled recess 56 is formed to have substantially the same size as the manifold chamber 12a and the same shape in plan view.

These thin recesses 55 (56) have a slightly lower rigidity so that the elastic deformation of the portion of the spacer plate 13 corresponding to the active portion of the piezoelectric element is appropriately performed as described later. Is what you do.

On the other hand, as shown in FIGS. 2 and 5, the piezoelectric actuator 20 has nine piezoelectric sheets 21a and 21a.
1b, 21c, 21d, 21e, 21f, 21g, 2
2 and 23 are stacked, and the uppermost surface (wide surface) of the lowermost piezoelectric sheet 22 and the odd-numbered piezoelectric sheets 21b, 21d, and 21f counted upward from the piezoelectric sheet 22 is formed.
In each of the pressure chambers 16 in the cavity plate unit 10, narrow individual electrodes 24 are formed in a row along a first direction (long side direction). Each piezoelectric sheet extends in the second direction orthogonal to the first direction to the vicinity of the long edge of each piezoelectric sheet. Even-numbered piezoelectric sheets 21a, 21c, 21e, 21g from the bottom
A common electrode 25 common to the plurality of pressure chambers 16 is formed on the upper surface (wide surface).

In the embodiment, each of the individual electrodes 24
Is set slightly smaller than the corresponding wide portion of the pressure chamber 16 in plan view.

On the other hand, the pressure chambers 16 are arranged in two rows along the first direction (long side) at the center of the short side of the base plate 14, so that the common electrodes 25 are formed.
The piezoelectric sheets 21 a, 21 c, 21 e, and 2 of even-numbered stages are formed so as to integrally cover the two rows of pressure chambers 16.
In the center of the short side direction of 1 g, it is formed in a substantially rectangular shape extending along the long side in a plan view. Drawers 25a, 25a extending over substantially the entire length of the edge are integrally formed.

The even-numbered piezoelectric sheets 21
The same vertical position (corresponding position) as each of the individual electrodes 24 is provided on the surface near the long edge of the pair of a, 21c, 21e, and 21g where the common electrode 25 is not formed. Then, a dummy individual electrode 26 having the same width and a short length as the individual electrode 24 is formed. In this case, as shown in FIG. 5, the end of each dummy individual electrode 26 has a gap with an appropriate gap dimension with respect to the side edge of the common electrode 25 in the first direction (along the long side). Separated. The length of every other layer of the dummy individual electrode 26 is L2 and L3 (<L
The length is set to be short or long as shown in 2), and the position of the break in the pattern between the end of the dummy individual electrode 26 and the side edge of the common electrode 25 is set every other layer of the piezoelectric sheet.
(Short side direction). In the embodiment,
The length L of the dummy individual electrode 26 in the second layer (piezoelectric sheet 21a) and the sixth layer (piezoelectric sheet 21e) from the bottom
2 is the length L of the dummy individual electrode 26 in the fourth layer (piezoelectric sheet 21c) and the eighth layer (piezoelectric sheet 21g).
It is set to be longer than 3 by the gap size.

On the other hand, the lowermost piezoelectric sheet 22 and the odd-numbered piezoelectric sheets 21b, 21d, 2
1f, the lead-out portions 25a,
The dummy common electrode 27 is formed at a position corresponding to 25a (the same vertical position, near the short edge of the pair of piezoelectric sheets).

On the upper surface of the uppermost top sheet 23, a surface electrode 30 for each of the individual electrodes 24 and a surface electrode 31 for the common electrode 25 are formed along an edge of a long side thereof. (See FIG. 2).

Further, except for the lowermost piezoelectric sheet 22, all the other piezoelectric sheets 21a, 21b, 21c,
21d, 21e, 21f, 21g and the top sheet 23, the surface electrodes 30 and the individual electrodes 24 and the dummy individual electrodes 26 at the corresponding positions (the same vertical position) are provided.
Are formed so as to communicate with each other. Similarly, the at least one surface electrode 31 (in the embodiment, the surface electrodes 3 at the four corners of the top sheet 23)
1) and a through-hole 33 is formed so that the common electrode 25 at the corresponding position (the same vertical position) or the lead portion 25a thereof communicates with each other.
The individual electrodes 24 of each layer and the surface electrode 30 at a position corresponding to the individual electrodes 24 are interposed via the conductive material filled in the inside 2 and 33.
Are electrically connected, and similarly, the common electrodes 25 of each layer are electrically connected to the surface electrode 31 at a position corresponding to the common electrodes 25.

In this way, the plurality of piezoelectric sheets 21 and the top sheet laminated one above the other are electrically connected with the individual electrodes 24 and the dummy individual electrodes 26 at the same position in the vertical direction with the location of the surface electrode 30. Similarly, a plurality of upper and lower common electrodes 25 and dummy common electrodes 27 are electrically connected to the location of the surface electrode 31 (see FIG. 6).

Then, an adhesive sheet 41 made of an ink-impermeable synthetic resin material as an adhesive layer is formed on the entire lower surface (wide surface facing the pressure chamber 16) of the plate-type piezoelectric actuator 20 having such a configuration. Beforehand,
Next, the individual electrodes 2 of the piezoelectric actuator 20 are applied to the cavity plate unit 10.
4 are bonded and fixed so as to correspond to each of the pressure chambers 16 in the cavity plate unit 10 (see FIGS. 7 and 8). The flexible flat cable 40 is overlaid and pressed on the upper surface of the piezoelectric actuator 20, so that various wiring patterns (not shown) of the flexible flat cable 40 are applied to the surface electrodes 30, 31. Electrically connected to

The material of the adhesive layer such as the adhesive sheet 41 is a material which is at least impermeable to ink and has electrical insulation, and is made of polyamide resin based on nylon or dimer acid. A film-shaped hot melt adhesive of a polyamide type or a polyester hot melt type adhesive as a main component may be used, but a polyolefin hot melt type adhesive is applied to the wide surface of the piezoelectric actuator 20. After that, it may be bonded and fixed to the cavity plate unit 10. The thickness of the adhesive layer is about 1 μm.

In this configuration, of the individual electrodes 24 in the piezoelectric actuator 20, any of the individual electrodes 2
4 and the common electrode 25, an active portion of the piezoelectric element in which the piezoelectric sheet 21 is distorted in the stacking direction by piezoelectricity in a portion of the piezoelectric sheet 21 corresponding to the individual electrode 24 to which the voltage is applied. Becomes An active portion of the piezoelectric element in the piezoelectric actuator 20;
And the pressure chambers 16 overlap vertically in plan view of each plate.

The internal volume of the pressure chamber 16 corresponding to each of the individual electrodes 24 is reduced by the distortion of the active portion, so that the ink in the pressure chamber 16 is ejected from the nozzle 54 in the form of droplets. Then, predetermined printing is performed (see FIG. 8).

As described above, by interposing the adhesive layer between the piezoelectric actuator 20 and the cavity plate unit 10 so as to cover all the pressure chambers 16, the adhesive layer does not allow ink to permeate. In addition to acting as a film, the function of firmly fixing the piezoelectric actuator 20 and the cavity plate unit 10 can be simultaneously performed. And since it is an adhesive, the thickness of the layer can be formed extremely thin as compared with the conventional diaphragm plate, and the effect that the inkjet printer head can be manufactured at low cost can be obtained. Further, since the piezoelectric actuators 20 are configured by stacking the piezoelectric sheets 21 and 22 extending over the plurality of pressure chambers 16,
The rigidity of the entire piezoelectric actuator 20 is increased, and it is possible to perform driving at a high frequency without causing vibration unlike a conventional diaphragm plate.

When the active portion of the piezoelectric actuator 20 is selectively driven, the active portion is elastically deformed so as to bend the plane of the plate portion of the piezoelectric actuator 20, so that the active portion is bonded to the piezoelectric actuator. The cavity plate unit 10 also elastically deforms, but in the present invention, the cavity plate unit 10
By providing the concave groove 55 so as to straddle the plurality of pressure chambers 16 in the spacer plate 13 in the above, the thickness of the spacer plate 13 corresponding to the pressure chamber 16 is partially reduced to partially reduce the rigidity. Then, the elastic deformation of the unnecessary (unselected) pressure chamber 16 is reduced, and a so-called cross talk phenomenon, which affects the ink ejection from the pressure chamber 16, occurs. Thus, the effect that the ink droplet to be ejected becomes a droplet can be eliminated.

In the above embodiment, one or a plurality of long concave grooves 55 are formed so as to extend in a direction perpendicular to the direction in which the pressure chambers 16 are arranged (see FIG. 7).
As shown in (1), a recess 56 having a plan view shape substantially the same as the plan view shape of the manifold 12a may be formed on the lower surface side of the spacer plate 13 (the side facing the manifold 12a).

[0036]

As described above, according to the first aspect of the present invention,
The invention described in (1) has a cavity plate unit having a plurality of nozzles and pressure chambers for each of the nozzles arranged in a row in a first direction, and an active portion that can be selectively driven for each of the pressure chambers. In a piezoelectric ink jet printer head having a piezoelectric actuator laminated to discharge ink, the cavity plate unit includes a base plate provided with the pressure chambers, and the pressure chambers after storing ink from an ink supply source. A manifold plate provided with a manifold chamber to be refilled, a spacer plate interposed between the manifold plate and the base plate, and a nozzle plate provided with a nozzle communicating with the pressure chamber, and a laminated structure, The manifold chamber straddles the manifold plate in the direction in which the plurality of pressure chambers are arranged. While it formed so that, in the spacer plate is obtained by forming so as to extend over at least the plurality of pressure chambers opened thin-walled recess in the manifold chamber side.

Although it is possible to reduce the plate thickness of each plate constituting the cavity plate unit as a whole to lower the rigidity of the entire cavity plate unit, it is necessary to secure the capacity of the pressure chamber and the manifold chamber. It is necessary to ensure the thicknesses of the base plate and the manifold plate, and if the thickness of the plates on both sides thereof is too thin, there is a problem that the rigidity of the entire cavity plate unit becomes too low. Therefore, as in the present invention, only the thickness of a part of the spacer plate is reduced, and the spacer facing the manifold chamber is set as a position corresponding to the active portion of the piezoelectric actuator and not affecting the capacity of the pressure chamber. We decided to place a recess on one side of the plate. Since the thin-walled recess is formed so as to straddle the plurality of pressure chambers, the presence of the recess does not obstruct the flow of ink in the manifold chamber, and the active portion is curved. As a result, the rigidity in the direction of elastic deformation can be reduced.

The invention described in claim 2 is the first invention.
In the inkjet printer head according to the above, since the thin-walled recess is formed to have substantially the same size as the manifold chamber, the presence of the recess does not hinder the flow of ink in the manifold chamber. The effect is increased.

According to a third aspect of the present invention, in the ink jet printer head according to the first aspect, the longitudinal direction of the manifold chamber is disposed so as to intersect the arrangement direction of the plurality of pressure chambers, and When the recess is formed in a long groove shape that extends over substantially the entire length of the manifold chamber and straddles the plurality of pressure chambers, the presence of the recess prevents the flow of ink in the manifold chamber. In addition, the effect of reducing the rigidity in the direction in which the active portion is elastically deformed so as to bend can be further improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a piezoelectric inkjet printer head according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing one end of a cavity plate unit and a piezoelectric actuator.

FIG. 3 is an exploded perspective view of a cavity plate unit.

FIG. 4 is a partially enlarged perspective view of a cavity plate unit.

FIG. 5 is an exploded perspective view of the piezoelectric actuator.

FIG. 6 is an enlarged side sectional view of the piezoelectric ink jet printer head taken along line VI-VI of FIG. 1;

FIG. 7 is a plan view showing an arrangement relationship among a concave groove, a manifold chamber, and a pressure chamber in the first embodiment.

FIG. 8 is a partially cutaway perspective view showing an arrangement relationship among a concave groove, a manifold chamber, and a pressure chamber in a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Cavity plate unit 11 Lower layer plate 12 Manifold plate 12a Manifold chamber 13 Spacer plate 14 Base plate 16 Pressure chamber 20 Piezoelectric actuator 21a, 21b, 21c, 21d, 21e, 21f, 2
1g, 22 Piezoelectric sheet 23 Top sheet 24 Individual electrode 25 Common electrode 26 Dummy individual electrode 27 Dummy common electrode 30, 31 Surface electrode 32, 33 Through hole 55 Groove 56 Recess 43 Nozzle plate 54 Nozzle

Claims (3)

[Claims] 1. An ink comprising: a plurality of nozzles; a cavity plate provided with pressure chambers for each of the nozzles in a row in a first direction; and an active portion which can be selectively driven for each of the pressure chambers. A piezoelectric actuator that is formed by stacking a piezoelectric actuator that discharges ink, wherein the cavity plate unit is refilled into each of the pressure chambers after storing ink from an ink supply source and a base plate provided with the pressure chambers. A manifold plate provided with a manifold chamber, a spacer plate interposed between the manifold plate and the base plate, and a nozzle plate provided with a nozzle communicating with the pressure chamber. So as to straddle the manifold chamber in the arrangement direction of the plurality of pressure chambers. While formed, wherein the spacer plate, the ink jet printer head, characterized in that the thin-walled recess is open to the manifold chamber side is formed on at least the plurality of astride the pressure chamber. 2. The ink jet printer head according to claim 1, wherein the thin recess is formed to have substantially the same size as the manifold chamber. 3. A longitudinal direction of the manifold chamber is disposed so as to intersect with a direction in which the plurality of pressure chambers are arranged, and the thin-walled concave portion extends over substantially the entire length of the manifold chamber and the plurality of pressure chambers. The ink-jet printer head according to claim 1, wherein the ink-jet printer head is formed in a long groove shape that straddles.