JP2001179967A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a shearing mode ink jet recording head that the rigidity is low because a partition wall and a top plate forming a pressuring chamber are secured through an adhesive and a specified displacement can not be attained when the barrier is bent. SOLUTION: Between two or more juxtaposed ceramic plates 2, 3, a plurality of piezoelectric ceramic partition walls 4 having a drive electrode 5 are formed while being bonded integrally through sintering at a specified interval. Two ceramic plates 2, 3 disposed vertically and the interposed partition walls 4 define spaces serving as the pressuring chambers 1 of ink in the ink jet recording head 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head mounted on an ink jet recording apparatus for printing characters and images.

[0002]

2. Description of the Related Art In recent years, with the spread of digital processing of information, as a recording apparatus for outputting such information, an ink jet system which is easy to colorize with low running cost has attracted attention.

As an ink jet recording head (hereinafter, referred to as a head) mounted on the ink jet recording apparatus, a fine heater is provided in a pressurized chamber filled with ink, and the ink is heated and boiled by the heater. Then, the ink is pressurized by bubbles generated in the pressurized chamber, and a thermal jet method in which ink droplets are ejected from an ink ejection hole or a wall forming a pressurized chamber filled with ink is bent and displaced by a piezoelectric element, and mechanically. A piezoelectric method has been proposed in which ink in a pressurized chamber is pressurized and ink droplets are ejected from ink ejection holes.

[0004] Among them, the piezoelectric method has the advantages of excellent durability and responsiveness, and the type of ink is not limited because the ink is not directly heated unlike the thermal jet method. However, since it is necessary to mount the piezoelectric element also in the piezoelectric type head, it is difficult to increase the density in terms of structure and process, and today, the partition of the pressurized chamber filled with ink is formed of piezoelectric ceramics, There has been proposed a shear mode type piezoelectric method in which a partition wall between the pressure chambers is deformed by utilizing the shear mode deformation of the piezoelectric ceramic, the ink in the pressure chamber is pressurized, and ink droplets are discharged from ink discharge holes.

As shown in FIG. 6, a conventional shear mode ink jet recording head 50 has a plurality of grooves, one end of which is opened in a piezoceramic plate, and each groove has an ink flow. A flow path member 51 having a passage 53 and a partition wall 52 as a wall partitioning each groove;
The top plate 55 is adhered to the top surface of each partition 52 with an epoxy-based adhesive so as to cover the upper part of the partition wall 52, and the top end of each flow path member 51 is adhered to the open end side of the flow path member 51 with an epoxy-based adhesive. A nozzle plate 57 having an ink discharge hole 56 communicating therewith,
A space formed by the flow path member 51 and the top plate 55 is used as an ink pressurizing chamber 58, and a driving electrode 54 is formed on the upper half of the side surface of each partition 52.

At the rear of the top plate 55, there are provided concave grooves 59 communicating with the respective flow paths 53. Each of the ink tanks (not shown) is connected to each of the ink tanks via a pipe 60 connected so as to communicate with the concave grooves 59. The ink is supplied into the pressurizing chamber 58.

[0007] As shown in FIG. 7, the structure of a head unit having a head 50 is shown.
By applying a command voltage to each of the driving electrodes 54 by the driver IC 18 mounted on the other end of the piezoelectric ceramics, the partition walls 52 whose upper and lower sides are constrained are formed in a substantially "C" shape using the shear mode deformation of the piezoelectric ceramics. Bending displacement, pressurizing chamber 5
Ink 8 is pressurized to discharge ink droplets from the ink discharge holes 56.

Further, as shown in FIG. 8, by fixing the head 50 above and below the fixed substrate 17, the number of ink ejection holes 56 is increased, and the number of ink droplets that can be ejected at one time is increased. In some cases, the printing time was shortened.

In recent years, color printing has been performed using at least four colors of ink such as cyan, magenta, yellow, and black. In such a case, as shown in FIG. The head units shown in FIG. 7 were used at predetermined intervals.

[0010]

However, the conventional ink jet recording head 50 shown in FIG.
Is fixed to the top surface of the partition 52 by bonding, and if the rigidity of the fixing portion is insufficient, the shear mode deformation of the piezoelectric ceramics forming the partition 52 is absorbed, and the partition 52 is bent and displaced by a predetermined displacement amount. In some cases, sufficient pressure cannot be generated in the pressurizing chamber 58 because the pressure cannot be increased. That is, it is difficult to homogenize the bonding conditions between the top plate 55 and all the partition walls 52, and when such bonding conditions vary significantly, a desired ink droplet cannot be discharged from each ink discharge hole 56, and the dot There is a problem that the image quality is deteriorated due to variation in the size or displacement of the landing position of the ink droplet.

The flow path member 51 constituting the head 50
Channel 53 is formed from a piezoelectric ceramic plate by grinding using a diamond blade or the like.
Particles and the like generated at the time of processing are likely to remain in the flow path, and such particles have a problem that the ink discharge holes 56 may be clogged during the driving of the head 50 or may be a source of ink aggregation. Moreover, in the grinding process, chipping or the like is likely to occur in the piezoelectric ceramics forming the partition walls 52, and the yield is not good.

Further, since the interval between the ink ejection holes 56 formed in the head 50 is as narrow as 100 to 2800 μm, when the heads 50 are arranged in two or more rows as in the head unit shown in FIGS. Ink ejection hole 5 of head 50
It is very difficult to align the positions of the dots 6 with each other, and there has been a problem that the dot fixing position is shifted due to the positional shift. For this reason, when a color image is printed by ejecting ink droplets of different colors from the respective heads 50 provided in the head unit shown in FIG. 9, the fixing positions of the dots are shifted for each color due to the positional shift. Has been degraded, and the color image quality has been reduced.

Moreover, in the head unit shown in FIG.
Since a plurality of head units shown in FIG. 7 must be arranged side by side, there is a disadvantage that the interval between the heads 50 cannot be reduced, and the head unit cannot be downsized.

[0014]

In view of the above-mentioned problems, an ink jet recording head according to the present invention has a plurality of partition walls made of piezoelectric ceramics provided with driving electrodes between two or more ceramic plates arranged side by side. And a space formed by the ceramic plates arranged vertically and the partitions between them is used as a pressurizing chamber for the ink.

[0015]

Embodiments of the present invention will be described below.

FIG. 1 is a view showing an ink jet recording head according to the present invention, wherein FIG.
(B) is a sectional view taken along line XX of (a).

The ink jet recording head 10 is provided between two ceramic plates 2 and 3 made of piezoelectric ceramics mainly containing lead zirconate titanate, lead magnesium niobate, lead nickel niobate and the like. 3
Similarly, a plurality of partition walls 4 made of piezoelectric ceramics mainly composed of lead zirconate titanate, lead magnesium niobate, lead nickel niobate, etc. are joined and integrated at predetermined intervals by sintering, and the upper and lower ceramics are formed. The space formed by the plates 2 and 3 and the partition walls 4 therebetween is defined as an ink pressurizing chamber 1.
A flow path member 6, a nozzle plate 8 having an ink discharge hole 7 connected to one of the open ends of the flow path member 6 with an adhesive such as an epoxy resin, and communicating with each of the pressure chambers 1. A closing member 11 having a groove 12 communicating with each pressurizing chamber 1 is joined to the other open end of the path member 6 with an adhesive such as an epoxy resin. A driving electrode 5 is formed.

Further, the closing member 11 has a pipe 16 communicating with the groove 12, and ink is supplied from the ink tank (not shown) to each pressurizing chamber 1 through the pipe 16.

The closing member 11 includes a base 13 having a groove 12 and a lid 14 for closing the groove 12 of the base 13. It is electrically connected to the driving electrode 5 of each partition 4 via an adhesive such as an adhesive. The piezoelectric ceramics forming the partition walls 4 are polarized in the direction of the arrow.

As shown in FIG. 2, the head 10 is fixed to one end of a fixed substrate 17 by bonding, and each driving electrode 5 of the head 10 is fixed by a driver IC 18 mounted on the other end of the fixed substrate 17. And pressurizing the ink in the pressurizing chamber 1 by applying a command voltage to the piezoelectric ceramics so as to bend and displace the partition 4 whose upper and lower sides are constrained in a substantially “U” shape by utilizing the shear mode deformation of the piezoelectric ceramics. Accordingly, ink droplets are ejected from the ink ejection holes 7.

According to the ink jet recording head 10 of the present invention, since the upper and lower parts of the partition wall 4 constituting the pressurizing chamber 1 are joined and integrated with the ceramic plates 2 and 3 by sintering.
It has sufficient rigidity and does not have adhesive variation unlike conventional adhesives. Therefore, since the partition wall 4 can be bent and displaced in accordance with the voltage applied to the driving electrode 5, a desired ink droplet can be stably ejected from each ink ejection hole 7. As a result, there is no variation in dots and no misalignment of the landing positions of ink droplets, so that it is possible to prevent a decrease in image quality.

As will be described later, the head 1 of the present invention
According to No. 0, unlike the conventional head, no grinding is required to form the pressurizing chamber 1, so that no particles or the like remain in the pressurizing chamber 1 and the head 1
Since the ink ejection holes 7 are not clogged or the ink does not coagulate during the driving operation of 0, and the chipping does not occur as in the grinding process, the production yield of the head 10 can be increased.

By the way, in order to manufacture the head unit of FIG. 2 provided with the ink jet recording head 10, as shown in FIG. 3A, lead zirconate titanate, lead magnesium niobate, lead nickel niobate, etc. A plurality of green sheets 40 made of piezoelectric ceramics containing as a main component are prepared. In forming the green sheet 40, a well-known ceramic molding method such as a doctor blade method, a pulling method, an extrusion method, or a roll coater method may be used.

As a first manufacturing method, FIG.
As shown in FIG. 5, an electrode paste 41 such as silver, a silver-palladium alloy, or platinum, which is to be the driving electrode 5, is placed in a predetermined position on the upper and lower surfaces of some of the green sheets 40 in consideration of shrinkage during heat treatment described below. In addition to screen printing, a long hole 43 serving as the pressure chamber 1 is punched out at a predetermined position of another green sheet 40 with a mold. The green sheet 44 forming the long hole 43 may be formed by mixing piezoelectric ceramics with a photosensitive resin or the like. In this case, the long hole 43 is opened by exposure and development using photolithography technology. Alternatively, the openings can be formed by sandblasting or by laser processing.

Next, as shown in FIGS. 3 (c) and 3 (d),
Green sheet 4 to be one of the ceramic plates 3 in the lowermost layer
0, a green sheet 44 having a long hole 43 formed thereon, and a green sheet 4 having an electrode paste 41 printed thereon.
3 are sequentially laminated, a green sheet 40 to be the other ceramic plate 2 is laminated on the uppermost layer, and then thermocompression-bonded. Then, as shown in FIG. (E), a plurality of through holes are juxtaposed,
A molded body 45 in which the electrode paste 41 is printed on the side surface of each through hole along the longitudinal direction is cut out.

Thereafter, the cut molded body 45 is
Degreased at 800C to 800C, then 1000C to 1300C
Baking under a lead atmosphere or an oxygen atmosphere in FIG.
As shown in (f), between the two ceramic plates 2 and 3
A plurality of partition walls 4 provided with drive electrodes 5 along the longitudinal direction are joined and integrated by sintering at predetermined intervals to form a space formed by the two ceramic plates 2 and 3 and each partition wall 4. A flow path member 6 serving as the ink pressurizing chamber 1 is manufactured. The pressure chamber 1 has a height of 150 to 500 μm, a width of 50 to 100 μm,
What is necessary is just to make it about 5-10 mm in length,
It may be formed at a pitch of 100 to 2800 μm.

Then, as shown in FIG. 3 (f), after subjecting the flow path member 6 to polarization processing in the direction of arrow P, FIG.
As shown in FIG. 5, a nozzle plate 8 having an ink discharge hole 7 communicating with each pressurizing chamber 1 is joined to one open end of the flow path member 6 with an adhesive such as an epoxy-based adhesive. At the other open end, a closing member 11 having a concave groove 12 communicating with each pressurizing chamber 1 is joined with an adhesive such as an epoxy-based adhesive, and each driving electrode 5 and the lead wire 15 are electrically connected. The head 10 is formed by electrical connection with an adhesive or the like, and is joined to one end of a fixed substrate 17 on which wiring (not shown) is formed, and a driver IC 18 is mounted on the other end and connected. can do.

As a second manufacturing method, as shown in FIG. 3 (h), a long hole 43 corresponding to the pressurizing chamber 1 is provided between two green sheets 40 corresponding to the ceramic plates 2 and 3. And a green sheet in which an electrode paste 41 such as silver, a silver-palladium alloy, or platinum, which is to be the driving electrode 5, is printed on the side surface of the wall parting the long hole 43 in consideration of shrinkage during heat treatment described later. 46 are stacked in accordance with the height of the partition wall 4, and a laminate is formed by thermocompression bonding. The formation of the elongated hole 43 may be performed by any method of punching with a mold, exposure and development using photolithography, sandblasting, and laser processing, as described with reference to FIG. 3B. Absent.

Next, as shown in FIG. 3 (i), the portion indicated by the dotted line of the laminate is cut, and as shown in FIG. 3 (j),
An electrode paste 4 is placed between the two green sheets 40,40.
1 cuts out a molded body 45 having a plurality of walls printed at predetermined intervals along the longitudinal direction.

Next, the cut compact 45 was heated at 400 ° C.
Degreased at ８００800 ° C., and then baked at 1000 ° C. to 1300 ° C. under a lead atmosphere or an oxygen atmosphere.
As shown in FIG. 2, a plurality of partition walls 4 each having a drive electrode 5 extending in the longitudinal direction are joined and integrated by sintering at predetermined intervals between two ceramic plates 2 and 3, and A flow path member 6 is manufactured in which a space formed by the ceramic plates 2 and 3 and the partition walls 4 is used as a pressure chamber 1 for ink. After a while, FIG.
The head unit can also be manufactured through the polarization treatment of (f) and the assembly process of FIG.

As another means for forming the drive electrode 5, after the polarization process is performed on the flow path member 6 in the stage of FIG. After the resist is unevenly distributed on the lower ceramic plate 3 by heating and the like, the resist is hardened by heating, and then the masking is performed in the pressurizing chamber 1, and then the electroless plating of gold, nickel, or the like is performed. The driving electrode 5 may be formed at a predetermined position in the chamber 1.

Next, another ink jet recording head according to the present invention is shown in FIG. 4, and a head unit provided with the head of FIG. 4 is shown in FIG. 5, respectively.

This ink jet recording head 20 is obtained by stacking four heads 10 shown in FIG. 1 and joining them together by sintering, and mainly comprises lead zirconate titanate, lead magnesium niobate, lead nickel niobate and the like. As in the case of the ceramic plates 21 to 25, lead zirconate titanate is provided between the five ceramic plates 21 to 25 made of piezoelectric ceramics.
A plurality of partition walls 4-1 to 4-1 made of piezoelectric ceramics mainly containing lead magnesium niobate, nickel nickel niobate and the like.
4-4 are bonded and integrated at predetermined intervals by sintering, and two ceramic plates 21 to 2 arranged vertically
5 and a flow path member 26 that defines a space formed by the partition walls 4-1 to 4-4 as pressure chambers 1-1 to 1-4 for ink,
Nozzle plate having ink discharge holes 7-1 to 7-4 joined to one open end of the flow path member 26 with an adhesive such as an epoxy resin and communicating with each of the pressure chambers 1-1 to 1-4. 28, and the other open end of the flow path member 26 is joined with a conductive adhesive,
Grooves 12-1 to 12- communicating with each pressurizing chamber 1-1 to 1-4
The bases 13-1 to 13-4 provided with the base 4 are bonded with an adhesive such as an epoxy-based adhesive, and the lid 1 is placed on the top of the uppermost base 13-1.
4 comprising closing members 11-1 to 11-4,
Driving electrodes 5-1 to 5-4 are respectively formed on the upper halves of the side surfaces of the partition walls 4-1 to 4-4.

The closing members 11-1 to 11-4 include:
As shown in FIG. 5, pipes 16-1 to 16-4 communicating with the grooves 12-1 to 12-4 are connected, and an ink tank (not shown) is connected via pipes 16-1 to 16-4. The ink is supplied to each of the pressurizing chambers 1-1 to 1-4.

Lead lines 15-2 to 15-4 are formed on the lower surfaces of the bases 13-1 to 13-3, and the partition walls 4-2 to 4-4 are driven via a conductive adhesive or the like. Electrodes 5-2 to 5-
4 and a lead 15-1 is also formed on the lower surface of the lid 14, and the partition wall 4 is connected via a conductive adhesive.
-1 drive electrode 5-1. The piezoelectric ceramics forming the partitions 4-1 to 4-4 are polarized in the direction of the arrow.

As shown in FIG. 5, this head 20 is fixed to one end of a fixed substrate 17 by bonding, and is mounted on a plate 19 arranged hierarchically at the other end of the fixed substrate 17. Each driving electrode 5-1
By applying a command voltage to ５−5-4, the partition walls 4-1 to 4-4 whose upper and lower sides are constrained are bent and displaced in a substantially “C” shape using the shear mode deformation of the piezoelectric ceramics. The ink in the pressure chambers 1-1 to 1-4 is pressurized, and ink droplets are ejected from the ink ejection holes 7-1 to 7-4 arranged in rows.

The ink jet recording head 2
0, the upper and lower walls 4-1 to 4-4 of each of the pressurizing chambers 1-1 to 1-4 are joined to the ceramic plates 21 to 25 by sintering so as to have sufficient rigidity. And there is no adhesion variation unlike conventional adhesion. Therefore, according to the voltage applied to the driving electrodes 5-1 to 5-4, the partition walls 4
Since -1 to 4-4 can be bent and displaced, a desired ink droplet can be stably ejected from each of the ink ejection holes 7-1 to 7-4. As a result, there is no variation in dots or displacement of the landing positions of ink droplets.
The image quality can be prevented from lowering.

Further, as in the conventional head, the pressure chamber 1-
Since no grinding is required to form the ink jet holes 1 to 1-4, no particles or the like remain in the pressurizing chambers 1-1 to 1-4. -1 to 7-4 do not cause clogging or aggregation of the ink, and furthermore, there is no occurrence of chipping or the like as in grinding, so that the production yield can be increased.

Further, since the heads 10-1 to 10-4 are joined and integrated by sintering, the heads 10-1 to 10-4 are arranged in a line from the conventional head shown in FIG. Since the distance between the formed ink ejection holes 7-1 to 7-4 can be reduced, the head 20 and the head unit can be downsized, and the ink ejection holes 7- formed in each of the head portions 10-1 to 10-4. 1 to 7-4 can be reduced. Therefore, when printing a color image, the fixing position of dots does not shift for each color, so that intermediate colors can be sufficiently developed, and high-quality color printing can be realized.

The head 1 shown in FIGS.
At 0 and 40, the closing members 11, 11-1 to 11-4
13, 13-1 to 13-4 and lid 14 forming
Can be used as the material for forming the flow path members 6, 26, and it is preferable to use a material having a thermal expansion coefficient similar to that of the piezoelectric ceramics forming the flow path members 6, 26.

The material for forming the nozzle plates 8 and 28 is not particularly limited, and materials such as plastic, metal, ceramics, and glass can be used. For example, polyethylene terephthalate, polyimide,
Polyetherimide, polyether ketone, polyether sulfone, polycarbonate, cellulose acetate, stainless steel, copper chromium molybdenum, aluminum, alumina, zirconia, lead zirconate titanate, and the like can be used, and particularly preferably, it is easy to process. In this respect, polyethylene terephthalate and polyimide resins are preferred.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that improvements and modifications can be made without departing from the scope of the present invention.

[0043]

As described above, in the ink jet recording head of the present invention, a plurality of partition walls made of piezoelectric ceramics having driving electrodes are fired at predetermined intervals between two or more ceramic plates. Forming
By making the space formed by the two ceramic plates arranged vertically and each partition therebetween a pressurizing chamber for ink, the upper and lower sides of the partition forming the pressurizing chamber are firmly joined to the ceramic plate, It has sufficient rigidity and does not have adhesive variation unlike conventional adhesives. As a result, the partition wall can be bent and displaced in accordance with the voltage applied to the driving electrode, so that a desired ink droplet can be stably ejected from each ink ejection hole, and dot dispersion and landing of the ink droplet can be achieved. High-quality printing without displacement can be realized.

Furthermore, unlike the conventional head, the head of the present invention does not require grinding to form the pressurizing chamber, so that no particles or the like remain in the pressurizing chamber, and It does not cause clogging of the ink ejection holes or aggregation of the ink during driving, and furthermore, there is no occurrence of chipping or the like as in grinding, so that the production yield of the head can be increased.

[Brief description of the drawings]

FIGS. 1A and 1B are views showing an inkjet recording head according to the present invention, wherein FIG. 1A is a perspective view with a part thereof cut away, and FIG. 1B is a sectional view taken along line XX of FIG.

FIG. 2 is a perspective view showing a head unit including the inkjet recording head of FIG.

3 (a) to 3 (j) are explanatory views showing steps of manufacturing the ink jet recording head of FIG. 1.

FIG. 4 is a perspective view showing another ink jet recording head according to the present invention.

FIG. 5 is a perspective view showing a head unit including the inkjet recording head of FIG. 4;

FIG. 6 is a partially broken perspective view showing a conventional ink jet recording head.

FIG. 7 is a perspective view showing a head unit on which the inkjet recording head of FIG. 6 is mounted.

FIG. 8 is a perspective view showing another head unit on which the ink jet recording head of FIG. 6 is mounted.

FIG. 9 is a perspective view showing still another head unit on which the ink jet recording head of FIG. 6 is mounted.

[Explanation of symbols]

1: Pressurizing chamber 2, 3: Ceramic plate 4: Partition wall 5: Driving electrode 6: Flow path member 7: Ink ejection hole 8: Nozzle plate 10: Ink jet recording head 11: Closure member 1
2: groove 13: base 14: lid 15: lead wire 17: fixed substrate 18: driver IC

Claims (1)

[Claims] 1. A plurality of partition walls made of piezoelectric ceramics provided with drive electrodes are joined and integrated at predetermined intervals by sintering between two or more ceramic plates arranged in parallel, and are arranged vertically. An ink jet recording head comprising a space formed by the two ceramic plates and each partition between them as a pressure chamber for ink.