JPH08118622A - Printing head for ink jet printer - Google Patents

Abstract

PURPOSE: To enhance the image quality of the image formed on paper by making ejected ink droplets as uniform as possible. CONSTITUTION: A printing head 1 is constituted by bonding a vibration plate 3 composed of a titanium plate to a substrate 2 having recessed parts constituting ink sumps 201, pressure chambers 202, ink passages 204 and ink jet passages 203 formed on the upper and rear surfaces thereof. PZTs are precipitated on the vibration plate 3 at the positions opposed to the pressure chambers 202 and the ink jet passages 203 by a hydrothermal synthesizing method to provide first and second piezoelectric elements 41, 42. Ink is pressurized by the first piezoelectric element 41 to be ejected from each of ink jet orifices 203A and pressurized immediately thereafter by the second piezoelectric element 42 and the ejected ink is instantaneously separated from the ink in each of the ink jet passages 203 to uniformize the size of an ink droplet.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a print head for an ink jet printer using a piezoelectric element as a drive source is known.

FIG. 13 is a cross-sectional view of an essential part showing the structure of a conventional print head of the Kaiser system. The print head 300 shown in the figure has a plurality of dot printing units 305 on the surface.
Are arranged side by side in the paper surface and in the depth direction, and each dot printing unit 305 includes an ink reservoir 301a, a pressure chamber 301b, an ink flow passage 301c, an ink ejection passage 303a, an ink ejection outlet 303b, and a piezoelectric element 304. There is.

Ink pool 301 of each dot printing unit 305
a, the pressurizing chamber 301b, and the ink flow path 301c are configured by forming concave portions of a predetermined pattern on the surface of a substrate 301 made of photosensitive glass, and bonding a vibration plate 302 to the surface of the substrate 301 with an adhesive. There is. Further, the piezoelectric element 304 is
The pressure source of the pressure chamber 302 is a piezoelectric member 30 made of, for example, lead zirconate titanate (hereinafter referred to as PZT).
Electrodes 304a and 304b are formed on the front and back surfaces of 4c. The piezoelectric element 304 is used for the pressure chamber 30 of the vibration plate 302.
It is attached to the position facing 2 with an adhesive.

In addition, the ink ejection passage 303a and the ink ejection port 303b of each dot printing section 305 have a vibration plate 302.
At the tip of the substrate 301 to which the
The nozzle plate 303 on which a and the ink ejection port 303b are formed is bonded by an ultraviolet curable adhesive.

The vibrating plate 302 constitutes a side wall that allows the ceiling portion of the pressurizing chamber 301b to be deformed, and the ink flow passage 301a, the pressurizing chamber 301b and the ink reservoir 30 are provided.
It also constitutes the side wall of 1a.

The print head 300 is manufactured by the following procedure. First, the ink reservoir 301a, the pressure chamber 301b, and the ink flow path 3 are formed on the surface of the substrate 301 made of the photosensitive glass by photolithography.
A concave portion 01c is formed, and a vibration plate 302 made of the same photosensitive glass is bonded to the surface of the substrate 301 by heat fusion.

Next, the substrate 30 to which the diaphragm 302 is joined
1 (hereinafter, this substrate is referred to as a head substrate 306) is used as an electrode (ITO (Indium)
After the Tin Oxide) film 307 is formed, a piezoelectric element 304, which is manufactured in advance as a component, is attached to a position facing the pressure chamber 301b of the vibration plate 302 with an epoxy adhesive. Then, the nozzle plate 303 having the water-repellent ink jet surface is joined to the tip of the head substrate 306 with an ultraviolet curable adhesive to complete the print head 300.

[0009]

By the way, since the characters and images formed on the paper are expressed as a set of printed dots, the dots printed on the paper should be as uniform as possible. desirable. That is, the print head 300
It is desirable that the ink droplets of uniform size be ejected from the ink ejection port 303b of No. 3 at a uniform speed.

In the above conventional print head 300, since the piezoelectric element 304 is attached to the vibration plate 302 with an adhesive, the variation in the adhesive strength between the piezoelectric elements 304 is relatively large. For this reason, the ink pressure is different between the dot printing units 305, and the ink ejection speed varies.

The present invention has been made in view of the above problems, and provides a print head for an ink jet printer capable of forming a high quality image on a sheet by ejecting ink droplets as uniform as possible. To aim.

[0012]

According to the present invention, there is provided a pressurizing chamber having a deformable side wall, a first piezoelectric member provided on an outer surface of the deformable side wall of the pressurizing chamber, and the pressurizing member. An ink ejection path provided on the downstream side of the chamber and having a deformable side wall; and a second piezoelectric member provided on the outer side surface of the deformable side wall of the ink ejection path and near the ink ejection port.
First drive means for applying a drive voltage to the first piezoelectric member to eject ink droplets from the ink ejection port;
Second driving means for applying a driving voltage to the second piezoelectric member at a timing at which the deforming operation of the first piezoelectric member based on the driving voltage ends after the driving voltage is applied to the first piezoelectric member. Is provided (Claim 1).

In the print head for the ink jet printer, the deformable side walls of the pressure chamber and the ink ejection passage are made of a titanium plate, and the first and second piezoelectric members are chemically bonded to the titanium plate. It is preferable that the PZT is composed of the following (claim 2).

[0014]

According to the invention described in claim 1, when a drive voltage is applied to the first piezoelectric member, an electric strain is generated in the first piezoelectric member, and the side wall of the pressurizing chamber is deformed inward. The ink in the pressure chamber is pressurized. The pressurizing force of the ink is transmitted to the ink in the ink ejection path, and the ink is pushed out from the ink ejection port.

Next, the drive voltage is applied to the second piezoelectric member at the timing when the straining operation of the first piezoelectric member ends, that is, the timing when the increased pressure in the pressurizing chamber starts to decrease, and the ink jetting path. The side wall of is deformed inward. As a result, the pressure reducing force in the ink ejection passage increases, and the inner diameter of the ink ejection passage decreases, and the ink pushed out from the ink ejection outlet is instantly separated from the ink in the ink ejection passage to become an ink droplet. To fly.

According to the invention of claim 2, the first
The second piezoelectric member is provided at a position where the piezoelectric member of the titanium plate is formed by chemically bonding PZT to the titanium plate. Since the first and second piezoelectric members are fixed to the titanium plate by chemical bonding, the bonding force is large and uniform. Therefore, the pressure applied to the ink in the pressure chamber is large and stable.

[0017]

1 is a partial plan view of a first embodiment of a print head for an ink jet printer according to the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. 3 is taken along line BB of FIG. Cross section of the main part,
FIG. 4 is an enlarged view of the dot printing unit K of FIG.

The print head 1 shown in FIGS. 1 to 4 constitutes the line head 11 for A4 size standard paper shown in FIG. 7. The line head 11 is formed by stacking 10 print heads 1 in layers. It is designed to be composed. The configuration of the line head 11 will be described later.

The print head 1 includes a substrate 2 made of an insulating material such as silicon or photosensitive glass, a diaphragm 3 made of a titanium plate bonded to the front and back surfaces of the substrate 2, a first piezoelectric element 41 made of PZT, and a first piezoelectric element 41. It is composed of two piezoelectric elements 42 and has 255 dot printing portions 101 on the front and back surfaces respectively.

The print head 1 has a plate shape, and when the arrangement direction of the dot printing portions 101 is the width direction and the direction perpendicular to the arrangement direction is the depth direction, it is approximately 220 mm (width) × 18 mm.
It has a size of (depth) x 12 mm (thickness).

Each dot printing unit 101 has an ink reservoir 20.
1, a pressure chamber 202, an ink ejection path 203, and an ink ejection port 203A. The ink reservoir 201 and the pressure chamber 202 and the pressure chamber 202 and the ink ejection path 203 are connected by an ink flow path 204. . Each dot printing unit 101 has the ink reservoir 201 to the ink flow path 204 on the front and back surfaces of the substrate 2.
Is formed by joining the diaphragm 3 to the front and back surfaces of the substrate 2 with an adhesive. Therefore, the vibrating plate 3 constitutes the ceiling side walls of the ink reservoirs 201 to 204.

The ink reservoir 201 is a portion for supplying ink, and the ink reservoir 201 of each dot printing section 101 is common. The ink reservoir 201 is opened at the base end side surface 2b of the print head 1, and ink is supplied to this opening from an ink source through a pipe. The pressurizing chamber 202 is a pressurizing portion for ejecting ink droplets from the ink ejection port 203A, and the ceiling wall (vibrating plate 3) of the pressurizing chamber 202 is pressed by the inverse piezoelectric effect of the piezoelectric element 4. The ink is pressed by deforming it to the side.
Since the ink ejection ports 203A are arranged at high density,
The pressure chambers 202 of the adjacent dot printing units 101 are formed at positions displaced from each other in the front-rear direction (see FIG. 1).

The ink ejection passage 203 is a portion for adjusting the size of the ink droplet ejected from the ink ejection port 203A. The pressure chamber 202, the ink flow path 204, and the ink ejection passage 203 have a rectangular cross section, and the cross-sectional area of the ink outflow passage is gradually reduced from the pressure chamber 202 to the ink ejection port 203A. ing. In this embodiment, the cross-sectional areas S1, S2, S3 of the pressurizing chamber 202, the ink flow path 204, and the ink ejection path 203 are, for example, S1 = 0.15 m.
m ² , S2 = 0.03 mm ² , and S3 = 0.0025 mm ² . In order to allow the ink to flow out smoothly, the boundary between the pressure chamber 202 and the ink flow path 204, the boundary between the ink flow path 204 and the ink ejection path 203, etc. is tapered so that the cross-sectional area does not change suddenly. (See Figure 1).

The substrate 2 has a predetermined pattern on its front and back surfaces, which corresponds to the ink reservoir 201, the pressurizing chamber 202, the ink ejection passage 203, and the ink flow passage 204 of each dot printing portion 101 by using the photolithography technique. A recess is formed.

The vibrating plate 3 is joined to the substrate 2 with an adhesive and constitutes part of side walls of the ink reservoir 201, the pressurizing chamber 202 and the like of each dot printing portion 101 formed on the surface thereof. Further, the vibration plate 3 constitutes a deformable side wall of each pressurizing chamber 202, and the first and second piezoelectric elements 41,
It also constitutes 42 common electrodes.

The first piezoelectric element (first piezoelectric member) 41
Is a pressure source for pushing out the ink from the ink ejection port 203A, and is approximately 1 mm (width) × 4 mm (length) × 0.02 mm
It is made of a strip-shaped PZT having a size of (thickness), and is provided in a state of being chemically bonded to a position corresponding to each pressurizing chamber 202 on the outer surface of the diaphragm 3.

The second piezoelectric element (second piezoelectric member) 42 instantly separates the ink ejected from the ink ejection port 203A from the ink ejection port 203A to generate uniform ink droplets. Pressure source of about 0.2 mm
It has a rectangular parallelepiped shape having a size of (width) × 0.5 mm (length) × 0.02 mm (thickness) and is chemically bonded to the outer surface of the vibration plate 3 at a position corresponding to each ink ejection passage 203. It is provided.

FIG. 5 is a diagram showing a method of manufacturing the print head. For convenience of drawing, the portion of the second piezoelectric element 42 is omitted. First, it is assumed that the substrate 2 is prepared in advance by the above method. Next, the piezoelectric elements 41 and 42 are formed at predetermined positions on the vibration plate (titanium plate) 3 by the following procedure.

That is, the photosensitive resist 5 is applied to the surface of the titanium plate 3 (FIG. 5A), and the photosensitive resist 5 at the positions where the first and second piezoelectric elements 41 and 42 are to be formed is photoetched. Are removed by (step (b)). After that, the photosensitive resist 5 on the titanium plate 3 is hydrothermally synthesized.
PZT is deposited at the position where the is removed to form the first and second piezoelectric elements 41 and 42 (FIG. 7C).

FIG. 6 shows that PZ is applied to a titanium plate by the hydrothermal synthesis method.
It is a figure which shows the method of depositing T. P to titanium plate 3
The precipitation of ZT consists of a first step of forming a PZT crystal nucleus at a predetermined position of the titanium plate 3 and a second step of growing a PZT crystal in the crystal nucleus. Further, the thickness of PZT is controlled to a desired thickness by repeating the second step a plurality of times.

The first step is the molar ratio Pb of Pb and Zr, Pb.
Lead nitrate (Pb (NO ₃ ) ₂ ) so that / Zr becomes approximately 2.29,
An aqueous solution 8 in which zirconium oxychloride (ZrOCl ₂ · 8H ₂ O) and potassium hydroxide (KOH (8N)) were mixed at a predetermined ratio and a titanium plate 3 were placed in an autoclave 7, and the autoclave 7 was further filled with silicon oil 9 It is carried out by placing it in a bath in a constant temperature bath 10 filled with and heating it according to a predetermined temperature profile (for example, 150 ° C. + 48 hours).

In the second step, lead nitrate, zirconium oxychloride, titanium tetrachloride (TiCl ₄ ) and titanium tetrachloride (TiCl ₄ ) are added so that the molar ratio of Pb, Zr and Ti is Pb: Zr: Ti = 110: 52: 48. Aqueous solution 8 in which potassium hydroxide (KOH (4N)) is mixed in a predetermined ratio and titanium plate 3 which has undergone the first step
And are put in the autoclave 7, and then the autoclave 7 is put in a bathroom in a thermostatic chamber 10 filled with silicon oil 9 to have a predetermined temperature profile (for example, 120 ° C. +
Heating for 24 hours).

When a PZT crystal is formed at a predetermined position on the titanium plate 3 by the hydrothermal synthesis method, the titanium plate 3 is washed with distilled water to complete the PZT forming step (FIG. 5).
(C)).

Subsequently, a nickel (Ni) electrode 6 is formed on the upper surface of each piezoelectric element 4 of the titanium plate 3 on which the piezoelectric element 4 is formed, and the process of forming the piezoelectric element 4 on the vibration plate 3 is completed (FIG. 5 (d)). Then, the vibration plate 3 on which the piezoelectric element 4 is formed is bonded to predetermined positions on the front and back surfaces of the substrate 2 with an epoxy adhesive to complete the print head 1 (FIG. 5).
(E)).

As described above, since the PZT is deposited at a predetermined position on the vibration plate 3 by the hydrothermal synthesis method to form the first and second piezoelectric elements 41 and 42, the piezoelectric force applied to the vibration plate 3 is reduced. The accuracy of the formation positions of the elements 41 and 42 is improved. Further, since the first and second piezoelectric elements 41 and 42 are bonded to the vibration plate 3 by chemical bonding, the bonding force is strong and the mounting strength variation between the elements is reduced. This improves the driving efficiency and stability of the pressure source of each dot printing unit 101.

Further, the vibrating plate 3 directly constitutes a part of the side wall of the pressurizing chamber 202 and the ink ejection passage 203, and
Since it is a common electrode for the first and second piezoelectric elements 41, 42, the structure of the print head 1 is simplified, the work of assembling the print head 1 is simplified, and the work efficiency is also improved.

FIG. 7 is a perspective view of a line head constructed by combining print heads in multiple stages.

The line head 11 has a head portion 111 formed by stacking ten print heads 1 in the height direction via electrode substrates 12 and 12 '(see FIG. 8). The side is supported by the support portion 112. With this configuration, the tip surface 11a of the line head 11 is
5100 ink ejection ports 203A have 20 rows x 255
They are arranged in a matrix of columns.

It should be noted that the ink ejection ports 203A of even rows (the ink ejection ports 203 formed on the back surface side of each print head 1)
A is an odd-numbered row of ink ejection ports 203A (each print head 1).
The position is displaced by 1/2 pitch in the arrangement direction with respect to the ink ejection port 203A) formed on the front surface side. Also,
The upper and lower print heads 1 have a pitch (0.
They are arranged so that their positions are shifted by 0425 μm).

The supporting portion 112 is the electrode substrate 12, 1 described above.
It is a connecting portion for connecting the control lines of the first and second piezoelectric elements 41 and 42 provided on the 2'to a drive control circuit (not shown), and also connects the print head 1 of each print head 1 from an ink supply portion (not shown). It is an ink replenishing section for replenishing the ink in the ink reservoir 201.

FIG. 8 is a sectional view of the main part of the head part 111. The head portion 111 is configured by stacking the ten print heads 1 in the height direction via the electrode substrates 12 and 12 'as described above. The electrode substrate 12 interposed between the print heads 1 is configured by adhering the FPC 122 having the control line and the connection electrode 13 formed on both surfaces of the insulating support 121, and the print heads 1 of the uppermost and lowermost layers are bonded together. The electrode substrate 12 'attached to the outer surface is an insulating support 1
The FPC 122 having the control line and the connection electrode 13 formed thereon is bonded to one surface of the FPC 21.

The support 121 of the electrode substrate 12 has a thickness of approximately 1 mm, and as described above, the ink ejection port 203.
The line pitch of A is set to be about 1 mm.

The electrode substrates 12 and 12 ′ have the same shape as that of the print head 1 in plan view, and are attached to the upper and lower surfaces of each print head 1 in pressure contact with each other. At this time, the connection electrodes 13 formed on the FPC 122 of the electrode substrates 12 and 12 '.
Is pressed against the electrode 6 formed on the upper surface of the corresponding first piezoelectric element 41 or second piezoelectric element 42, so that each piezoelectric element 41, 42 is connected to the control line via the connection electrode 13. Has become. The first and second piezoelectric elements 41 and 42 are connected to the drive control circuit via the control line of the FPC 122, the diaphragm 3 (common electrode), and the support 112.

Next, regarding the printing operation of the print dot portion,
This will be described with reference to FIGS. 9 and 10. FIG. 9 is a diagram showing the application timing of the drive voltage of the second piezoelectric element. Also,
FIG. 10 is a diagram for explaining the ink droplet ejection operation,
(A) to (e) are periods (a) to (e) of FIG. 9, respectively.
FIG. 3 is a cross-sectional view of the main parts showing the state of the print head in FIG.
The dot printing unit 101 temporarily returns the diaphragm 3 from the state in which it is deformed inside the pressure chamber 202 to the original state, and again deforms it inside the pressure chamber 202 to eject ink droplets from the ink ejection port 203A. It is controlled to eject.

Therefore, when the ink droplets are not ejected from the dot printing unit 101, the drive voltage V1 of a predetermined level is constantly applied to the first piezoelectric element 41 (period (a) in FIG. 9), and the dot printing unit 101 concerned. The diaphragm 3 is held inside the pressurizing chamber 202 in a deformed state (see FIG. 1).
0 (a)).

When ejecting ink droplets from the dot printing section 101, the level of the drive voltage V1 is gradually lowered from the timing t1 (period (b) in FIG. 9), and the deformed diaphragm 3 is gradually restored to its original state. It is returned to the state. In the period (b), as shown in FIG. 10 (b), the contracted first piezoelectric element 41 expands in the longitudinal direction (S1 direction), and the diaphragm 3 bent toward the pressurizing chamber 202 gradually moves. Restore upward (S2 direction).

Then, at the timing t2 when the drive voltage V1 reaches the reference low level and the diaphragm 3 completely returns to the original state, the first piezoelectric element 41 is again pressed to pressurize the ink.
A drive voltage V1 of a predetermined level is applied. Timing t
When the driving voltage V1 of a predetermined level is applied to the first piezoelectric element 41 in 2, the electrostriction in the contraction direction (S3 direction in FIG. 10C) is generated in the first piezoelectric element 41 due to the inverse piezoelectric effect. As a result, the portion of the vibrating plate 3 where the first piezoelectric element 41 is formed instantly bends toward the pressurizing chamber 202 (FIG. 10C, bending in the S4 direction). Due to the bending of the vibrating plate 3, the ink ejection path 2
The ink in 03 is pressurized toward the ink ejection port 203A side (pressing in S5 direction in FIG. 10C), and the ink ejection passage 20
The ink R in 3 is ejected from the ink ejection port 203A.

On the other hand, in the second piezoelectric element 42, the electrostriction of the first piezoelectric element 41 ends, and the ink R is ejected to the ink ejection port 20.
At timing t3 when the drive voltage V2 is pushed out from 3A, a pulsed drive voltage V2 of a predetermined level is applied (FIG. 9). When the drive voltage V2 of a predetermined level is applied to the second piezoelectric element 42, an electrostriction occurs in the second piezoelectric element 42 in the contraction direction (direction S6 in FIG. 10D) due to the inverse piezoelectric effect, which causes vibration. The portion of the plate 3 on which the second piezoelectric element 42 is formed bends toward the ink ejection passage 203 side (deflection in S7 direction in FIG. 10D). Due to the bending of the vibrating plate 3, the ink in the vicinity of the ink ejection port 203A in the ink ejection passage 203 is discharged into the ink ejection port 2
The ink is pressurized to the 03A side (FIG. 10D, S8 direction pressure), and the other inks are pressurized to the pressure chamber 202 side (FIG. 10D, S9 direction pressure).

Therefore, the ink R pressed by the electrostriction generated in the first piezoelectric element 41 and pushed out from the ink ejection port 203A is further pressed by the electrostriction generated in the second piezoelectric element 42, resulting in higher speed. Is ejected from the ink ejection port 203A.

Drive voltage V applied to the second piezoelectric element 42
2 decreases to the reference low level at the timing t4 after a lapse of a predetermined time from the timing t3 (FIG. 9k period (d)). As a result, a stress (a stress in the direction S10 in FIG. 10E) that extends in the longitudinal direction is generated in the second piezoelectric element 42, and the vibration plate 3 is directed to the outside of the ink ejection path 203 (FIG. 10E). , S11 direction) and the bending is eliminated.

The ink ejection path 2 is formed by the above-described bending elimination operation.
03 is decompressed, and the ink R in the vicinity of the ink ejection port 203A in the ink ejection passage 203 is discharged to the pressure chamber 202 side (see FIG.
(E), the ink R pushed back from the ink ejection port 203A in the S12 direction) is instantaneously separated from the ink in the ink ejection passage 203 at timing t4, and is ejected as an ink droplet due to surface tension. To be done.

As described above, the second piezoelectric element 42 is provided in the vicinity of the ink ejection port 203 on the side wall (vibrating plate 3) forming the ink ejection channel 203, and the ink ejection port 203A is pressurized by the first piezoelectric element 41. Ink R extruded from
Is further pressed by the second piezoelectric element 42, the ink R is ejected from the ink ejection port 203A at a higher speed than when the ink R is pressed by only the first piezoelectric element 41,
It is possible to reduce variations in the ejection position of ink droplets on the paper. Further, if the flying speed of the ink droplets becomes high, the distance between the print head 1 and the paper can be lengthened, so that the degree of freedom in designing increases, which is advantageous in the application to an inkjet printer.

Further, while the collision force of the ink droplet with respect to the paper is increased, the ink R pushed out from the ink ejection port 203A is instantly separated from the ink R in the ink ejection passage 203 and has a uniform size. Therefore, it is possible to improve the image quality of the image formed on the sheet (the image formed by dot printing).

In particular, since the second piezoelectric element 42 is caused to instantaneously generate electric strain to generate a pressurized state and a depressurized state in the ink ejection passage 203, the ink ejection port 2
The ink R extruded from 03A and the ink remaining in the ink ejection passage can be separated instantaneously.

Further, the first and second piezoelectric elements 41, 42
Is formed by precipitating PZT on the titanium plate 3, so that the coupling force with the vibration plate 3 is high and stable, so that the variation in the pressure applied by the first and second piezoelectric elements 41, 42 is reduced. In addition, the uniformity of the ink droplets can be improved.

FIG. 11 is a sectional view of the main part of the second embodiment of the print head, which is equivalent to FIG. 4 of the first embodiment.

The second embodiment is a vibrating plate 3 made of a titanium plate.
Instead of this, a vibration plate 31 made of a substrate 14 made of a glass substrate and a titanium thin film 15 formed on this surface by sputtering or vapor deposition is used. In the print head 1 ', PZT is formed on the titanium thin film 15 of the vibration plate 31 at the position where the first and second piezoelectric elements 41 and 42 are to be formed by the same method as in the first embodiment, and the PZT is formed. The vibrating plate 31 thus formed is bonded to the surface of the substrate 2 with an adhesive to be manufactured.

FIG. 12 is a sectional view of the principal part of the third embodiment of the print head, which is equivalent to FIG. 4 of the first embodiment.

The third embodiment is a modification of the diaphragm 31 of the print head 1'according to the second embodiment. That is,
The vibrating plate 31 has the titanium thin film 15 formed on the entire front and back surfaces of the glass substrate 14, and the titanium thin film 15 is used as the common electrode of the piezoelectric elements (PZT) 41 and 42. The 1 ″ diaphragm 32 has an ITO thin film 16 formed as a common electrode on the entire surface of the glass substrate 14, and the first and second piezoelectric elements 4 on the ITO thin film 16 are formed.
The titanium thin film 15 is formed at the positions where 1, 42 should be formed.

Also in the print head 1 ", PZT is formed on the titanium thin film 15 of the vibration plate 32 by the same method as in the first embodiment, and the vibration plate 32 having the PZT formed thereon is attached to the front and back surfaces of the substrate 2 with an adhesive. Manufactured by joining.

Similar to the first embodiment, the second and third embodiments also have the effect of improving the accuracy of the formation positions of the first and second piezoelectric elements 41 and 42. Further, since the attachment strength of the piezoelectric element 4 to the vibrating plates 31 and 32 is high and the variation in the attachment strength between the elements is small, the drive efficiency and stability of the pressure source of each dot printing unit 101 are improved. be able to. Further, the diaphragms 31 and 32 are attached to the glass substrate 14
Therefore, the residual vibration when the piezoelectric element 4 is driven is rapidly attenuated, and the breakage of ink droplets ejected from the ink ejection port 203A is also improved.

By the way, in the above-mentioned embodiment, the common electrode of each piezoelectric element 41, 42 is provided on the side of the vibration plate to be joined to the side of the substrate 2, but the individual electrode of each piezoelectric element 41, 42 is provided on the side of the vibration plate. May be. In this case, each piezoelectric element 41, 42
The electrode 6 on the upper surface of the
The connection electrode 13 formed on the 12 'FPC 122 serves as a common electrode, and the electrodes 6 on the upper surfaces of the piezoelectric elements 41 and 42 are connected via the connection electrode 13. The one in which the individual electrodes of the first and second piezoelectric elements 41 and 42 are provided on the diaphragm side are
Since the electrode substrates 12 and 12 'can be pressed against the print head 1 without considering the positional accuracy, there is an advantage that the line head 11 can be easily assembled.

[0063]

As described above, according to the first aspect of the invention, the first piezoelectric member, which is the first pressure source, is provided on the side wall of the pressurizing chamber, and the ink on the side wall of the ink ejection passage is formed. A second piezoelectric member, which is a second pressure source, is provided in the vicinity of the ejection port, pressure is applied to the ink by the first piezoelectric member, and the ink is ejected from the ink ejection port. Since the generated ink is pressurized by the second piezoelectric member, the ink ejected from the ink ejection port is instantly separated from the ink in the ink ejection path to form an ink droplet, and the size of the ink droplet is uniform. Becomes possible.

Further, since the flying speed of ink droplets can be made higher than that in the case where pressure is applied only by the first piezoelectric element, the variation in the ejection position of ink droplets on the paper is reduced, and the image formed on the paper ( The image quality of an image formed by dot printing) can be improved. Further, the distance between the print head and the paper can be increased, which increases the degree of freedom in design.

According to the second aspect of the invention, since the first and second piezoelectric elements are formed of PZT chemically bonded to the vibration plate made of titanium, the first and second piezoelectric elements are vibrated. It has a high bonding force with the plate and is stable. As a result, variations in the pressure applied by the first and second piezoelectric elements can be reduced, and the size of ink droplets can be made more uniform.

Further, since the piezoelectric member is provided by depositing PZT on the titanium plate, the conventional bonding step is not required and the manufacturing becomes easy.

[Brief description of drawings]

FIG. 1 is a partial plan view of a first embodiment of a print head for an inkjet printer according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

3 is a cross-sectional view of the main part of BB of FIG.

FIG. 4 is an enlarged view of a pressure unit K of FIG.

FIG. 5 is a diagram showing a method of manufacturing a print head according to the present invention.

FIG. 6 is a diagram showing a method of depositing PZT on a titanium plate by a hydrothermal synthesis method.

FIG. 7 is a perspective view of a line head.

FIG. 8 is a cross-sectional view of a main part of a head part.

FIG. 9 is a diagram showing an application timing of a drive voltage applied to a second piezoelectric element.

FIG. 10 is a diagram for explaining an ink droplet ejection operation,
(A) to (e) are periods (a) to (e) of FIG. 9, respectively.
FIG. 3 is a cross-sectional view of the main parts showing the state of the print head in FIG.

FIG. 11 is a cross-sectional view of essential parts of a second embodiment of the print head.

FIG. 12 is a cross-sectional view of essential parts of a third embodiment of the print head.

FIG. 13 is a cross-sectional view of essential parts showing the structure of a conventional print head of the Kaiser method.

[Explanation of symbols]

 1, 1 ′, 1 ″ Print head 101 Dot printing unit 2, 2 ′ Substrate 201 Ink reservoir 202 Pressurizing chamber 203 Ink ejection passage 203A Ink ejection outlet 204 Ink passage 3, 31, 32 Vibration plate 41 First piezoelectric element 42 Second piezoelectric element 5 Photosensitive resist 6 Electrode 7 Autoclave 8 Aqueous solution 9 Silicon oil 10 Constant temperature bath 11 Line head 111 Head part 12, 12 'Electrode substrate 121 Support 122 FPC 13 Connection electrode 14 Glass substrate 15 Titanium thin film 16 ITO thin film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Watanabe 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Industrial Co., Ltd. (72) Setsuo Hori 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Within Kogyo Co., Ltd.

Claims (2)

[Claims] 1. A pressurizing chamber having a deformable side wall, a first piezoelectric member provided on an outer surface of the deformable side wall of the pressurizing chamber, and a downstream side of the pressurizing chamber, An ink ejection path having a deformable side wall, a second piezoelectric member provided on the outer surface of the deformable side wall of the ink ejection path in the vicinity of the ink ejection port, and an ink droplet from the ink ejection port. First driving means for applying a drive voltage to the first piezoelectric member to eject it, and a deforming operation that occurs in the first piezoelectric member based on the drive voltage after the drive voltage is applied to the first piezoelectric member. And a second driving unit that applies a driving voltage to the second piezoelectric member at the timing when the printing head is finished. 2. The print head for an ink jet printer according to claim 1, wherein the deformable side wall of the pressure chamber and the ink ejection path is made of a titanium plate, and the first and second piezoelectric members are made of the titanium plate. A print head for an ink jet printer, which is PZT chemically bonded.